Tro11s. N1Jt/. Acad. Sci. & Tech., Philippines (2001) 23: 105-119

HELMlNTH ZOONOSES IN THE PHILIPPINES: PUBLIC HEAL TH PROBLEMS ASSOCIATED WITH EA TING

HABITS AND PRACTICES

ACADEMIClAN SALCEDO L. EDUARDO Professor and Dean

College of Veterinaty Medicine University of the Philippines Los Banos

College. Laguna 4031, Philippines

ABSTRACT

A number of helminth zoonoses have been recorded in the Philippines and majority or these is transmilled through the food. These include ~hinostomosis, artyfechinostomosis, hcterophydosis, camcopballosis, paragonimosis, opisthorahiosis, fasciolosis, taeniosis/cysticcrcosis, spirometros is/sparganosis. gnathostomosis, in1es1inal capi llariosis, angiostrongylosis and an isakiosis. The causative agents involved, animal hosts, human infections with these diseases and their distribution and transmission are discussed

Taenia saginata asiatica is recently recognized as the one of the two causes of human taeniosis in 1he Philippines. Previous reports locally of Taenia saginara were in fact of Taenia saginata asiatica. thus data for the former are now referable to the latter. The pig and its liver serve as the intermediate host and organ predilection site of the cysticcrcus (larval form), respectively for this species. Accordingly. meat inspection of slaughter pigs should now include the examination of the liver and not only of the muscles us currently practiced. The mudfish , Channa slriata (dalag) is recently recorded to harbor the larva of Gnathostoma doloresi. Human infection with the nematode may occur through ingestion of improperly cooked infected fish.

While some of these zoonotic diseases are now rarely observed, still others continue to be public health problems. Many are endemic in certain aren~ of the Philippines beeouse of the food habit of consuming raw or portly cooked fish, edible snails and crustaceans and meat in these areas.

More studies on the epidemiology and 1r.msmission, inc luding the animal hosts invo lved locally, arc still needed for some of 1hese problems. Changing the eating habits and prac11ces can prevent human infection with many of these diseases. Prllpcr disposal of fecal materials from both man and animals can olso help control or if not cut the life: cycle of many of these infectious agents. These however require aggressive health education campaign in order to be successful.

105

I 06 Salcedo L. Eduard<>

INTRODUCTION

In the Phjlippines, parasitic diseases still rank high as health problems in both man and animals. Biomedical surveys conducted among human populations in the country point to parasitic diseases as important public health problems (Cross & Basaca-Scvilla. 1984). These are aggravated by prohlems of poveny. malnutrition and a declining economy. Some of these parasitic problems are caused by helminths, which are transmissible from animals to man or vice versa. Human infec tion with some of them is a1.:quircd through the food. Ju t as the Philippines is composed of many islands, the inhabitants arc also varied with respect 10

customs, food habits and pmctices and many of these, as will be shown latter. favor the transmission ofbelminth infections.

Zoonoses, as defined by WHO (1979). are those diseases and infections which are naturally transrrutted between vertebrate animals nnd rmm. The species of animal parasites causing infection and shared by both man and other vertebrate animals are therefore classed as zoonoscs. This paper deals only with fchlcl-lmrnc zoonoses caused by helminth parasites (rrematodci., cestoucs. nematode · and acanthocephala).

The nomenclature of helminth disea:.:e:. given in this paper follows the Standardized Nomenclature of Parasitic Diseases (SNOPAD} as proposed by the World Association for the Advancement of Veterinary Parasnology (W /\A VP) (prepared by Kassai et al .. 1988).

Scientific names of fish host-; follow the currently rerngni7.cd narm:s given in the checklist of the parasites of fishes of the Philippines by Arthur and Lumanlan­Mayo (1997).

