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SOUTHERN AFRICA

INTRODUCTION

In southern Africa, 10 countries or politicaljurisdictions lie south of Zaire and the UnitedRepublic of Tanzania, occupying an area of 6million square kilometres (Fig . 20.1). Thisland mass consists principally of a greatcentral plateau, primarily temperate to sub-tropical in climate ; in 1970 its estimatedpopulation amounted to 54 million . The vastdeserts of the Namib and Kalahari in the westencompass much of Namibia and Botswana,giving way to undulating plains and savannato the east and eventually to detached groupsof hills and mountains which extend fromMalawi through western Mozambique andeastern Zimbabwe (called Southern Rhodesiaprior to 1980).

In 1967, when the Intensified SmallpoxEradication Programme began, smallpoxthroughout southern Africa did not appear tobe a major problem. Four areas-Angola,Botswana, Lesotho and Namibia-were be-lieved to be non-endemic ; 6 other areasrecorded a total of only 534 cases in 1966 and262 in 1967. Health services in most parts ofsouthern Africa were generally more exten-sive than elsewhere in the continent and all

CHAPTER 20

Contents

969

had some type of organized programme ofsmallpox vaccination. Although smallpox wasundoubtedly a greater problem than officialdata conveyed, it was thought to be not aswidespread or of such high incidence as inneighbouring Zaire or the United Republic ofTanzania, for example .

Given the status of smallpox and thenational resources available in many of thecountries, prospects for the early interruptionof smallpox transmission throughout this vastarea might have appeared hopeful . However,political problems made it difficult for WHOto cooperate with the authorities in largeparts of southern Africa, and these constraintsinhibited the programme. Only 4 countries,with a total population of 10 .4 million (in1970), were Member States of WHO with fullvoting rights (Table 20.1) . A fifth, Swaziland,became independent in 1968 and joinedWHO a few years later. Official contactbetween the Organization and the healthauthorities of the other 5 political jurisdic-tions, which had a total population (in 1970)of 42.8 million, was difficult at best and incertain cases practically nonexistent . Angolaand Mozambique, both Overseas Provinces ofPortugal until 1975, were preoccupied with a

PageIntroduction 969Zambia 972Malawi, Mozambique and Southern Rhodesia 975

Background 975Vaccination campaigns 976The smallpox situation 977Age distribution of cases 981

South Africa,Swaziland

Botswana, Lesotho, Namibia and981

Background 981Lesotho, Namibia and Swaziland 982South Africa 983Botswana 988

Angola 995Conclusion 995

970

0 No endemic smallpox in 1967

® Not independent or not in effective relations with WHO

Fig . 20 .1 . Southern Africa : countries and territories,smallpox endemicity, and relationship with WHO,1967. The endemicity shown reflects the situation in1967 as determined later .

protracted and costly civil war. Contact withtheir health authorities had to be madethrough the government in Lisbon, for whichsmallpox eradication was an issue of littlesignificance compared with other problems .Namibia (South West Africa) was adminis-tered by South Africa, which, though still aWHO Member State, had been deprived ofvoting privileges and services by the Seven-teenth World Health Assembly in 1964 andwhich had subsequently ceased to pay itsannual contribution or to attend the WorldHealth Assembly . Communications betweenWHO and South Africa all but ceased at thistime, along with South Africa's participationin the Organization's activities . Until 1965,Southern Rhodesia had been an AssociateMember of WHO, being represented by theUnited Kingdom in its international rela-tions. When the government unilaterallydeclared independence, its rights were sus-pended on the initiative of the United King-dom. Communications between WHO andSouthern Rhodesia had officially to be con-ducted through the government in London,but there was little or no official contactbetween the United Kingdom and the newgovernment of Southern Rhodesia.

The only permissible contact betweenWHO and the 5 above-mentioned political

SMALLPOX AND ITS ERADICATION

jurisdictions was embodied in the provisionsof the International Health Regulations,which required each to report weekly toWHO Headquarters the number of cases ofsmallpox, as well as other stipulated"quarantinable diseases", and the areas thatwere affected . WHO Headquarters, in turn,could query reports and transmit informationdeemed to be of importance in the control ofthese diseases. Although many of the authori-ties concerned, like those of some othercountries, were neither prompt nor com-prehensive in their reporting, this contact,tenuous as it was, proved to be an importantone.

A further difficulty lay in the fact thatsmallpox eradication held little interest forSouth Africa, in which an especially mildform of variola minor was prevalent, theseverity of which was comparable to that ofchickenpox.

In the circumstances, WHO could freelycommunicate with and provide assistanceonly to its "active" Member States, whichtogether accounted for just 20% of thepopulation of southern Africa. It was hopedthat in the other endemic areas, programmeswould eventually be conducted, if for noother reason than to avoid opprobrium in theeyes of independent African governmentswhich had succeeded in eradicating smallpox .

It was therefore difficult to assess the extentof endemic smallpox in most countries ofsouthern Africa between 1967 and 1971, notonly because of problems of communication

Table 20 . I . Status of political jurisdictions insouthern Africa, 1967-1975

a Deprived of voting privileges and services In 1964 .

Population in 1970(thousands)

Area(km2)

WHO Member States:Botswana 623 600 372Lesotho 1 064 30 355Malawi 4 518 1 18 484South Africaa 22 760 1 221 037Swaziland 426 17 363Zambia 4 189 752 614

Political jurisdictionsadministered by othercountries:

Angola 5 588 1 246 700Mozambique 8 140 799 380Namibia 1 042 824 292

WHO membership insuspense:Southern Rhodesia 5 308 390 580

but also because the completeness of notifica-tion improved only slowly during this period .Few outbreaks in any country were inves-tigated by appropriately trained staff or wereconfirmed by laboratory diagnosis . As a con-sequence, the extent of underreporting, thenumbers of reported cases and outbreaks thatrepresented importations from other coun-tries, and the numbers of cases of chickenpoxthat might have been misdiagnosed assmallpox were, and remain, a matter ofconjecture .

Mass vaccination campaigns, assisted byWHO, were conducted in Botswana, Malawiand Zambia ; similar campaigns, assisted byWHO and UNICEF, were carried out inLesotho and Swaziland . None, except theBotswana campaign, was particularly wellexecuted . Nevertheless, transmission was in-terrupted in Zambia in 1968 and in Swazilandin 1966 or 1969, as is discussed later in thischapter . In Malawi, the disease disappeared in1971 . Lesotho's last cases had occurred in1962, 5 years before the beginning of theIntensified Programme .

Of the 5 political jurisdictions in southernAfrica referred to earlier, Angola andNamibia remained smallpox-free, but en-demic smallpox was present in 1967 in theother 3-Mozambique, South Africa andSouthern Rhodesia . Because of political con-straints, they received no help from WHO intheir programmes. Mozambique conductedan extensive vaccination campaign in areasaccessible to the health authorities, and inFebruary 1969 the last cases were detected .Southern Rhodesia recorded small numbers ofcases throughout 1970, all of them along itseastern border with Mozambique. The lastknown case occurred in December 1970, butwhether it was the last in a continuing chainof endemic transmission or a result of im-portations from remote areas of Mozambiqueor Malawi remains unknown . South Africabegan active eradication measures in 1970,conducting extensive systematic vaccinationcampaigns in northern parts of TransvaalProvince, its only known endemic area . In1971, it recorded its last indigenous case .

From February to August 1971, no cases ofsmallpox were reported to WHO from anycountry in southern Africa. Just when hopewas growing that smallpox had beeneliminated from this large area, cases began tobe reported from Botswana, a hithertosmallpox-free country, adjacent to SouthAfrica's Transvaal Province . During the

20. SOUTHERN AFRICA

tw

Endemic areas in 1967

971

Fig . 20.2 . Southern Africa : probable extent ofendemic smallpox, 1967 .

preceding 6 years, only a single imported casehad been detected in Botswana. Vaccinialimmunity throughout the country was lowand smallpox began to spread . This wasalarming. Not only might smallpox againbecome established in a country that had beenfree from it, but it was feared that it mightspread through the populated areas in north-western Botswana into areas of Angola whichwere inaccessible because of civil war . Ifsmallpox were to become re-established there,the prospects for eradication would besignificantly diminished . Effective measuresto control the disease were greatly delayedbut, by good fortune, it remained confined toBotswana, in which more than 1000 caseswere recorded during 1972 and transmissionpersisted until November 1973 .

On the basis of a retrospective review ofdata collected during the course of theprogramme and, subsequently, duringactivities leading to certification, it is prob-able that in 1967 there were not more than 5comparatively small foci of smallpox (Fig.20 .2). One was in Zambia in areas adjacent tothe then heavily endemic Katanga (Shaba)Province of Zaire . A second straddled theMozambique-United Republic of Tanzaniaborder, where a Mozambican independencemovement was centred and where militaryforces associated with this movement, as wellas refugees, moved into and out of the UnitedRepublic of Tanzania. A third lay in central

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Mozambique and southern Malawi, likewisean area in which security was a problem ; afourth was in rural mountainous areas ofSouthern Rhodesia and may or may not haveextended into adjacent areas of Mozambique ;the fifth was in Transvaal Province of SouthAfrica. In all areas except South Africa,smallpox with a case-fatality rate of 5-15prevailed ; in South Africa, a very mild formof variola minor was present with a case-fatality rate of less than 1% .

In this sparsely populated region of Africa,smallpox was readily interrupted withnational or regional mass vaccination cam-paigns, few of which are believed to haveachieved the high levels of vaccinial immun-ity attained in Zaire and western Africa.Moreover, except in Botswana, programmesof surveillance and containment were neverwell developed . However, the eradicationprogramme served in some countries todevelop reporting systems and to promoteroutine vaccination against this and otherdiseases in existing health facilities . It isapparent in retrospect, though, that eradica-tion might have been achieved more readilyand more rapidly if freeze-dried vaccine hadbeen supplied to existing health programmesand if simple surveillance activities had beendeveloped .

This chapter discusses first the activities inZambia and then the programmes in Malawi,Mozambique and Southern Rhodesia. A thirdsection deals with smallpox in the adjacent

Table 20 .2. Zambia : number of reported cases ofand deaths from smallpox and case-fatality rates, 1956-1973, and numberof vaccinations performed, 1964-1973

x0

aN

0Nd

Uuvdt!0avoC

a . = data not recorded.b Imported from Zaire.

countries of South Africa, Botswana, Lesotho,Namibia and Swaziland. Lastly, activities insmallpox-free Angola are briefly described .

ZAMBIA

Zambia, a subtropical country consistinglargely of wooded plateau, became indepen-dent in 1964. Its population of 3.8 million (in1967) lived primarily in scattered villages,only 700 000 being resident in the 9 majortowns. Its road system was comparativelyextensive, as was its network of healthfacilities, which included 60 hospitals, 93urban and specialized clinics and 323 ruralclinics. Many of these were staffed by expa-triates, there being at that time only 3Zambian physicians and a dearth of Zambianparamedical staff. Few of these health units,however, provided vaccination againstsmallpox.

Smallpox, with a case-fatality rate of 5-15%, similar to the form existing inneighbouring Zaire, had been prevalent formany years (Table 20 .2) . Mass vaccinationcampaigns employing liquid vaccine wereconducted during periodic outbreaks .