TREMATODE ZOONOSES

Echinostomosis

J luman echinostomosis in the Philippines is primarily caused by Ech111osroma iloca1111m. The adult nuke occurs in the small intestmes, thus the disease condition is also called intestinal echi nostomosis. IL is widespread with prevalenct: of 3~o but higher among llocanos in Northern Luzon where it reached to as high as 44"·o (Cross & Basaca-Scvilla, L 986)

Rattu:; spp. are important animal hosts. Dogs and c~us were clnimcd as may equally be important. No data howevi::r as yet arc availabl<.: on the prc,·alcncc of natural infection especially on the last two hosts. A variety of laboratory animals especially rats, mice and hamsters are the most susceptible experimental hosts (Yelasque7., and Eduardo. 1994).

This parasite requires fresh water snails as intcm1ediatc host to rnmplcte ns li fe cycle. Locally. the freshwater planorb1d snail. Gyraul11s plirc1sadi serves as the first intermediate host and the second imcm1ediatc hosts include a variety of freshwater snails including G. phrasadi and Pila conicv. Filipinos cat the lattt:r

Tra11sac1ions of the National Academy a/Science & Technnlogy Phi/ippine.r 107

species, thus it is considered the primary source of infection. The llocanos of northern Lu1,on are known to consume partly cooked Pila conica (locally called "bisukol") hence human infection is highest in this region (Eduardo, 1991 ).

Ar tyfechinostomosis

Artyfechi11os10111u111111alaya11um (syn.= Cathaemasia cnbrerai) is the cauce of this condition and it occurs in the intestines of the infected host. Thill species has already been reported for a long time in other Asian countries. Its occurrence in the Phil ippincs bas been recorded in man and the pig (V clasqucz and Eduardo, 1994 ).

Human infections with this species have been reported from lsabela and Tarlac province (Monzon & Kitikoon, 1989). Pigs from Pangasinan and Bulacan were found naturally infected at slaughter. A total of 1,205 worms \Vere recovered from one pig (Eduardo, 1989).

This hclminth species also requLres freshwater snails as intermediate hosls to complete its development. Tbc snails, Bullastru cu111i11gia11u. Radix t/uadmsi and Physastra /11mger.fordia11a are oaturally infected in the Philippines and therefore serve as the second intermediate host. The source of human infeclion howi.:ver is Bullastra cwni11giana as this is edible to some Filipinos. All humun c3ses in lsabclu had a hiswry of eating ra-w snail of this species that is locally known as "hirahid ··_ It is prepared by shaking the snail witb salt to remove mucus secretion. Then salt, ginger, onion, vinegar, pepper and other spices are added (Tangtrongchitr & Monz.on, l 99 1). B cumi11gia11a collected from two distant places namely. San Pablo, Laguna in Southern Luzon and Echague. Isabela in Northern Lu7.on were found naturally infected with metacerariae which when fed to rats and hamster yielded adults of _.f. 111alaya11u111 (Cabrera et al .. 1986. Monzon & Kitikoon. 1989).

Exact information on its epidemiology. transmission and its prevalence in pigs and man and other animals locally remains to be worked 0111.

Hctcrophyidosis

Members of the trematode family Heterophyidae arc th1.: cause~ or thi:. condition. In the Philippines, several species of the family have bccn recorded from carnivores and birds. Many of these species arc known to be transmissible to man (Velasquez and Eduardo, 1994). Only four species namely, flaplorc/1is taichui. H. y<>kogawai, Procerovum caldero11i and S1ella111lzdzus11111s /alca111s (=S. pse11docirrara) have actually been recorded in human infee!ionl> locally and 1hcsc were associated with lesions in tbe heart, brain and spinal cor<l. Unspccifie<l hcterophyid infections of man detected through fecal examination hnvc also been reported (Cross & Basaca-Sevillo. 1984).

There arc no data available yet on the prevalence of infection in animals. ln human. less than one percent of 3,000 stool samples cxamin~·d from various places in the country was found positive for ht!lerophyid ova (Cross & Bnsaca­Sevi Ila, 1984 ).

I 08 Salcedo l . Eduardo

Heterophyids require freshwater snails and fishes as first and second intermediate hosts, respectively to complete their cycle. A variety of food fi shes. both freshwater and marine have been found infected with the metacercariac of heterophyid species (Velasquez and Eduardo, 1994) and those harboring the metacercariae of the four species mentioned above are given in Table I. Infection therefore occurs through ingestion of raw or partly cooked fish contai ning metacercaria. The life cycle of only two species, H. taichui and P. calderoni are known in the Philippines. The snail hosts are Melania juncea and 711iara rique11i, respectively (Velasquez and Eduardo 1994).

Table L Philippine fishes found harboring metacercariae of heterophyid species.

Fish species:

Scientific name (local name)

Acentrogobius jonthi11opterus (biyang sapa)

Ambassis buruensis (lni'lgaray)

Anabas tes111dineus (martiniko)

Arius manillensis (Manila k.anduli)

Heterophyid Fish species:

species* Scientific name (local name)

PC Liza subviridis (baonk) (=Mugil d11ss11mieri (tali long)

HY, PC Mugil sp. (banak)

PC.SF Oreochromis niloticus (tilapia)

HY Pe/ates quadrilineatus (agaak)

Hctcrophyid

species*

HT, HY , PC.Sr

HY. PC.SF

HT

HYJ'C, SF

Atherina balabacensis PC Plarycephalus indicus PC (guno) (sunog)

Butis amboinensis (biyang sunog) PC Poecilia latipinna (bubunlis) PC

Channa striata (dalag} HT.HY. PC Ptmtius binotat11s (pait) HT

Chanos chanos (bangus) .PC Rhynchorhamplws georgii (buging) HY, PC

Clarias batraclrus (hi to)

Eleutheronema tetradactylum (mama Ii)

Epinephelus corallicola (lapu-lapu)

Gerres filame11tos11s (malakapas)

Gerres kappas (mulakapas)

Glnssngobills gi11ris (biya)

"Legend l/aplorchis 1aichu1 - HT Prucao••um cnltleroni - PC

HY

PC

HT, PC

PC

HY

PC

Scarophagus argus (kitang) PC

Siga11us ca11aliculat11s HY.PC (barangan)

Siga11us gutatus HT, HY {barangan)

Siga1111s javus (barangun) HY. PC

Spratellicyprfs palata (manobud)

llT

Teraponjarbua (bagaong) HT. liY.Sf

Haplordnr >YJkogawai HY S1<1/lm11clta.f11111sfa/ra11" - SF

Transactions of the National Academy of Science & Technology Philippines I 09

Carneophallosis

Carneophallus brevicaeca is the etiologic agent o f this disease condition. In the Philippines, it has been reported in man associated with lesions in the heart and spinal cord; in the bird (Sterno a/bifrons sine11Sis) and the fish ( G/ossogobius giuris). The shrimp, Macrobrachium sp. has been found to harbor metacercariae thus serving as intennediate host for the parasite (Velasquez. 1975; Velasquez and Eduardo, 1994). i nfect ion occurs through ingestion of raw or partly cooked shrimps. Other invertebrate intermediate and animal definitive hosts still remain to be known.

Paragonimosis

Members o f the genus Paragonimus are the causes of this condition. Tn the Philippines, Miyazalci ( 198 1) concluded, after a taxonomic study on the lung flu kes, that Paragonimus westermanifilipimis is the only species and is respons ible for this condition in the country.

Paragonimus infection is endemic in certain areas in the Philippines. Reported human cases were mostly from Sorsogon, Samar and Leyte. Prevalence in endemic areas may reach 4.6-12.5% (Cabrera & Fevidal, 1974). Wild rats (Rat/us 11orvegicus) may play an important role in maintaining the cycle in nature and the prevalence in these animals may reach 9.4-11.1 %. (Cabrera. 1977).