In 1963-1964, major epidemics began tooccur in Zambia (Fig . 20.3), primarily alongthe Zairian border. The new governmentresponded with a national mass smallpoxvaccination campaign utilizing specially con-

WHO IntensifiedSmallpox EradicationProgramme started

2200

2000

1800-

1600-

1400-

1200-

1000-

800-

600-

400-

200f-

01961

1963

1965

1967

1969

1971

1973

Fig. 20.3 . Zambia: number of reported cases ofsmallpox, by year, 1961-197 I .

Year Number ofcases

Number ofdeaths

Case-fatalityrate (%)

Number ofvaccinationsa

1956 576 52 9.01957 459 56 12.21958 210 21 10.01959 178 13 7.31960 350 31 8.91961 233 8 3.41962 210 4 1 .91963 1 881 271 14.41964 2 214 189 8.5 1 657 3301965 528 59 11 .2 1 500 0001966 63 10 15.9 1 535 6341967 47 3 6.4 1 183 8361968 33 5 15.2 1 365 5141969 0 - - 1 508 9581970 2b 1 525 5111971 0 1 549 4791972 0 1 400 0001973 0 1 500 000

stituted mobile teams. The programme beganin 1964 in each of 8 provinces under thesupervision of provincial officials . Onehundred and forty vaccinators were recruitedand trained locally and discharged when theteam had completed its work in a given area .They vaccinated at assembly points, usingliquid vaccine. The intent was to vaccinateone-third of the population of each provinceeach year. Vaccinations were performed dur-ing the dry season, from May to November .Despite a serious shortage of transport,limited supervision and inadequate refriger-ation facilities, 1 .66 million vaccinationswere reported to have been given during 1964and 1.5 million in 1965. Take rates amongprimary vaccinees were found to be about80% . This was lower than the take ratesexpected when freeze-dried vaccine was usedbut, considering the logistic problems in thecountry, it was a remarkably good result . Thenumber of reported cases decreased sharply,from 2214 in 1964 to 528 in 1965 .

In January 1966, freeze-dried vaccine,donated by the USSR, began to be employed .That year, another 1 .54 million persons werevaccinated, and the number of cases decreasedfurther to only 63 in 1966 .

The government was committed to small-pox eradication and in March 1967 requestedWHO to provide vehicles, refrigerators andother equipment as well as 4 advisers-amedical officer counterpart for the directorand 3 operations officers to serve in supervi-sory roles, where needed, at provincial level .Between 1967 and 1973, WHO was toprovide 10.6 million doses of vaccine andexpend US$644 146, an outlay which in-cluded WHO salary payments. The WHOmedical officer arrived in November 1967and the 3 operations officers in 1968 . Mean-while, the government staff for the massvaccination campaign was increased from 140to 207 .

Under the new WHO-assisted programme,BCG vaccine was given simultaneously to allschoolchildren and, in two of the provinces,to younger children as well . Between January1966 and the end of 1968, the so-called "firstphase" of the programme was completed-i .e., vaccination with freeze-dried vaccinethroughout the country . The number vacci-nated was roughly equivalent to the estimatedpopulation. In 1968, only 33 cases werereported and smallpox transmission appearsto have been interrupted in December of thatyear.

20. SOUTHERN AFRICA

973

During 1967-1968, the WHO-assistedprogramme changed little in character . Vac-cination was conducted at assembly points ;coverage and take rates were assessed onlyoccasionally ; little was done to improve thesurveillance system. Indicative of the qualityof surveillance is the fact that little is knownabout the last 10 cases reported in 1968,except that 2 were said to have been infectedin Zaire.

Beginning in 1968, the establishedgovernment health units were provided withstocks of vaccine and encouraged to vaccinateall who attended but, as was true in manycountries, these units evinced little interest inundertaking even this most simple ofpreventive measures. Throughout the wholeof 1969, they performed only 91 650 vaccina-tions and many of these were given byprogramme vaccinators who were assigned toclinics. Fully 3 additional years of concertedeffort were required before the staff of thehealth units began to vaccinate significantnumbers of persons.

Although a programme of vaccination hadbeen completed throughout the country, thegovernment decided in 1969 to repeat thenational mass vaccination campaign, usingspecial teams as before. Because smallpox wasstill endemic in neighbouring Zaire, theUnited Republic of Tanzania and Mozam-bique and because the existing health unitswere providing little help, government of-ficials felt that this was the only way that theycould ensure a sufficiently high level ofvaccinial immunity to prevent spread shouldintroductions occur.

The WHO operations officers were as-signed to the provinces bordering on Zaire,and vaccination check-points were estab-lished at the principal border crossings toexamine persons entering the country and tovaccinate anyone without a scar . In someareas, the coverage achieved was assessed byWHO operations officers after the teams hadworked in an area. Throughout Zambia,however, supervision generally remainedpoor, which was reflected in the un-satisfactory performance of vaccinators,who averaged only 40 vaccinations per day.

The repeat mass vaccination campaign wascostly but it did assure the movementthroughout the countryside of vaccinationteams which could detect any cases thatexisted . Between 1969 and 1971, an additional4.6 million vaccinations were performed, theannual average being no more than had been

974


achieved in 1964-1965, before the provisionof WHO assistance.

During 1970, at the midpoint of this repeatround of mass vaccination, a cluster samplesurvey of the country was carried out by staffof the WHO Epidemiological SurveillanceCentre in Nairobi, Kenya, to measure the levelof vaccination coverage . In all, 17 927 personswere examined. The proportion with vaccina-tion scars was found to range from 62% to80 % in the different provinces, but in 5 of the44 districts it was discovered that fewer than60% of the people had ever been vaccinated .By any standard, the programme had not beennotably successful.

The need to recruit at least one experiencedteam to encourage reporting and to inves-tigate each suspected case had been stressedrepeatedly by Ladnyi, the WHO intercountrysmallpox adviser for eastern and southernAfrica, but not until late 1969 was such a teamformed and the first efforts made to ensurethat each of the 429 health units provided aweekly report. Even then, the effort left muchto be desired : as late as June 1970 the WHOmedical adviser to the national programmecommented that a report of a suspected casewas usually followed by immediate investi-gation. The concept that every suspected casewas important was not understood .

Meanwhile, in Zaire, mass vaccinationthroughout the neighbouring Shaba Provincewas completed during 1969, although a fewcases of smallpox were reported each monthin early 1971 . Despite the continuing pres-ence of endemic smallpox just across theborder, only 2 imported cases were detected inZambia, in April 1970. These cases actuallyspent less than a day in the country . Theindividuals concerned-a 4-year-old childand a 7-year-old child-were brought acrossthe river from Zaire by their parents to beexamined at a clinic . They were diagnosed assuffering from smallpox by the staff of theclinic and were promptly sent back to Zaire,

Table 20 .3 . Zambia : age distribution of reported cases of smallpox, 1964-1965 and 1966-1968

but the incident was duly reported to theprovincial health office. These were Zambia'slast known cases.

Not until the beginning of 1971, when therisk of importations seemed to havediminished almost to nil, was a com-prehensive surveillance system finally estab-lished in northern Zambia, near the borderswith Zaire and the United Republic ofTanzania. In these areas each village wasvisited twice monthly by a surveillance agentto detect cases with rash and fever whichmight be smallpox. Additional permanentvaccination posts were established along thefrontiers and many suspected cases wereinvestigated . Because the United Republic ofTanzania detected no cases in 1971 and Zairefound none after June of that year, it is notsurprising that no further cases were dis-covered in the bordering areas of Zambia .

With the conclusion of the second round ofmass vaccination, the number of staff wasreduced and the number of WHO advisersdecreased from 4 to 2. A maintenance pro-gramme was established whereby 15 mobilevaccination teams moved through the prov-inces vaccinating the more remote popula-tions and encouraging vaccination in estab-lished health facilities. In all, 1 .4 millionpersons were vaccinated in 1972 and 1 .5million in 1973, numbers comparable to thosevaccinated by the much larger special vac-cination campaign staff. In the mid-1970s,immunization against several diseases beganto be offered by many of the established healthunits, and monthly reports giving the numberof cases of disease and the number of vaccina-tions performed were received regularly from96 hospitals and 689 health centres andsubcentres .

The age distribution of cases during 1964-1965 was unusual in that 86% of thoserecorded were in individuals aged less than 6years (Table 20.3). This was an unusually highproportion of cases among young children,

1964-1965 1966-1968

Age group(years) Number of cases % Age group

(years) Number of cases %

< I 626 23 < I 40 28I-5 1 733 63 1-4 63 446-14 257 9 5-14 26 18315 126 5 315 14 10

Total 2 742 100 Total 143 100

for which there is no explanation other thanthat it may have been an artefact of reporting .Data for the 1966-1968 period show a moretypical age distribution of cases .

MALAWI, MOZAMBIQUE ANDSOUTHERN RHODESIA

Background

Malawi, Mozambique and SouthernRhodesia together had a population of 18million (in 1970) and a reasonably extensivenetwork of health centres and roads, SouthernRhodesia's being the most fully developed .From 1963, the prevalent form of smallpox inthese countries appears to have been variolamajor, with a case-fatality rate of 5-15% .During the early 1960s, smallpox had been ofspecial concern to the health authorities, andall had organized mass vaccination campaignsemploying mobile teams. Reasonably satisfac-tory control seems to have been achieved .In all, only 142 cases were reported in 1966and 172 in 1967, although the true numberswere undoubtedly much greater becausenotifications in these countries, as elsewhere,were very incomplete.

The recurrence of variola major was arecent development. Variola major had beenprevalent before 1952, but in that year it wasreplaced by variola minor . From 1952 to 1958,for example, Malawi recorded 810 cases butonly 8 deaths. In 1959, both the number ofcases and the case-fatality rate began to

20. SOUTHERN AFRICA 975

increase and by 1961, 1465 cases with 161deaths were reported (Table 20 .4) . The sourceof the strain which infected Malawi was in alllikelihood either neighbouring Zambia or theUnited Republic of Tanzania . In Mozam-bique, a similar change in the prevalentsmallpox strain took place in 1962-1964, atthe time of civil conflict along its border withthe United Republic of Tanzania. In 1963,fatal cases began to be observed in SouthernRhodesia, virtually all of them occurringin the eastern provinces bordering onMozambique .

The civil war in Mozambique played asignificant role in the persistence of smallpoxin these countries. A national independencemovement, which had been established inborder areas in the south of the UnitedRepublic of Tanzania, moved into the 2northern provinces of Mozambique in 1964.In addition to conducting guerrilla warfare,the independence movement established apolitical and administrative structure which,during the following decade, expanded intothe central and north-western provinces . Tocombat this movement, the Mozambicangovernment resettled many of the scatteredrural population into villages which couldbe defended and in which health and edu-cational services could be provided . Thus,village health units capable of reporting casesof smallpox existed throughout the country,but few activities were possible in the sparselypopulated rural areas, including extensivetracts adjacent to the United Republic ofTanzania, Malawi and Southern Rhodesia .

Table 20 .4. Malawi, Mozambique and Southern Rhodesia : number of reported cases of and deaths fromsmallpox and case-fatality rates, 1959-1972

a Cases documented during survey In 1972 .b Nine cases documented during 1972 survey and I during 1977 survey .