This species requires freshwater snails and crabs as first and second intennediate hosts. respectively to complete its cycle. Wild boars may serve as paratenic host. Jn the Philippines. the snail Brotea asperata and the mountain crab. Sundathelphusa philippina serve as intennediate hosts (Velasquez and Eduardo. 1994). Human infection results from consumption of infected crabs, raw or pnnly cooked.

In Sorsogon, Lcytc and Samar. where paragonirnosis is indemic. inhabitants are known to consume the crab host raw. A preparation of fresh crab juice known as "ki11nga11g ·• is considered a local delicacy. Cabrera & Fevidal ( 1974) noted that inft:ction is more frequent in males than in females but this difference was attributed to certain customs and habits rather than sex. Males in these areas were observed to eat crabs raw during drinking sessions with the local wine ("hast") especially during festivi ties.

Opisthorcbiosis

Opisthorcltis (=Clonorchis) sinensis, the etio logic agent o f this condition, has been reported in man in the Philippines during routine stool examination . Jn a survey of 30.000 Filipinos by Cross & Basaca-Sevilla ( 1984), ova similar to that of Opistltorchis si11e11sis were detected in I 35 stool samples.

IL is a known fact that this parasite requires snails and a variety of freshwa ter fishes serve as intermediate hosts but the species involved in the Philippines are

11 O Sa/ca.Jo L. Ed11a1·do

not yet known. Likewise. data on unimal host infection especially carnivores arc still needed.

Fasciolosis

Two species, Fasc:iola giga111ica and F hepatica have been reported in animals in the Philippines but recent investigations based on previous and current collections have shown that the fonner is the predominant if not the only species now occurring. in this country (Velasquez and Eduardo, 1994 ). The prevalence of Fasciola infection in domestic rnminants is high. In endemic areas, it may reach to as high as 95%. Control program instituted on a nationwide scale in 1979-1981 reduced the infection rate in some areus. Lamcm & Mnnucl ( 1981) found a prevalence of 3.6% in cattle and 38% in water bu ff aloes ( carabaos). The snail intermediate hosts in this country are l y11111aea philippinensis and l . a11ric11laria rubiginosa, which arc likewise distributed throughout lhc islands. Animals become infected through the Ingestion of metacercanoc contmncd c1n grasses and other water plants or drinking contaminated water.

Only two cases of human infection with Fascio/a have been recorded in the Philippines (Eduardo, 199 1 ). The exact origin of the infection could not be traced but probably as a result of ingestion of partly cooked lpomea ("kangkong") or accidental ingestion of wuter plants harboring mctacerc:ariae of the fluke. The high prevalence in animals in endemic areas put the local human population at risk 10

infection.

CESTODE ZO ONOSES

Taenlosis/Cysticercosis

Taenia solium and T. saginata asiafic:a are the causes of human tacniosis in the Philippines. What was previously referred to in literature as Taenia saginata or Taenia saginata-Like in Taiwan, Korea, China, Thailand, Indonesia and the Philippines is in fact Taenia saginata asiatica (Fan & Chung, 1998). The true Taenia saginata requires cattle and water bufalloes as intermediate host and its cysticerci are found in the muscles. Ta e11ia saginaw asiatica on the other hand requires pig as the intermediate host and its cysticerci occur in the liver. Infection of a pig with ova of Tae11ia saginata asiatica recovered from an infected woman in Leyte revealed the occurrence of cysticerci in the liver (Pejana & Eduardo. 2000). This suggests that examination of slaughter pigs at meat inspection should include the liver and not only the muscles as is currently practiced.

Various surveys showed Taenia prevalence of less tJ1an one percent (Arambulo et al., 1976; Cross & Basaca-Sevilla, 1983; Camey et al.. 1987). Between the two species, T. saginata asiatica is more common. According to Arambulo et al. ( 1976). out of 1,000 cases of parasitologic condition examined annually at the Philippine General Hospital , an average case every two years of

Trw1s11c1iuns u/ 1/le Natirmul Academy of Sdf!flt'c: & Teclinology PhilippznL'S 111

one T. solium and six T. saginata asiatica were recorded. In T. sagi11ma asiatica endemic foci in Leyte. Cabrera ( 1973) reported a prevalence of I 0.26% for this species.