Year

Malawi Mozambique Southern Rhodesia

Number ofcases

Number ofdeaths


Number ofcases

Number ofdeaths


Number ofcases

Number ofdeaths


1959 559 23 4 .1 44 0 0 133 0 01960 795 64 8 .1 14 0 0 12 0 01961 1 465 161 11 .0 91 2 2.2 3 0 01962 634 69 10 .9 69 4 5 .8 I S 0 01963 455 57 12 .6 102 7 6.9 38 5 13 .21964 720 55 7 .6 243 24 9.9 200 15 7.51965 226 8 3 .5 115 25 21 .7 40 3 7.51966 88 2 2 .3 19 6 31 .6 35 0 01967 38 3 7 .9 104 32 30.8 30 1 3 .31968 61 7 11 .5 145 15 10.3 10 1 10 .01969 65 4 6 .2 11 0 - 33 2 6 .11970 39a Ia 2 .6 0 - 6 01971 job 0 0 0 0 -1972 0 - - 0 0

976

Vaccination Campaigns

For a number of years prior to 1967, aconsiderable proportion of the population ineach country was reported to have beenvaccinated each year (Table 20 .5), but none ofthe programmes incorporated a system forassessing the level of coverage achieved, andonly in Southern Rhodesia were take ratesregularly appraised .

Freeze-dried vaccine was used only inMozambique, the vaccine having been pro-duced at the Instituto de Investigacao inLourenco Marques (now Maputo). Samples ofthis vaccine were tested by the InternationalReference Centre for Smallpox Vaccine inBilthoven, Netherlands, in 1968 and 1972and found to meet WHO standards . Vacci-nation in Mozambique was offered in hos-pitals as well as in health and first-aid postsand by mobile teams, each of 9 districtshaving 3 or 4 teams which sought to vaccinateone-third of the population each year . BCGvaccination was given simultaneously . Dur-ing 1968, a special campaign was conductedwhich succeeded in vaccinating againstsmallpox half of the 8 million residents,although, because of security problems, 2districts in the north, Niassa and Tete, couldnot be well covered. A repeat campaign wasconducted in 1972, during which, becausehostilities had subsided in Tete District, it waspossible to vaccinate most of the people in thisarea. Although the coverage was not assessed,vaccinial immunity was probably reasonablygood among accessible populations, consider-ing that a large number of people had beenvaccinated and freeze-dried vaccine had beenused. However, immunity was undoubtedlymuch lower among the inhabitants of the

Table 20 .5 . Malawi, Mozambique and SouthernRhodesia: number of reported vacci-nations performed, 1964-1973


large sparsely populated rural areas of thecentral and northern parts of the country .

In Southern Rhodesia, a similar type ofprogramme was conducted, with vaccinationbeing given by mobile teams and in existinghealth facilities . Poliomyelitis and BCG vac-cines were administered simultaneously tochildren . Until 1970, liquid smallpox vaccineproduced in South Africa had been employed .A continuing assessment of take rates amongprimary vaccinees was conducted by localhealth authorities, and these showed 75-90%successful vaccinations-rates which werelower than those obtained with freeze-driedvaccine, but higher than those in mostcountries that used liquid vaccine. The onlyavailable data regarding the prevalence ofvaccinial immunity are from a 1978 govern-ment survey, which found that 74% ofchildren aged 1-6 years and 92% of thoseaged 7-10 years had vaccination scars .In Malawi, a permanent staff of 42

vaccinators regularly travelled by bicyclethrough their assigned regions, givingsmallpox vaccine only ; a 10-man mobile teamwas available for vaccination where outbreaksoccurred . The mobile team worked primarilyin the south, where, after 1965, almost allcases were found. Until 1966, liquid vaccinewas employed ; primary take rates, whenmeasured in the field, were only 25-50% . Theprogramme was not particularly successful, aswas apparent from a survey in 1965, whichshowed that only 360 of 2566 schoolchildren(14%) in and around the capital city hadvaccination scars. In January 1966, freeze-dried vaccine was made available by UNICEFand thereafter only this type of vaccine wasemployed. WHO staff visiting the country in1966 and 1968 found that the supervision ofvaccinators was poor, their productivity waslow and the vaccinial immunity of thepopulation was unsatisfactory . In one area ofsouthern Malawi, in which United StatesPeace Corps volunteers assisted in mass vac-cination in 1968, 50% of the inhabitantsremained unvaccinated at the end of thecampaign. Late in 1969, the governmentdecided to request assistance from WHO inconducting a national smallpox eradicationprogramme, but a better-organized vaccina-tion campaign did not begin until April 1972 .That programme included the administrationof both BCG and smallpox vaccines . Whenthe campaign was launched, surveys in dif-ferent areas showed that 30-60% of childrenaged 0-4 years and 36-76% of those aged

Number of vaccinations (% of total population)

Year Malawi MozambiqueSouthernRhodesia

1964

1 569 000 (40) 1 056 726 (15) 2 495 112 (59)1965 751 413 (19) 2 139 489 (29) 1 371 600 (31)1966 832 201 (20) 1 463 938 (20) 1 109 997 (24)1967 675 390(16) 2 433 705 (32) 1 173 216 (25)1968 768 000 (18) 4 111 960 (53) 1144 930 (23)1969 970 161 (22) 977 281 (12) 977 073 (19)1970

1 265 335 (28) 1 234 986 (15) 1 198 282 (23)1971 525 329 (11) 2 195 546 (26) 1 399 552 (26)1972 562 347 (12) 2 379 761 (27) 1 401 168 (25)1973 489 111 (10) 2 533 968 (28) 1 119 614 (19)

5-14 years had vaccination scars . Only 5months after the programme had begun, itwas stopped by the government on accountof the occurrence of abscesses due to BCGvaccination. It did not recommence untilAugust 1973-almost a year later-but washalted once again, in December 1973, whencholera broke out and the teams were re-assigned to perform cholera vaccination .

Finally, in 1974, an extensive vaccinationcampaign began, long after the last cases hadbeen detected. It concluded in 1976. WHOfinancial support throughout the course ofthe programme amounted to US$311 011 ; inaddition, 7.8 million doses of vaccine weresupplied .

The Smallpox Situation

In the 3 countries under review, informa-tion about smallpox, from 1967 until 1971,when the last known cases were detected, is

x0

WHO IntensifiedSmallpox EradicationProgramme started

Fig . 20 .4 . Malawi, Mozambique, Southern Rhodesia :number of reported cases of smallpox, by year,1961-1972 .

20. SOUTHERN AFRICA

977

sketchy. Undoubtedly, many cases occurredwhich were not reported and some whichwere reported may not have been smallpox.Health authorities at district or provinciallevel in each country usually performed area-wide vaccination when cases were reportedbut rarely did they conduct investigations todetect additional cases or to identify thesource of infection. Ladnyi, during visits toMalawi, tried to persuade the government toinitiate a surveillance programme, but notuntil 1973 was a satisfactory programmeestablished for the investigation of suspectedcases of smallpox. Since there could be nodirect official communication between WHOand the health authorities in Mozambiqueand Southern Rhodesia, a similar effort toencourage proper surveillance in these areaswas greatly delayed. At the end of 1969, someWHO staff began corresponding personallywith university faculty members in Salisbury,Southern Rhodesia, who soon thereafterundertook to examine specimens from manysuspected cases although few epidemiologicalinvestigations were conducted . Not until thespring of 1972 did WHO and the countriesconcerned reach agreement to give Hender-son special permission to visit Mozambique(as well as Angola and South Africa althoughnot Southern Rhodesia) to assess the nature oftheir programmes and to discuss neededsurveillance measures in areas then believedto be smallpox-free . Information aboutsmallpox, even that pertaining to the lastoutbreaks, is thus fragmentary in all thecountries concerned .

Mozambique detected 104 cases in 1967,145 in 1968 and 11 in 1969 (the last occurringin February) (Fig . 20.4). Of the 145 cases in1968, 142 were reported from parts of only 3provinces, all in the north of the country (Fig .20.5). Most of the outbreaks occurred invillages in Tete District, near the border withMalawi, and in Niassa District, which ad-joined endemic areas in the United Republicof Tanzania. The 11 cases detected in 1969were all in Niassa District . Because theguerrilla forces of the independence move-ment continued to travel between Niassa andthe southern part of the United Republic ofTanzania, it is possible that these foci wererelated . This is speculation, however, since inneither country were outbreaks investigatedto determine their sources . Few smallpoxcases were reported in the south of the UnitedRepublic of Tanzania after 1969 but it laterbecame apparent that the disease persisted in

978


border areas of Malawi and Southern Rhode-sia, at least until the end of 1970. In Mozam-bique, however, no further cases were de-tected after 1969 . Because security in many ofthe border areas was problematic, cases maywell have occurred but remained undetected .

In Malawi, all cases after 1966 were re-ported from the south of the country .Southern Malawi presented an especiallydifficult problem. Large numbers of refugeesfrom Mozambique lived in the region, most ofwhom crossed into the country through forestareas rather than at official border crossings .As illegal immigrants, they sought to avoidany contact with government authorities andoften fled into the jungle when teams came tovaccinate. In order to contain outbreaks,villages were sometimes surrounded by apolice cordon to prevent villagers fromleaving the area until all had been vaccinated .In addition, some outbreaks were discoveredduring which variolation had been per-formed, supposedly in order to quell thespread. Cases which were detected werefrequently reported as occurring among refu-gees from Mozambique or residents who hadbeen in contact with them . Whether the casesrepresented new importations or continuingtransmission among immigrants is unknown .Malawi reported only 61 cases in 1968 and 65cases in 1969. In December 1969, the last casewas reported by the health services . No caseswere notified during 1970-1971 .

By early 1972, it appeared that smallpoxtransmission might have ceased in theMalawi-Mozambique area . More than a yearhad elapsed since the last cases had beendetected in Malawi and nearly 3 years sincethe last case had been reported in Mozam-bique. However, neither country was believedto have adequate surveillance programmes

STOP & 13E t ACCINRTI

AGAINST SMALLPtOX .

Aj1t'6' A1_f Mt3E~f =IFaLE 3ELA `1'~

,

Plate 20 .1 . Important foci of smallpox in southernAfrica were situated along the border betweenMozambique and Malawi, which was frequentlycrossed by Mozambicans fleeing the civil war . Theywere stopped and vaccinated if they used the officialcrossing points, but most went along forest trails andso escaped vaccination .

and thus doubts persisted as to whethersmallpox was really absent. WHO staff couldnot participate in confirmatory studies inMozambique but they could do so in Malawi .In April 1972, Dr Ziaul Islam, who hadreplaced Ladnyi as the WHO intercountrysmallpox adviser, undertook a village-by-village field survey in areas of southernMalawi in which smallpox outbreaks hadrepeatedly occurred between 1966 and 1969 .In 5 villages, he discovered 48 individualswith facial pockmarks who had developedsmallpox in 1970 and 1971 (Table 20 .6). Thearea was densely forested, populated withmany refugees from Mozambique, includinggroups which, for religious reasons, refusedvaccination . The first case that he couldidentify in the chain of transmission had

Table 20.6. United Republic of Tanzania, Malawi, Mozambique and Southern Rhodesia: number of cases ofsmallpox, by 3-month period, 1968-1971

a() = Cases by month of onset, discovered during 1972 and 1977 surveys.