Human cases of cysticercosis bave been reported in the Philippines and were diagnosed as either that of T. solium or highly suggcsti\"e of this species (Qu1mosing et al .. 1984: Eduardo, 199 J ).

In animals, cysticcrcosis is more common in swine than either In canJe or water buffalo and the prevalence in slaughter an1maJs arc :: swine 1.67%. cattle 0.02% and water buffalo 0.03%. Human infection results from consumption of raw or improperly cooked infected pork and beef.

Spiromctrosis and Sparganosis

Spiromelra species and their spargana have been reported in animals in the Philippines. Sparganum is widespread in tadpoles and frogs and has been found in a bird. l:wbrychus ci11namum11us. a lizard, Gecko gecko and several species of snakes namely, lapemis hardwickii, Boiga dendrophila. Ahaerulla ahaetulla. A. caudoli11eata and Natrix cluysarga (Velasquez and Eduardo. 1994).

AduJt D. la1um has been reported locally from a boy that d ied of anemia. Since D. /atum is only found in temperate countries of the Northern Hem isphere, this identification is doubtful. It is possible that the species in question is Diphyllobothrium erinaceieuropaei (=Spirometra eri11acea. S. mansonoides) (Velasquez and Eduardo, 1994). Stool survey showed diphyllobothrid ova in less than one percent of 30,000 persons examined in various places in the Philipp ines (Cross & Basaca-Sevilla, 1984).

Up to 1962, four human cases of sparganosis have been reponed locally and since then no other case has been reported. As all cases gave no history o f having eaten fresh meat o f frogs, reptiles and birds nor used them as poultices. the mode of transmission was attributed to the drinking water with infected cyclops (Jueco, 1982).

NEMA TOOE ZOONOSES

Gnathostomosis

Members of the genus Gnathostoma cause this condition. The genus is represented in the Philippines by three species namely, G. spinigerum, C. liispidum and G. doloresi. Gnathosloma doloresi was first discovered and reported as a new species in the Philippines by Tubangui ( 1925) from the stomach o f a pig in Los Banos, Laguna. It has been subsequently reported in the same host locally (Velasquez and Eduardo, 1994) and in several Asian countries and some Pacific Islands (Daengsvang, 1982). All three species have been recorded in man in other Asian countries but onJy G. spinigerum has been reported in man locally.

11 2 Salcedo l . Eduardo

Gnatho.ftoma spp. in order to complete their development requires aquatic copepods and fishes as intermediate hosts and a wide range of paraten ic hosts muy iotcr\'enc as "extension host" in the cycle.

G. spinigerum has been reporced locally in dogs, cats. flying lemur and palm civet. Copepods, Cyclops (£11cylop.'>) .<rerru/a111s and C (Mi<:rucydupsJ hic:ulor and freshwater fishes namely, G/ossogohi11s giurus. Opltic.:epltalm striatus and Therapon argent1.>us serve as first and second intennediatc hosts, respectively. The water snake. Hurria rynclrops and the frog. Rana limnoclwris may serve as the local paratcnic hosts as they were found to harbor larvae of thi:; parasite). Only three cases of human gnalhostomosis have been reported locally and thcsl! were attributed to G. spinigerum (Velasquez and Eduardo, J 994 ).

Both G. hispidum and G. dolorcsi have been recorded in pigs in the Philippim:s (Velasquez and Eduardo. 1994 ). There is no case as yet reported of human infect.ion with G. hispid11m and G. doloresi in the Philippines. However, cases of human gnuthostomosis have been reported in China, Japan and Thailand due to these two species. Gnatlwstoma doloresi is currently recog11i:1ed as an important cause of clinical human gnathostomosis in Japan (Akahanc ttl di .. 1982: Ogata el ul., 1988; Nawa et al .. 1989).