United Republicof Tanzania 180 116 93 66 31 30 22 34 3 23 6 0 0

Malawi 29 6 10 16 28 21 9 7 0 (27) (9) (3) (10)Mozambique 8 26 45 66 II 0 0 0 0 0 0 0 0Southern Rhodesia 2 5 3 0 4 0 14 IS 0 0 I 5 0

1968 1969 1970a 1971 3

Jan .- April- July- Oct.- Jan.- April- July- Oct.- Jan .- April- July- Oct.- Jan .-March June Sept . Dec . March June Sept . Dec. March June Sept. Dec. March

District or other division reporting cases

Fig . 20 .5 . Malawi, Mozambique, Southern Rhodesia :location of reported cases of smallpox, 1968-1970 .

become ill in April 1970, and the last inFebruary 1971. The earliest source of infec-tion could not be specifically linked toprevious outbreaks in Malawi althoughoutbreaks had occurred in the same area in thepast. During a vaccination scar survey in theaffected area, Dr Islam found that 61 % ofchildren under 4 years of age, 84% of thoseaged 5-14 years, and 67% of persons aged 15years and over had vaccination scars . Becauseof the proximity of the villages to Mozam-bique, the authorities there were notified .Mozambican teams subsequently undertookan extensive programme of vaccination and


search throughout the adjoining area inMozambique but found no cases . During1977, WHO and Malawian staff undertook amore extensive survey of the entire affectedarea in Malawi. They confirmed Dr Islam'searlier report but failed to detect furtherspread. They did, however, discover apockmarked girl who was said to have becomeill in September 1972, 19 months after thepresumed last case in February 1971 . Exten-sive investigation failed to reveal any othercases among family contacts and eventually itwas concluded that the reported year of illnesswas erroneous. Malawi's last known case is

980

thus thought to have occurred in February1971 in an outbreak which terminatedspontaneously without being detected byhealth staff.

Southern Rhodesia's surveillance pro-gramme was little better than thecorresponding programmes in Malawi andMozambique, and the origin of its lastoutbreaks no less mysterious . SouthernRhodesia reported only 10 cases in 1968(Victoria Province) and 33 in 1969 (19 inManicaland Province and 14 in VictoriaProvince). The outbreaks were all within 100kilometres of the border with Mozambique .Mass vaccination was reported to have beenperformed in the area of each outbreak butonly occasionally did provincial medical of-ficers investigate outbreaks to ascertain thesources of infection. Indeed, as a review ofrecords in 1978 was to show, none of the casesoccurring in 1969 was investigated to deter-mine the source of infection ; a report of 10cases was found which had been received bythe provincial medical officer but had notbeen transmitted to the national authorities .(These cases do not appear in the officialrecords and are not included in Table 20 .4 orTable 20.6 .)

In 1969, Dr Keith Dumbell from theWHO Collaborating Centre for PoxvirusResearch in London and Henderson from


Plate 20 .2 . Variolator's kit obtained in 1966 . Scabs and pustular material were carried in the bamboo stick ;the awl was used for inoculation . Malawi was the only country in southern Africa where variolation was stillbeing practised in the 1960s.

Geneva began to correspond with Dr J. G.Cruickshank, a virologist at the UniversityCollege in Salisbury, to encourage the takingof specimens from cases to confirm thediagnosis and to obtain virus strains forlaboratory study . Subsequently, in March1970, the Secretary of Health of SouthernRhodesia directed provincial medical officersto obtain such specimens, and DrCruickshank, employing electron microscopyand standard virus isolation techniques, be-gan to process a flow of specimens (Swanepoel& Cruickshank, 1972). Throughout most of1970, some of the specimens submittedshowed herpes-varicella virus but noneshowed any poxviruses. No cases were re-ported to WHO from Southern Rhodesiaduring 1970 until 13 August, when a telex

Table 20 .7. Malawi : number of reported cases ofsmallpox, by age group, 1960-19652

a Data by age group not available for 1422 other cases reportedduring this period.

Age group(years)

Number ofcases

< 6 2 079 726-15 528 18

16 266 9

Total 2 873 99

from the government was received in Genevareporting a case of smallpox . Because thenotification had been made under provisionsof the International Health Regulations, offi-cial inquiry to Southern Rhodesia was permit-ted : "Would appreciate receiving urgentlyfurther particulars on source of infection ofrecent smallpox case and confirmation ofdiagnosis. No known smallpox in recentmonths in eastern Africa within 325 miles ofChipinga District [the location of the case] ."The reply, telexed a week later, indicated thatthe case had not been confirmed because thepatient had left the hospital before beingquestioned and was thought to have returnedto Mozambique. The official weekly reportsfrom Southern Rhodesia subsequently reflect-ed no cases ; only much later was the caseadded to the official records.

No other cases were notified until Novem-ber 1970, when the government reported, bytelex, 2 further cases . The existence of thesecases implied that there was a persistent focusof endemic smallpox, and undoubtedly manymore cases had occurred to sustain thechain of transmission. Letters and telegramswere exchanged, but to little avail. SouthernRhodesia was eventually to record officially 6cases in late 1970. Four were reported fromChipinga Town, 25 kilometres from theMozambican border ; 2 of them were consid-ered to have been possible importationsfrom Mozambique but the information avail-able was too vague to confirm this . Theremaining 2 cases were reported from anotherprovince near the border and confirmed byelectron microscopic examination . Their on-set occurred in December 1970 . It was re-ported that the patients had been inMozambique 2 weeks earlier, but again theinvestigation was perfunctory .

Over the succeeding 5 years, Dr Cruick-shank examined 17 specimens taken fromsuspected cases of smallpox and others frompatients with chickenpox and other rash-

Table 20 .8. Mozambique: number of reported casesof smallpox, by age group, 1968

20. SOUTHERN AFRICA

981

producing illnesses . None proved to besmallpox . During 1978, in preparation forcertification, extensive pockmark surveyswere conducted to detect cases that mighthave been missed. Only 1 case was found,which had occurred in mid-1970, some 6months before the last 2 cases were recorded .(This case does not appear in the officialrecords and is not included in Table 20 .4 orTable 20.6)

In summary, only 6 cases of smallpox wereofficially reported by Southern Rhodesianhealth staff during 1970-1971 . Later, another49 cases were discovered during specialsurveys in Malawi and I further case inSouthern Rhodesia. Such investigations aswere carried out suggest that persistenttransmission may have continued throughout1970 and possibly during the early months of1971 in border areas of Mozambique as well asin Malawi and Southern Rhodesia . At allevents, the number of cases was undoubtedlysubstantially greater than the official recordsindicate.

Age Distribution of Cases

Information regarding the age distributionof cases is available for only a proportion ofthe cases from Malawi during 1960-1965(Table 20.7) and for all of those in Mozam-bique in 1968 (Table 20.8) .

Cases in Malawi occurred predominantlyamong children-a characteristic of endemicsmallpox-during the period 1960-1965 . InMozambique during 1968, a larger pro-portion of cases was found among olderpersons, perhaps reflecting the fact that manycases occurred among more isolated groupsliving in sparsely settled areas . However,because reporting in both countries wasincomplete, these data must be interpretedwith caution .

SOUTH AFRICA, BOTSWANA,LESOTHO, NAMIBIA AND

SWAZILAND

Background

South Africa, Botswana, Lesotho, Namibiaand Swaziland are closely related geographi-cally as well as by trade and commerce . SouthAfrica is by far the largest of these countries,with a population of 22.8 million (in 1970) .

Age group(years)

Number ofcases

ova

< 1 24 171-4 44 305-14 42 29

I5 35 24

Total 145 100

982


The others had a combined population ofonly 3.2 million, many of whom were em-ployed in South Africa, principally in mining,or travelled there regularly. An extensive,well-developed network of health services,roads and communication facilities extendedthroughout South Africa ; the other countrieshad fewer resources of this kind .

The persistence of endemic smallpox in thispart of southern Africa can be attributedprimarily to the fact that, for more than 50years, the predominant type of smallpox hadbeen a form of variola minor which was evenless severe and with a lower case-fatality ratethan that in the Americas . Described first inSouth Africa in the late 1800s, it was knownas "amaas" or "kaffir-pox" (see Chapter 5). Itsmild character is illustrated by the fact thatfrom 1922 to 1944, 9122 cases were notifiedin South Africa but only 17 deaths wererecorded. Between 1945 and 1952, however,case-fatality rates tended to approach thoseassociated with variola major in Africancountries to the north. But after 1952, variolaminor again displaced variola major . From1953 to 1971, only 13 deaths attributed tosmallpox were reported, of which 11 occurredin 1964 (Table 20 .9) during an outbreak of 54cases in Port Elizabeth, Cape Province . Thisoutbreak was attributed to an importationfrom Zambia. Evidence that the low case-fatality rate was not an artefact due toincomplete recording of deaths was provided

Table 20 .9 . South Africa : number of reported casesof and deaths from smallpox and case-fatality rates, 1951-1972

a . . = data not recorded .

when variola minor spread from South Africato Botswana in 1971 . There, cases and deathswere much more carefully documented . Of1122 patients, only 2 died.

Continuing vaccination campaigns em-ploying liquid vaccine produced in SouthAfrica had been in progress in each of thecountries for many decades . The programmeswere intended primarily to prevent large-scale outbreaks of variola major should it bereintroduced rather than to control the rela-tively innocuous variola minor, against whichthe vaccine also provided protection .

Until 1972, little information regardingthe epidemiology of smallpox and the controlprogramme in South Africa was available toWHO. That which was available was gleanedfrom a monthly infectious diseases bulletinpublished by the government and occasionalreports of outbreaks sent to WHO by theSecretary of Health, in partial conformitywith the International Health Regulations .Information regarding the geographical dis-tribution of cases would have been helpful butthe reports listed cases only by month and byracial group .

Data from South Africa, such as they were,were regularly included in published reviewswhich appeared in the Weekly epidemiologicalrecord. As country after country in Africabecame free of smallpox, South Africa'sdubious distinction as one of only a fewendemic countries became politically intoler-able to its authorities . Although the diseasewas not a public health problem, South Africabegan to take an interest in smallpox in 1970and commenced an intensive vaccinationcampaign in the endemic areas . Surveillancewas incomplete, and it is therefore uncertainwhen transmission was actually interrupted .The last known endemic case occurred on 3May 1971 .

Only a few months later, neighbouringBotswana began to detect cases . Perfunctorycontrol measures were taken but smallpoxcontinued to spread. Not until May 1972,almost a year later, was an adequate pro-gramme begun. By then, the disease hadspread widely across the country . Smallpoxpersisted in Botswana until November 1973 .

Lesotho, Namibia and Swaziland

Events in South Africa and Botswana aredescribed in greater detail later in thischapter . Smallpox occurrence and programme

YearNumber of

casesNumber ofdeaths


1951 1434 a -1952 80 17 21 .31953 14 0 01954 7 0 01955 27 0 01956 4 0 01957 0 0 -1958 0 01959 0 0 -1960 65 0 01961 8 0 01962 103 0 01963 254 0 01964 302 1I 3 .61965 191 I 0 .51966 256 0 01967 43 0 01968 81 0 01969 246 0 01970 121 0 01971 10 I 10 .01972 I 0 0

activities in Lesotho, Namibia and Swazilandmay be briefly summarized . Namibia(population in 1970, 1 .04 million) was one ofthe most sparsely inhabited countries insouthern Africa ; its last known case ofsmallpox was reported in 1956 . Vaccinationprogrammes employing mobile teams whichadministered poliomyelitis and BCG vaccinesas well as smallpox vaccine were well estab-lished and had been operative for many years.Because smallpox transmission had been in-terrupted throughout western South Africaand Angola by 1960 and in Botswana in 1964,the risk of importations was small. Even the1971-1973 epidemic in Botswana posed littlethreat because the outbreaks were con-centrated in the eastern part of that country,separated from population centres in Namibiaby hundreds of miles of desert . Consequently,no special activities were undertaken inNamibia during the Intensified Programme .

Swaziland was first visited by Ladnyi in1968 and Lesotho in 1970 to assess the statusof their activities and to offer such assistancefrom WHO as might be required. Lesotho(population in 1970,1 .06 million), after manyyears of freedom from smallpox, experiencedan outbreak of 84 cases in 1961 . The outbreakextended through June 1962, 52 cases beingreported that year. No deaths occurred . In1961, 700 000 persons were vaccinated in a 3-month mass campaign and, thereafter, mobileteams supported by UNICEF vaccinatedbetween 50 000 and 150 000 people each year,administering liquid smallpox vaccine sim-ultaneously with BCG vaccine . In 1970,WHO began to provide freeze-dried smallpoxvaccine for the programme. No further caseswere found. Swaziland (population in 1970,426 000) began experiencing smallpox out-breaks in 1963, its first since 1950. From1963 to the end of 1966, 182, 517, 85and 73 cases were notified for the respectiveyears, but only 9 deaths were reported duringthe entire period . How many of these weregenuine cases of smallpox is unknown . Of aseries of 73 cases diagnosed as smallpox byauxiliary health workers, 55 were sent tohospital but none was confirmed clinically assmallpox by the physicians who saw them . Inareas in which outbreaks occurred, between44 000 and 90 000 vaccinations were per-formed each year from 1963 to 1966, usingliquid vaccine produced in South Africa. InSeptember 1967, a UNICEF-assisted massvaccination campaign began, employingBCG and freeze-dried smallpox vaccine .

20. SOUTHERN AFRICA

983

Between 1967 and 1972, when the masscampaign concluded, between 34 000 and64 000 persons had been vaccinated each year .Thereafter, vaccination was performed by thehealth centres. A survey in 1970, 3 years afterthe programme had started, revealed that only51 % of persons under 15 years of age and20% of those aged 15 and over had vaccina-tion scars. The year in which smallpoxtransmission was interrupted in Swaziland isunknown. Twenty-five cases were reported toWHO in 1967, 20 in 1968, and 24 in 1969 .Because of this, Swaziland was originallylisted as an endemic country. However,government records reviewed duringcertification activities show no cases after1966 and no one at that time could be foundwho knew anything about the cases that weresaid to have occurred between 1967 and 1969 .Whether these cases represented clerical erroror were indeed cases of smallpox could not beascertained . As in most countries of southernAfrica, smallpox transmission had ceasedspontaneously during the course of anindifferently executed vaccination campaign .When surveillance programmes eventuallybegan, no cases could be found .

South Africa

Richly endowed with natural resources andwith a large and expanding industrial base,South Africa had many of the attributes ofdeveloped countries in temperate climates .Almost half of South Africa's population of22.8 million (in 1970) lived in urban areas .Preventive health services were administeredby regional medical directors, 2 of whom wereassigned to the 2 larger provinces (Cape andTransvaal) and 1 each to the 2 smaller(Orange Free State and Natal) . They, in turn,oversaw the work of medical officers of healthin each local authority. The pattern of vac-cination activities differed somewhat fromprovince to province but, in general, allprovided vaccine through health centres andclinics, and supplemented this in rural areasby mobile teams which performed vacci-nations at collecting points . Poliomyelitis,smallpox and BCG vaccines were adminis-tered to young children and smallpox vaccineto older children and adults . The smallpoxvaccine, until 1970 a liquid vaccine, wasproduced at the State Vaccine Institute inCape Town . Vaccination was also given to allchildren at school entry, and to the 100 000 or

984


so men who came each year to work in themines. From 1968 to 1975, between 600 000and 900 000 persons received smallpoxvaccine each year through governmentfacilities. The number of vaccinations wassmall in proportion to the population, but thetotal did not include those, said to be many,that were provided by private physicians .Reporting from the more than 10 000

health units which regularly saw patients wasthought to be reasonably good, but becausesmallpox in South Africa was so mild, thegovernment authorities believed that manypersons with smallpox did not seek medicalattention and so did not come to the attentionof the health services. Teachers and heads offamilies were also supposed to report caseswhen they occurred but their level of com-pliance was uncertain, especially in areas inwhich religious sects objected to vaccinationof any type.

Information about smallpox was veryincomplete for other reasons . Responsibilityfor health problems, as well as the in-vestigation and control of outbreaks ofsmallpox and other diseases, was regarded as aprovincial responsibility, and in the prov-inces, as mentioned above, this function wasprimarily discharged by local medical officersof health. Diligence in the investigation ofcases and the conscientiousness with whichnotifications were forwarded varied from areato area . Since the mild variola minor causedthe provincial health authorities littleconcern, not much time was devoted to theinvestigation or control of outbreaks . Theproblem was compounded by a nationalmorbidity reporting system considered to beso unsatisfactory that in 1970 a complete

Table 20 .10 . South Africa : number of reportedcases of smallpox, by province, 1960-1972

a Case imported from Botswana .

Fig . 20 .6 . South Africa : number of reported casesof smallpox, by year, 1961-1973 .

restructuring of the system was begun .Pending completion of this effort, nationalmorbidity reports ceased to be published inMarch 1970. Until 1978, further data regard-ing cases and their geographical location, asnotified nationally, were not made availableto WHO. When reviewed by WHO in 1978,reports revealed that the Transvaal accountedfor most of the cases after 1960 and for all but41 of the 502 cases reported after 1966 (Table20.10) .

South Africa reported only 43 cases toWHO during 1967, and 81 cases in 1968 .Because so few cases were being reported in acountry in which health services were soextensive, WHO had originally assumed thatthese cases must have occurred followingimportations and had provisionally classifiedSouth Africa as a non-endemic country .

In 1969, however, the number of reportedcases increased (Fig . 20.6 ; Table 20.10) .Because communication with South Africathrough the usual official channels was notpossible, Henderson addressed a personalletter to the Secretary for Health on 27August, noting that as of that date : "SouthAfrica now accounts for about 10% of allcases recorded in Africa this year" and askingfor a fuller statement of the epidemiologicalsituation as well as a description of theproblems being encountered in controllingspread. By the end of that year, 246 cases hadbeen reported to WHO.

A reply was not received until February1970. In his letter addressed to Henderson atWHO, the Director of Medical Servicesshowed a dismaying lack of understanding of

Year CapeOrange Free

State Natal Transvaal Total

1960 IS 12 0 38 651961 0 I 0 7 81962 0 0 1 102 1031963 0 1 35 218 2541964 54 1 54 193 3021965 0 0 16 175 1911966 0 0 14 242 2561967 0 0 0 43 431968 0 0 0 81 811969 0 15 26 205 2461970 0 0 0 121 1211971 0 0 0 10 101972 0 0 0 la la

the epidemiology of smallpox . He assertedthat the cases were sporadic and explainedthat, with variola minor, "very mild unde-tected cases and subclinical cases, harbouringthe virus in their tonsils, the lymph follicles ofthe tongue and pharynx are liable to spreadthe disease to every person not vaccinatedagainst smallpox. Due to this mode of spread,a population with a successful vaccinationrate of more than 80% is not protected ." Heindicated that mass vaccination would con-tinue in order to limit the spread of disease. Inreply, Henderson pointed out that in Brazil,in which variola minor was also endemic,"smallpox is transmitted only by cases withdefinite lesions of smallpox and during theperiod . . . of rash . . . and that 80-90% of casescan be traced to personal contact in a house ."The favourable experience of other countriesin investigating and containing each out-break was noted and procedures for outbreakcontainment were described. What effectthis correspondence had is unknown .

As it was later learned, the most importantstimulus which precipitated a more vigorousprogramme in South Africa was the WHODirector-General's report on smallpox eradi-cation, prepared as a document (EB45/16 ;dated 1 December 1969 but never publishedin WHO's Official Records) for the forty-fifth session of the Executive Board inJanuary 1970 and obtained by South Africa .The report stated

"Of the endemic countries in Africa, SouthAfrica and Ethiopia are the only ones which havenot yet initiated eradication programmes . Thenumber of cases recorded this year by South Africamore than doubled [246 cases in 1969 comparedwith 81 cases in 1968] . . . However, littleadditional information is available . . . Thecontinuing reservoir of smallpox in South Africaand Ethiopia is of increasing concern toneighbouring countries, most of which havebecome, or are rapidly becoming, smallpox free . . .With only three known exceptions, freeze-driedvaccine of satisfactory potency, stability and purityis now used in all endemic countries . However, inSouth Africa, liquid vaccine continues to beemployed . . ."

South African health officials were angeredby the report, considering it to be unfair forthree reasons. The first was that the report andthe tables of data referred to smallpox onlygenerically, drawing no distinction betweenthe severe variola major of Asia or many othercountries of Africa and the mild form ofvariola minor present in South Africa. This,

20. SOUTHERN AFRICA

985

however, had been a policy followed by WHOsince the inception of the programme becausethe mandate of the World Health Assemblywas the eradication of smallpox of whatevervariety . The second was the issue of whetheror not South Africa could be said to have aneradication programme . As the healthauthorities viewed it, an effective vaccinationcampaign was being conducted throughoutthe country and local authorities were ex-pected to control outbreaks when these oc-curred. In WHO's view, however, an eradica-tion programme had as its objective thecomplete interruption of smallpox transmis-sion, an unrealistic aim as seen by the SouthAfrican Director of Medical Services . Thethird reason was the emphasis on the use offreeze-dried vaccine-clearly of importancein tropical countries in which ambient tem-peratures were high and refrigerated storagewas scarce. In South Africa, however, ambienttemperatures were not so high and refriger-ated storage for vaccine was not considered aproblem. WHO's emphasis on the need forfreeze-dried vaccine in endemic areas wasbased on the recognition that even whenrefrigerated storage was adequate, health andmedical personnel, even in industrializedcountries, often failed to preserve vaccinesproperly .

Although highly sceptical that otherAfrican countries were making as muchprogress as was claimed, the South Africanhealth authorities decided early in 1970 totake additional measures to control smallpoxand, by so doing, avoid the expected criticismof other independent African countries . Aspecial programme was launched to producelarge quantities of freeze-dried vaccine ; byMay, all mobile vaccination teams were usingthis. The vaccine was said to meet WHOstandards although it was not examined by aWHO reference laboratory. By the end of1970, liquid vaccine was being provided onlyto private practitioners .

In June 1970, an intensified systematicvaccination campaign was begun in thenorthern Transvaal, from which mostsmallpox cases were reported. It was termed ahouse-to-house campaign although, forconvenience and efficiency, vaccinatorsusually assembled persons from a group ofneighbouring houses. By the end of the year,more than 350 000 persons had beenvaccinated. This represented only a smallproportion of the 6.3 million people thenresident in the province, although coverage in

986


the infected but sparsely populated northernareas was said to be high .