Cases of human gnathostomosb; due to G. hispidum in Japan have been attribured to the com•umption of raw loaches (Misgurnus cmgillicaudutus) usually imported from Mainland China. Taiwan u11d Korea. It is interesting to note here that the lish host (Misgurnus ang11illi<.:awlatus). which is the source of human infection with this -:pecics in Japan, now abounds in the rice terraces of Ifugao. The I fugao call it "jojo" which probably is derived from the Jafl'JJlesc name "<lojo" for the fi sh. How the fish found its way to the Cordillera i:; not exa;:tly known. It is postlllated that it was broughl by Japanese i.-oJJiers during Wl'rh.I War ll as a protein supplement for their tlie1 ( Balatan. J 993). This is a ~asc of lhe introduction of a new su itable intermediate host for a parasite already existing in a country. The introduction increase-; the nmg~ of suitahle intennediatc host a\'ailable locally and hence insuring further diss<."mination and continued survival o f' the pua~ite

concerned. In Japan, wild boars. salamanders. frogs and snake~ have been reported to

hurbor larvae of G. dnloresi (lmei d al .. 11)8t); Miyazaki & Ishii. 195:!; Has1.:gawa et al., 1982). Human infections with G. cloloresi in Japan have been attributed to the ingestion of raw rncat of these hosts.

The author et al. (2001, in press) h.as found larvae of G. dolores i in sorne Ophic:cphal11s srriatus ("dalag") examined from Laguna Lake suggesting that this fish serves as the inrcrmcdiatt· host locally. Human infection ruay result from consumption of improperly l'OOkcd infected !ish,

Intestinal Capillariosis intestinal capillariosis of man is caused by Cupillarici philippimmsis. ·n1e species was firs< discovered and described as a new species by Chitwnod c:t nl. ( 1968)

Tra11.ractlons <>flhe National A'·"demy a/Science & Tedinaloxy l'ltilippitws 1 IJ

based on specimens recovered from an llocano patient in the Philippines that died of the infection. Subsequently, the parasite has been recorded in Japan, Thailand, Taiwan, Korea, India, Iran and Egypt.

111 the Philippines, intestinal capillariosis is endemic in coastal areas of ~orthern Luzon in the province of flocos Norte, Cagayan, lsabela, !locos Sur. La Union, Pangasinan and Zambales. Cases have also been reported in Southern Lcyu:), Bohol/Misamis Oriental and Agusan del :'forte in Northeastern Mindanao. Since 1967, over 2,000 human cases have been documented (Cross & Basaca­Sev1Jla, 1984).

The cycle of C. philippinensis in nature has not been fully detcnnincd,. Experimental evidences however point to rresh and brackishwater fishes as the sources of infection (Cross & Bhaibulaya. 1983). Human infection may result from consumption of raw fish infected with larvae. Hypseleotris bipartifa has been found to be a natural source of infection in ll l)COS Sur (Cross & Rasaca­Sevilla, 1991 ). Dcvdopment of the parasite to the infected lurva ha!' been demonstrated experimentally in fishes (Hypseleolris biµartita or ' 'bagsit"; Cho11ophorus mela11ocepha!t1s or "bukto, biyang bato"; Amba.uis miops or "bagsang"; Eleotris melanosmna or "bi.mt"; Sicyopterus sp . or " ipon" and Poecilfo reticulaw or "guppy") found in endemic areas in Northern Lu:r.on . With the exception of Poecilia reticulata, the rest are often eaten uncooked and gravid llypseleotris bipcmica is especially reli::;hed in the raw form (Cross & Basaca­Se,·illa, 1991 ). Residents of cndcmi,; areas in Northeastern Mindanao were also noted to consume raw fish (Camey e1 al .. 1987).