By the end of June 1970,117 cases had beenreported to WHO, but thereafter none wasnotified until December (4 cases) and again inJanuary 1971 (7 cases) . As was learned onlymuch later by WHO, all were in the Trans-vaal, not far from the border with Botswana(Fig. 20.7). Reports from South Africa thenceased. Repeated inquiries were made byWHO officials and others in South Africaafter January 1971, under the provisions ofthe International Health Regulations, askingfor confirmation that no further cases hadoccurred, but there was no response . It wasunclear whether there were indeed no cases orwhether the government had decided not toreport any more cases of smallpox to WHO .

In June 1971, Botswana reported a case ofsmallpox in Gaborone, the capital, but 2weeks later asserted that the case had actuallybeen chickenpox . In August, additional caseswere reported and these were confirmed assmallpox by laboratory examination . Theinformation was promptly relayed to SouthAfrica and Southern Rhodesia, and teamsfrom both countries immediately went toborder areas to conduct intensive vaccinationcampaigns. The Botswana outbreak contin-ued but only 1 case is known to have beenreimported into South Africa-in a labourerwho became ill on 14 February 1972 .

The question of concern in the autumn of1971 was how and where smallpox transmis-sion was being sustained in the South Africa-Botswana area . As has been noted, SouthAfrica had reported 11 cases during the 2-month period, December 1970 to January1971, after 5 months during which no caseshad been notified . Following this, 7 monthshad elapsed before cases were confirmed inBotswana. It was certain that many additionalcases had occurred during these two intervalsin order to sustain the chain of transmission .Discovery of the infected area was important.Botswana, whose surveillance system waspoor, was a candidate area but, because of theletter from South Africa's Secretary forHealth, the programme in the latter countryhad to be regarded with suspicion. WHOHeadquarters staff believed it imperative thata visit should be made to South Africa, as wellas to Angola and Mozambique, to assess thesituation. This was proposed on the groundsthat such contact with South Africa waspermissible under the terms of a resolutionadopted by the WHO Executive Board

Fig . 20 .7. Southern Africa : areas known to havehad endemic smallpox, 1970-1971 .

(EB45.R20), endorsed by the Twenty-thirdWorld Health Assembly in resolutionWHA23.46, which had requested the Direc-tor-General "to continue to take all necessarysteps to assure the maximum co-ordination ofnational and international efforts" . This, itwas felt, implied licence to visit South Africa .The proposal was discussed at length andeventually agreement was reached betweenWHO and the South African governmentthat Henderson should visit South Africa,which he did in June 1972 .

In the Transvaal, he found a well-organ-ized vaccination campaign in progress, withattention being given to the detection andlaboratory confirmation of suspected cases .During 1972, only a single importation fromBotswana had been detected, but healthofficials were alert because they believed therewould be more if not from Botswana,perhaps from Angola or Mozambique, whichthey believed continued to harbour endemicsmallpox even though neither reported cases .However, when Henderson endeavoured

to obtain epidemiological data regarding thecases reported in 1971, it became apparentthat there had been many more cases ofsmallpox than had been reported to thenational authorities. Official records at thattime showed only the 7 cases which hadoccurred in January 1971, in a hospital some300 kilometres from the border with Bot-swana. On the other hand, -a review of records

at the National Institute for Virology, Sand-ringham-the diagnostic reference centre-showed 10 poxvirus isolations during 1971,the last from a patient who became ill on 3May 1971 .

The laboratory itself, well equipped andwell staffed, was in part inadvertently respon-sible for problems in smallpox control . Itemployed an unorthodox approach to theexamination of specimens . Standard virologi-cal technique called for the isolation of viruson the membrane of fertile hens' eggs. Byvisual examination of the pocks that grew,variola virus could readily be distinguishedfrom vaccinia virus. At the Institute, thespecimens were grown in tissue culture inwhich, if virus growth occurred, it wasimpossible to discriminate with certaintybetween variola virus and vaccinia virus .Accordingly, the laboratory reported onlywhether or not a virus of the "vaccinia-variola virus group" had been isolated . Thelaboratory director's view was that whoeversent the specimen should be able to make aclinical distinction between smallpox anddisseminated vaccinia, and thus he saw noneed to differentiate the viruses by laboratorystudy. Recipients of the reports, however,sometimes misinterpreted them and reclassi-fied cases of smallpox as vaccinia .

Cases and outbreaks were notified to theregional medical directors by local healthofficials, who controlled any outbreaks thatwere found with varying levels of diligence .At neither the national nor the provinciallevel was there a health official responsible forensuring that the outbreaks were properlyinvestigated and contained . In no instancehad an effort been made to trace the spread ofsmallpox or to define endemic areas . Reportsof variola virus isolations by the referencelaboratory were made known only to thepersons submitting the specimens ; provincialofficials were not provided with copies of thereports.

Following Henderson's visit in June 1972,health officials endeavoured to reconstructthe epidemiological pattern of spread ofsmallpox during 1971 . This was important,for if it could be shown that the cases hadbeen closely related and the outbreaks con-tained, there would be greater assurance thatSouth Africa by 1972 was indeed free ofsmallpox. Conversely, if the cases had beenscattered and unrelated to each other, wide-spread and perhaps continuing endemicitywas implied .

20. SOUTHERN AFRICA

987

The investigations eventually revealed thatsmallpox had indeed persisted in South Africauntil at least May 1971, all the cases occurringafter February having acquired the infectionat a hospital about 100 kilometres north ofPretoria, in the Transvaal. As far as theoutbreak could be reconstructed, 3unvaccinated children from a village 30kilometres distant were hospitalized withtypical smallpox in January and February1971 and the diagnosis was confirmed byvirus isolation . The mother reported that herother 4 children, as well as a number ofchildren in the vicinity, had been ill with asimilar disease . Three additional childrenfrom the same village were admitted withsmallpox during January and February, al-though no specimens were collected. On 26March, a child hospitalized with tuberculousmeningitis and receiving steroid therapydeveloped a rash at first thought to be drug-induced. Specimens were taken and theNational Institute for Virology reported theisolation of a virus of the vaccinia-variolagroup. The report was misinterpreted and itwas concluded that the child had experienceddisseminated vaccinia . The patient died on 3April. Three additional cases occurred inpreviously hospitalized children on 12,14 and19 April respectively, all of which wereconfirmed by virus isolation . The RegionalMedical Director, who was asked to inves-tigate, reported as follows :

"The suspected outbreak has occurred in the TBward. One death [not officially notified] isattributed to the disease which had been diagnosedalso in 3 other children who were examined . Inaddition, 3 cases of healing chickenpox wereexamined. According to my information, the latterdisease has been "endemic" amongst children inthis ward for many months . That is to saychickenpox has been diagnosed also amongst otherchildren who have no visible lesions now andalso in children who have been discharged al-ready . . . Vaccination of patients and person-nel . . . carried out 7 April did not give asatisfactory percentage of takes . . . The ward wasplaced in quarantine only this week . Therefore, alist was compiled of all inmates and also of allpatients discharged . . . The homes of all will bevisited by departmental field staff ."

A large hospital-based outbreak ofsmallpox and possibly of chickenpox hadobviously been in progress for at least 2months. Extensive vaccination campaignswere conducted subsequently in the many

988


areas from which the hospital patients had

Table 20 .11 . Botswana: number of reported casescome. Three additional cases were found, allof whom had been infected at the hospital : achild who had been hospitalized became ill on3 May, and 2 labourers who had been seen inthe outpatient department 2 weeks earlierbecame ill in March on a farm 100 kilometresdistant . In all, 10 cases and 1 death appear onthe official records for 1971 but, as is apparentfrom this account, there were at least 20 casesand possibly many more . Fortunately, the out-break occurred at the end of the summer,the low point in seasonal transmission, sothat despite greatly delayed containmentmeasures, smallpox spread slowly and trans-mission was soon interrupted.

In South Africa, as in other countries ofsouthern Africa, extensive vaccination ratherthan an organized surveillance-containmentprogramme served to interrupt transmission .During the continuing vaccination cam-paign, no further cases were detected andnone was reported by the 11 000 reportingunits. Among 77 specimens submitted to thelaboratory over the period 1972-1977, only 1further isolation of the "vaccinia-variolagroup of viruses" was made, the specimenconcerned being from the case (see above)that was imported from Botswana in 1972.

Botswana

Botswana, which became independent in1966, is large but sparsely populated, the greatKalahari desert extending over the south-west portion of the country and occupyingmore than half the land area. Over 80% of itspopulation of 623 000 (1970) lived along astrip of land in the south-east, not more than200 kilometres wide, adjacent to the Trans-vaal Province of South Africa. Travel betweenBotswana and South Africa was frequent ;population movement within the countrywas extensive and followed an unusualpattern. A large proportion of the populationmaintained 3 dwellings : one in a village, asecond at a cattle post and a third in a farmingarea. Family members spent time each year inthe different locations, which were oftenwidely separated. Moreover, an estimatedone-third of the adult males left rural areaseach year seeking employment in thecountry's urban areas or in South Africa.Government health facilities were com-paratively numerous ; in 1966 there were 7ho ital , 73 clinics and 65 health ost

of smallpox, 1959-1974

Several missionary groups also provided me-dical care.

In this small and scattered but highlymobile population, smallpox was character-ized by periodic outbreaks followed by longintervals with few or no cases . An outbreak of175 reported cases and 34 deaths in 1964was controlled by a mass vaccination cam-paign and during the following 6 years only 1case was notified (Table 20 .11).

Because Botswana was believed to besmallpox-free when the Intensified SmallpoxEradication Programme began and becauseadjacent countries were reporting few or nocases, the development of a special pro-gramme was not considered by WHO to be ofhigh priority-if it was required at all. Astime passed, the apparent need for a pro-gramme diminished. Neighbouring Namibiaand Angola reported no cases and Zambiabecame smallpox-free in 1968 . The only other

Table 20.12. Botswana: number of smallpox vac-cinations performed, 1965-1977

a . . = data not recorded.

YearNumber of

cases

959 51960 311961 361962 81963 21964 1751965 01966 01967 I1968 01969 01970 01971 361972 1 0591973 271974 0

Year Number ofvaccinations

1965 a1966 47 6971967 48 8071968 39 2531969 19 5821970 46 0001971 112 0001972 402 0001973 149 0001974 68 8761975 93 3451976 62 2351977 95 660

adjacent countries notifying cases, South Af-rica and Southern Rhodesia, reported so fewin 1967-1968 that WHO suspected that theywere the result of importations rather than ofendemic transmission . By the end of 1969,however, the number of reported cases inSouth Africa had increased so greatly that itseemed certain that endemic smallpox waspresent there . Although the governmentinformed WHO that some of the cases were inTransvaal Province, their exact whereaboutswere not revealed . Only in 1972 did it becomeknown that virtually all the reported caseshad occurred in the Transvaal, many near theborder with Botswana .

Ladnyi paid his first visit to Botswana inJanuary 1971 to discuss the status of itsvaccination campaign and the assistance thatWHO might be able to offer. After Bot-swana's mass vaccination campaign of 1964,some vaccination activities had continued(Table 20 .12). Liquid vaccine from SouthAfrica had been employed up to the end of1969, and thereafter freeze-dried smallpoxvaccine, also purchased from South Africa,was used . Vaccinations were given by mobileteams in 3 of the 6 health districts and offeredby hospitals and clinics throughout thecountry. However, the health facilities for themost part vaccinated persons leaving forSouth Africa and Zambia, both of whichcountries required certificates of vaccination .The number vaccinated each year was equiva-lent to no more than 5-10% of the popula-tion. The proportion of successful vaccina-tions is unknown but was probably not higheven when freeze-dried vaccine began to beused. The freeze-dried vaccine was providedin 100-dose containers and was normally usedfor 1-2 weeks after reconstitution, althoughits potency would have fallen to nil within2-3 days .

Ladnyi found that 80% of the pre-schoolchildren had no vaccination scar, and in aschool near the capital whose pupils hadrecently been vaccinated by a mobile team,only 136 of 334 children (41 %) had avaccination scar. Better handling of thevaccine was obviously needed and he pro-vided appropriate advice.

Ladnyi was concerned that smallpox mightbe imported, and his principal recommenda-tion was that every suspected case of smallpoxshould be treated as an emergency and allnecessary containment measures carried outwith a minimum of delay. He recommendedthat a specimen should be taken from each

20. SOUTHERN AFRICA

989

suspected case and sent to WHO Head-quarters for examination ; meanwhile thesuspected case should be dealt with as thoughit were smallpox. In a country in whichvaccinial immunity was so low, there was aspecial need for prompt action . The govern-ment requested vehicles and vaccine in sup-port of the programme, a request which wasforwarded to the WHO Regional Office forAfrica.

On 1 June 1971, only 5 months afterLadnyi's visit, a cable was received in Genevafrom Botswana reporting a case of smallpox .At that time, no cases had been reported fromanywhere in southern Africa since January,although it was learned later that cases inSouth Africa continued to occur throughMay. Cables sent on 4 and 8 June fromBotswana indicated that the case was in apatient already hospitalized in Gaborone, andthat it had been confirmed virologically atSouth Africa's National Institute forVirology .

Urgent action was indicated . However,permission for WHO Headquarters staff tovisit a country required the prior agreementboth of the WHO regional office concernedand of the country itself. Henderson immedi-ately telephoned the regional office inBrazzaville to point out the urgency of rapidcontainment and of a thorough investigationand to propose that an experienced epide-miologist from Headquarters should visitBotswana immediately . The regional officecontacted Botswana and, on 16 June, reportedthat a cable had been received from thegovernment indicating that the situation wasmisunderstood, that the case had turned outto be chickenpox, and that no visit wasrequired . A return telex from Geneva toBrazzaville again urged an early visit by aWHO adviser in view of the fact that the casewas said to have been confirmed by laboratoryinvestigation . The regional office repliedthat such a visit was not considered advisable .

On 27 August, additional cases of small-pox were reported from Botswana, and speci-mens were sent by the government direct toGeneva. By 6 September, the WHO RegionalReference Centre for Smallpox in Atlanta,USA, had confirmed the isolation of smallpoxvirus. This caused a flurry of telex messagesand letters between Geneva and Brazzaville .Headquarters staff repeatedly urged an emer-gency visit by Arita, pointing, out that theBotswana focus presented a continuing threatto Botswana as well as neighbouring coun-

990

tries and noting that this was clearly as muchan international as a national problem . Theregional office requested more informationfrom Botswana and asked whether WHOassistance was required .

On 7 September 1971, a letter was receivedin Geneva addressed to the Chief of theSmallpox Eradication unit from the Directorof Medical Services of Botswana. Contrary tothe cabled information received by the re-gional office, he reported that in May a 3-year-old child, hospitalized for tuberculosis,had developed smallpox and that a second casehad been detected in a government employeein Gaborone on 16 August. Specimens fromboth had been confirmed as "vaccinia-variolatype virus" by the South African NationalInstitute for Virology. The second case hadbeen vaccinated during a June vaccinationcampaign in Gaborone but showed no scar.The Director of Medical Services noted that" . . . no source of infection has been identified .There must, however, be a focus of infectionsomewhere".

On 20 September, Botswana requested asupply of freeze-dried vaccine which wasimmediately sent from Genevaand anoperations officer to organize a vaccinationcampaign. However, as a new intercountrysmallpox adviser, Dr Islam, had just replacedLadnyi, whose current term of service inWHO had expired, he was sent instead.Unfortunately, despite his experience in thecontrol of communicable diseases, he hadnot yet had direct experience with smallpoxeradication and had not yet been briefedregarding techniques for surveillance andcontainment .

He arrived for a 15-day visit on 8 Octoberby which time 3 additional smallpox cases hadbeen detected and a fourth suspected case hadbeen admitted to hospital. He was unable totrace the sources of these cases . The cases hedid identify were in people who presentedthemselves at the hospital, and he indicatedthat "there is strong evidence that a smallpoxfocus exists . . . in the southern part of CentralDistrict . . . the investigations do not supportthe notion of recent importation". A massvaccination campaign was said to have beenconducted but, in fact, only 38 600 vaccina-tions had been recorded between January andAugust 1971. In the area of the smallpoxfocus, he found that 80% of 1767 primary-school children and 60% of 541 pre-schoolchildren had vaccination scars . In adjacentareas, however, only 20% of those aged 0-6


years had ever been vaccinated . He recom-mended a mass vaccination campaign in theprimarily infected area, offered advice to thegovernment regarding vaccine handling andvaccination technique and stressed theimportance of surveillance. At this time, thesewere the only known cases of smallpox in theentire WHO African Region, the other coun-tries in the African continent in which thedisease was still endemic, Ethiopia and theSudan, both then being in WHO's EasternMediterranean Region .

Cases continued to be reported from Bot-swana and all specimens sent for examinationto the WHO collaborating centres wereconfirmed as smallpox, but no informationwas provided by the government as to whatwas being done to control the spread of thedisease . Faced by frequent and increasinglyurgent requests from WHO Headquarters torespond to Botswana's request for anoperations officer, the regional office couldonly reply that no action could be taken unlessit received an official application from thegovernment .

In November 1971, an unexpected op-portunity arose that permitted directcommunication with Botswana . Mr JohnPhillips, the Resident Representative of theUnited Nations Development Programme inBotswana, stopped in Geneva on the way backto his duty station . After a full discussion ofthe problem with WHO staff, it was agreedthat he would discuss it with governmentofficials and ask them to submit a formalrequest to the regional office for the im-mediate assignment of an operations officer .The request was made forthwith, and DrPierre Ziegler, in charge of smallpox eradica-tion in Zaire, was asked to make available hismost experienced operations officer, MrGarry Presthus (see Chapter 18, Plate 18 .5) .His transfer was not, however, arranged untilthe end of February 1972, nearly 9 monthsafter Botswana had notified its first case .

On arrival, Mr Presthus, with his counter-part, Mr J . B. Sibiya, Senior Health Inspectorfor Botswana, rapidly set in motion a massvaccination campaign and a programmewhich, unique among the programmes ofsouthern Africa, emphasized the prompt de-tection of cases and their containmentthrough vaccination. More than 18 monthswould elapse, however, before transmissioncould be interrupted .

Within a month of his arrival, Mr Presthushad met the director of the Botswana Red

Cross, Ruth Seretse Khama, to explain theimportance of smallpox eradication in Bot-swana and its significance for the globalprogramme. In mid-April 1972, her husband,Sir Seretse Khama, the President of Bot-swana, had signed a special bill allocatingUS$25 000 from the government budget .Although not a large sum in comparison with


Plate 20 .3. A : Joseph B . Sibiya (far left), Senior Health Inspector, with one of Botswana's 4 surveillanceteams. B: Many cases of smallpox were discovered in remote cattle posts in the Kalahari desert by the teams .

funds provided in some other eradicationprogrammes, this represented a substantialcommitment for Botswana .

Using such vehicles as could be borrowedfrom other programmes, Mr Presthus and MrSibiya formed 4 teams to contain outbreaks inknown foci and to encourage the network ofhealth facilities to begin vaccinating both

992


people attending clinics and the inhabitantsof nearby villages (Presthus, 1974) . By earlyMay 1972, forms had been prepared to be usedfor weekly reports from each health unit .Volunteers of all types offered assistance.

Field investigations conducted duringMarch documented 36 cases which had oc-curred during 1971, the first in March nearthe South African border. Mr Presthus be-lieved that there had been many more cases,but with new cases being detected daily therewas no time to document further the previousyear's experience .

In 1972, the number of reported casesincreased to 63 in April and to 66 in May(Table 20.13). In that month, one of the caseswas reported from Ngamiland, in the north-western part of the country, an area of greatconcern because of the frequent movement ofrebel forces between it and areas in south-eastern Angola which were only partiallyaccessible to the government of Angola. Asurveillance team was hurriedly sent to thearea, but fortunately there was an able DistrictMedical Officer, in Ngamiland, Dr NicholasWard, who had already organized the healthstaff for extensive vaccination and searchactivities. Only 5 other cases were eventuallydetected in Ngamiland. A year later Dr Wardwas recruited by WHO, which he served withdistinction in smallpox eradication work inBangladesh and India .

The increase in the number of cases in Apriland May 1972 was of profound concern .Although little was known of past seasonaltrends of smallpox in Botswana itself, it wasassumed that more rapid transmission wouldoccur during the cooler months of the year,from June to the end of October . Accordingly,at the end of May, the WHO intercountrysmallpox adviser was directed to assist MrPresthus and Mr Sibiya in surveillance-containment operations .

Hospital and clinic staff meanwhile hadresponded enthusiastically to the request thatthey should vaccinate people in nearby vil-lages, and by the end of July more than

Fig. 20 .8 . Botswana : areas affected by smallpox,by district, at the end of July 1972 .

200 000 had been vaccinated 5 times asmany as were customarily vaccinated in anentire year. Meanwhile, the 3 surveillanceteams sought to detect and contain outbreaks.The investigation of 48 hospitalized casesrevealed 321 others. Because many were beingtraced to Kweneng District (Fig. 20 .8), asystematic search was conducted throughoutthis area, revealing another 355 cases . Virtu-ally all the cases were detected at cattle postsin rural areas, far distant from the clinics andhealth posts. Meantime, a second but lessseriously affected area was found in CentralDistrict .

The number of cases detected increased to121 in June and to 565 in July. Most were inKweneng and Central Districts (Table 20.14) .Analysis of 39 outbreaks comprising 353 casesrevealed an average of 9 cases in each outbreakwith a range of 3-30 cases ; one-fourth of theoutbreaks had persisted for 4 or more genera-

Table 20.13. Botswana: number of reported cases of smallpox, by month, 1971-1974

a () = Cases shown by month of onset. Most of these cases were not discovered until many months later .

Year Jan. Feb. March April May June July Aug. Sept . Oct . Nov . Dec. Total

1971 2 0 0 (I) 0 (2) 1 (2) 2 4 6 8 10 361972 1 4 20 63 66 121 565 133 33 52 1 0 1 0591973a (2) (3) (7) (4) 0 (I) (I) (2) (1) (1) (5) 0 271974 0 0 0 0 0 0 0 0 0 0 0 0 0

20. SOUTHERN AFRICA

993

Although it was the season of hightransmission, the numbers of cases decreasedsharply after July . Meanwhile, in response towarnings about the problem in Botswana,South Africa and Southern Rhodesiaundertook extensive vaccination campaignsthroughout their border regions, and inAngola, military forces were employed invaccinating the inhabitants of large areas inthe south-east. They detected no cases .