Fish-eating birds arc imponant reservoir host and responsible in disseminating infection along their migratory path. Experimental studies showed susceptibih~y of some birds to infection with the parasite. Tn the Philippines, a b ird. fxobrychus sp. (bittem) has been found to ltarbor a male specimen of the parasite. Other species of fi sh may be more commonly infeckd. Autoinfection is a part of the cycle in mammals as evidenced by embryonated ova produced by female worms. Human infection of C. philippmensfs still occurs in the Philippines but at a very low rate (Cross & Basaca-Sevilla, 1991 ).

Angiostrongylosis

Angiostrongylus ,;a111011ensis is tht' only species of the genus reported in the Philippines. This specks occurs as adults in. the lungs of rats and se\'eral species (If rats have been found naturally infoc1ed with the parasite with inr.idencc ranging 3- 10% (Cross, 1982). About 29% of field rats (Rattus m. mindanrmsis) examined from M!lyorga, Lcyte were found naturally infetted with this lungworm (unpubli1'hed).

Land snails. Ac:hatina fulic:a. Hemiplecta sagilliferu, Hdicostyla muc:rostonza. Chloreu fibula and Cyclophorus sp.; garden slugs, !merino plebeia and Laevicaulus alte wen~ found harboring larvae of the parasite (Cross, 1982). Velasquez (t 972) found 100% of Achatina fulica and Vcro11icclla :.p .. and 50% of Pila l1t=onic11

114 Salcedo l . Eduardo

infected with tbe larvae of A. cantonensis. Prawn, fishes, crabs, can le and chicken have also been shown to serve as paratenic hosts (Velasquez, 1981 ).

Aogiostrongylosis in human affects the central nervous system where the migrating larvae cause a condition called tropical eosinophilic meningitis. Human infection results from ingestion of paratenic hosts and raw vegetables contaminated with larvae from infected mollusks. Ten human cases, all non-fatal. presumably due to larvae of A. cantonensis have been reported locally (Cross. 1982).

Aoisakiosis

This condition is caused by tbe larval stages of anisakine nematodes persisting in the alimentary canal or penetrating the tissues of human after consuming raw or semi-raw fish. A variety of fish species acts as intem1ediate/transport hosts fo r the larva which mature to aduJt in warm blooded marine mammals.

Human cases of anisakiosis have been reported in the Americas. Europe and Japan resulting from ingestion of raw or semi-raw fish (WHO, 1979). While no human case has been reported as yet in the Philippines. a wide range of fish species have been found to harbor anisakine larvae (see Table 2) (Velasquez. and Eduardo, 1994). The potential of human infection in the Philippines therefore is great especially now that many Japanese food preparations of raw and semi-raw fish (sashimi, etc.) are now gaining acceptance among Filipinos. It is also possible that there were human cases of anjsakiosis in the Philippines but were unrt:ported either because of the difficulty of its recognition or many local physicians are still unaware of this condition or both.

Table 2. Philippines fishes found harboring anisakine larva (from various authors)

Scientific name (Local Name)

Alec/is sp. (pampanog pull) Acunthopagn1s berda (bakoko) Amblyguster sirm (tonsoy) Apogon ellioti (dangat) Carangoides armatus (lawuynn) Cara11x sp. (talakitok) Caesio lunaris (dalagang bukid) Decaptcrus sp. (galonggong) Eleutlrerom:ma telradactylum (marnali) Epi11ephelus sp. (lapu-lapu) Euthynn11s affinis (katsarita) Gerres jilamento:ms (malakapas) lacrarius lactarius (pagapa) leiog11atlius equulris ( lawayakan) leiognathus sp. (sapsap, tambong) Lutjanus malabaricus (maya-maya)

Scientific Name (Local name)

0.":Q,11rictltys micrulepis (talimu~uk) Pe1111alria aenea (alakaak) Pinjalo pinjalo (sulid) Poecilia latipit111(1 (bubuntis) Priaca111lrus ta yen us (bisugong tsina) Pse11odes erumei (dapa) Rastrelliger brachysoma (ulumahun) Rastre/liger kanagurta (alumahan) Sartlinella ln11gicep.1· (tamban) Sardine/la abella (bagnsbas) Suurida tumbil (kalaso) Scatoplwgus c1rg11s (kitang) Scomberomorus co111111erso11 (tanguiguc) Sl.'!ar cru111enopJ111ta/11111s (ma1ang-baka) Selaruic/es leptolepis (salay-salay) Splryraena langsar ( turi;ilyo)