Although resources available to the pro-gramme were limited and the population waswidely scattered, relatively high levels ofvaccinial immunity were achieved in less thana year (Table 20 .15) .

The search for cases continued afterNovember 1972 but none was found untilMarch 1973. On 7 March, a 22-year-old manwas admitted to the hospital in Gaboronewith suspected chickenpox, which proved tobe smallpox. A house-by-house search beganin the vicinity of the patient's home ; it wasextended to Gaborone and, finally, to a cattlepost, 40 kilometres away, in which the patienthad spent a night. No other cases could befound until, after 3 weeks of search, aschoolchild identified a person who hadrecovered from smallpox and was beinghidden from the teams. The patient was amember of a Christian sect, known as theMazezuru, which opposed medical treatmentand resisted vaccination.

The search was then focused on Mazezurufamilies, and 19 cases were eventuallyidentified, the first having been infected inlate September 1972 in Kweneng District inan area in which the last cases had beendetected that year . Two slowly spreadingchains of infection had developed : one chainconsisted of 9 cases in Gaborone, of whom allbut the hospitalized patient were Mazezuru ;and one chain of 10 cases in a town 400kilometres to the north, in which 4 Mazezuruhad been infected . The last of the casesoccurred on 13 April 1973 .

Table 20.14. Botswana: number of reported casesof smallpox, population by district,and number of vaccinations per-formed, 1971-1973

a Population estimates as recorded In 1973 . United Nations(1985) data show a total population of 698 000 for Botswana as awhole in 1973 .

tions of disease. The interruption of transmis-sion was difficult, however, because themildness of the disease permitted infectedpersons to travel between their differentresidences, which they did frequently .

Lack of vehicles hampered the work of thesmallpox eradication teams. Four Land Rov-ers had been ordered in February but, despiteefforts to speed their delivery, they did notarrive until November 1972. Nevertheless,the teams organized by Mr Sibiya and MrPresthus worked tirelessly, and by the end ofthe year 402 000 persons had been vaccinated .From July onwards, 83% of the 19 designatedreporting units sent in weekly reports, al-though some of these were not received until1 or 2 months after dispatch because of thepoor postal service. Accordingly, health staffthroughout the country were instructed touse the telephone or telegraph if a case wasfound. However, an analysis of reports at theend of November showed that only 5% ofcases were seen by the health care units, theremainder being detected by outbreakinvestigation and active search.

Table 20.15 . Botswana : results of vaccination scar surveys, by age grou p and district, January-March, 19730-5 years

6-14 years

>_ IS years

DistrictNumberexamined

% with scarNumberexamined

% with scarNumberexamined

% with scar

Central 2 731 77 17 748 86 8 370 86Kweneng 1 599 80 6 118 84 3 669 88Ngamlland 178 82 1 167 86 722 86South East 800 78 3 204 79 1 479 77Other 3 021 71 9 525 79 7 734 68

EstimatedDistrict

populationa 1971 1972 1973(1973)

CentralKwenengNgamllandNgwaketseSouth EastOther

234 82872 09353 87091 31054 047124 231

3100050

84954

6690

I S000120

Total 630 379 36 1 059 27

Number of vaccinations112 402 149(thousands)

994

Plate 20 .4 . The child in this Mazezuru family de-veloped smallpox on 7 November 1973 ; anotherpatient with the same source of infection, whobecame ill on 15 November, was the last known casein Botswana .

Active search continued, with specialattention to the Mazezuru . This sect wasestimated to comprise only 3500-5000persons, who lived in 9 closed or semi-closedcommunities in towns near the railway . Theywere traders who travelled frequently to visitrelatives and friends in South Africa andSouthern Rhodesia as well as in other areas ofBotswana. Fortunately, they were distinctivein that the women wore all-white clothingand the men were frequently bearded . Sostrongly did they object to vaccination that onone occasion in April a community of 100persons left by train when they learned that ateam was coming to vaccinate them. Exten-sive discussions with Mazezuru churchleaders led to a verbal agreement that theywould persuade their people to accept vac-cination . Later, it was learned that the leadershad privately advised the members of theirsect to refuse to cooperate .

From April to September, no cases weredetected, but in September another caseappeared at a hospital ; the patient was a non-


Mazezuru girl who lived in the Mazezuruquarter of a migrant settlement near a miningcomplex. Five weeks of intensive searchturned up 5 more cases, but from discussionswith people living in the area, it was suspectedthat at least 6-10 additional cases had oc-curred. The first patient had become ill inJune and the last on 14 September . Again,nearly 2 months elapsed, when, on 21 Novem-ber, yet another case was found in the miningcamp, and this in turn led to 2 more cases atthe camp and 3 cases in Gaborone, the last ofwhom had become ill on 15 November .

More stringent measures were required tointerrupt the tenuous but tenacious chain oftransmission among the Mazezuru . MostMazezuru were comparatively recentimmigrants to Botswana, having comemainly from Southern Rhodesia . To enterSouth Africa or Southern Rhodesia they wereobliged to be vaccinated and they acceptedthis as a necessity . Mandatory vaccination inBotswana was proposed to the President ofthe country. He concurred and informedMazezuru leaders that either their co-reli-gionists must accept vaccination or theywould be deported. They agreed to bevaccinated .

From 1974 onwards, both smallpox andBCG vaccinations were administered by thehealth facilities in substantial numbers, scarsurveys in 1974 revealing an overall level ofvaccinial immunity of 95% . The 4 surveil-lance teams continued to encourage andsupervise this activity and to search for cases .Many suspected cases were investigated andspecimens examined but none proved to besmallpox .

Information regarding the age and vac-cination status of cases is shown in Table20.16. Nearly half the cases occurred inindividuals aged between 5 and 14 years . Theoccurrence of 34% of cases among adults is

Table 20 .16. Botswana: number of reported casesof and deaths from smallpox, by agegroup and vaccination status, 1971-1972a

a Further details not available for 13 other cases reported duringthis period.

Age group(years)

Number ofcases (%)

Number withvaccination scar

Number ofdeaths

< I 17 (2) 0 11-4 195 (18) 3 15-14 505 (47) II 0

15 365 (34) 18 0

Total 1 082 32 2

high compared to the situation in mostcountries, but it is not unexpected consider-ing the low level of vaccinial immunity inBotswana. Cases in infants (0-12 months)were thought to have been underenumeratedbecause of the tendency of parents to hideyoung children with smallpox . Thirty-two ofthe cases (3%) were reported to have had avaccination scar, but some of these wereindividuals vaccinated late in the incubationperiod. Only 2 deaths are known to haveoccurred (a reflection of the mildness of thedisease) ; one of them was the child withtuberculosis, already mentioned, who wasreceiving steroid therapy and the other was a2-week-old infant .

ANGOLA

Angola (population in 1970, 5 .6 million)reported no case of smallpox after 1966 . It hadan extensive network of hospitals, healthcentres and rural dispensaries which offeredsmallpox vaccination . In addition, 300 "ruralagents" travelled through assigned areas ofthe countryside giving vaccinations . Separatemobile units, numbering 26 in all, dealt withleprosy, trypanosomiasis and tuberculosis ;they also administered smallpox vaccine.Freeze-dried vaccine obtained from Portugal,France or Switzerland had been used since themid-1960s. Because freeze-dried vaccine wasin use and the number vaccinated annuallyamounted to 30-60% of the population,vaccinial immunity was probably high . Until1959, when transmission appears to have beeninterrupted, variola minor was the prevalentstrain : among 1712 cases reported between1950 and 1959, there were only 23 deaths .Outbreaks due to smallpox imported fromZaire occurred in 1962 (23 cases), 1963 (50cases), 1964 (1 case) and 1966 (3 cases) . Eachwas investigated by epidemiologists fromLuanda, the capital, and confirmed by virusisolation at a laboratory there. The extensivenational programme of vaccination contin-ued until the end of 1974, a special campaignbeing conducted in 1971-1972 in areas adja-cent to Botswana ; no imported cases werediscovered after 1966 . Vaccination andsurveillance activities were sharply curtailedduring 1974-1975, when civil war erupted,but by then more than 2 years had elapsedsince the major outbreaks in Botswana andmore than 3 years since the last cases hadoccurred in Zaire.

20. SOUTHERN AFRICA

CONCLUSION

As had been expected in 1967, smallpox insouthern Africa was not a major problem, buttransmission continued far longer thanhad been anticipated. Constraints on officialcommunication between WHO and thehealth authorities in several of the countriesor areas unquestionably inhibited progress . Inmost instances, national health officials werecapable of investigating and containingoutbreaks, but they needed instruction andassistance to carry out the task in a propermanner. Because the incidence of smallpoxwas low, effective surveillance and contain-ment might have interrupted transmissionmuch earlier and the final epidemic in Bot-swana would not have occurred .Considering the extensive number of

health units and special vaccination cam-paigns in operation throughout southernAfrica, it is perhaps surprising that smallpoxwas not eliminated from this area long before1967. However, in many of the countries fewof the health units offered vaccination, evento people attending their clinics . Moreover,except in Angola and Mozambique, liquidvaccine was the only type of vaccine used, andwhen supervision was poor, as in Botswana,Malawi and Zambia, the vaccine was notproperly refrigerated and there werecomparatively few successful takes. Whenfreeze-dried vaccine became widely available,the numbers of cases of smallpox diminishedrapidly and transmission was soon inter-rupted, even though, with the exception ofAngola and Botswana, few outbreaks wereinvestigated or contained .

The concluding episode in southern Af-rica-namely, the reinfection of and exten-sive spread of smallpox in Botswana-wasregrettable and, in retrospect, avoidable . Re-establishment of endemic smallpox mighthave been averted if a programme in Bot-swana had been initiated a year or more earlier .That Botswana was at significant risk,however, had not been appreciated . Theprincipal endemic focus of smallpox in SouthAfrica was in the Transvaal, near the borderwith Botswana, but this was not made knownto WHO until after smallpox had becomeendemic in Botswana. For their part, theSouth African authorities had been littleconcerned with the mild variola minor thatwas present and rarely investigated orcontained the outbreaks that did occur .However, even as late as June 1971, when the

995

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first case was reported in Botswana, promptaction might have aborted the ensuing epi-demic. Unhappily, there was a delay of fully 9months before an effective programme began .By then, an intensive and more costly effortwas required to stop transmission . Botswana'sprogramme, once begun, was imaginativelyand competently executed-the best of any insouthern Africa .

The exceptionally mild form of variolaminor found in Botswana and South Africadid not constitute a problem of public health

significance ; had this form of smallpox pre-vailed throughout the world, a global eradica-tion programme would not have been war-ranted. It was clear, however, that unlesssmallpox as a disease, whatever its degree ofseverity, were eradicated, long-standingprogrammes of vaccination and the issuing ofvaccination certificates for travellers wouldcontinue to be required. The eradication ofvariola minor in Botswana and South Africawas as important to the global programme aswas the eradication of variola major .

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