Tra11sac1ions of the Nauo11al Academy o/Scie11cr & Tcchnu/<Jgy fh1/ippi11e,t 11 S

Table 2 (continued)

Scientific name (Local Name)

l 111janus villa (dayang-day11ng) Megalaspis cordyla (orilcs) Mene muculata (hiwas) Murae11csox ci11ereus (pindanga) Nemipreru:i sp. (bisugo) Oro/it hes ruber (alakaak)

Scientific Name (Local name)

Srolephorus sp. (di lls) Sy11ap1111·a sorsoguncns1s (dapa) Siga11us sp. (samara() Teruprm jarhuu (bagaong) Trichiurus lepwrus (cspatla)

EATlNG HABITS AND PRACTICES, TRANSM ISSION AND PREVENTION

Ir is evident from the above of the role-played by food h:ibits and practice::. in tl1e epidemiology of these food-borne helminth zoonoses.

Food dishes prepared as raw or partly cooked are rel ished in some areas in rhe Philippines. "Kilawen'', is a term given to any preparation of raw meat, fi sh. snail, shrimp or crab, etc. usually with salt, vinegar and sometimes spices. This kind of preparation is considered a delicacy by some especially the llocanos of Northern Luzon. Thus human cases of echinostomosis, arryfechinostomosis. and intestinal capillariosis have been mainly from this pan of 1he country. In lsabela where human cases of artyfechinostomosis have been reported. the snail second intermediate host is eaten raw or partly fennented. lt is prepared by shaking the snail with sail 10 remove mucus secretion, then salt, ginger, onion. vinegar. pepper and other species are added (Cabrera et al.. 1986: Tangtrangchitr & Monzon, 199 1) and eaten or left ovemjght to ferment before being consumed. This in contrast to another place, San Pablo. Laguna in Southern Luzon. where the same snail has been found to have even higher percentage of infection than in lsabela. but no case of human infection has occurred as this particular snail is not ea1en. It is detested due to its slimy texture (Monzon & Kitikoon, 1989) ond even the local term, ''susong linta" meaning leechy snail sounds unpleasant to the car. ''Kilawen" is also popular among fo lks in Leyte. Pig li ver is cut into thin slices. soaked in vinegar with salt and condiments and eaten raw (Pejana and Eduardo, 2000). Pig meat, partly cooked and prepared as above, is also eaten hulf-cooked. Cysticcrcus (larva) of Taenia solium and T. saginata asiotica arc found in the muscle and li ver respectively of pigs, which serve as intennediate hosts. Human infection occurs through consumption of raw of partly cooked infected organs.

Pila conica (''kuhol", "bisukol") and Sundathelpusa philippina ("talangka"). the intermediate hosts of E. ilocanum and P. westermanifllipinus respectively, are eaten practically all over the country. However. echinos1omosis and paragonimosis arc prevalent or endemic only in certain areas. It is among the Jlocanos in Northern Luzon where echinostomosis has Lhe highest prevalence as the snail host

11 6 Salcedo l . Eduardo

is eaten sometimes raw or partly cooked. Similarly, paragonimosis is endemic in Sorsogon, Leyte and Samar wberc inhabitants are known to consume the crab host raw. A preparation of fresh crab juice known as "kinagang" is considered a locaJ delicacy. Males in these areas were observed to eat crabs raw during drinking sessions with the local wine ("basi.') especially during festivities. The same is true for intestinal capillariosis in Northern Luzon. The fi sh host. Hypseleotris bipartita is espi!cially desired when gravid (filled with eggs) and the entire fish is eaten raw. Another fi sh host. Ambassis miops in the raw fom1 1s bit1cn at the belly by some to suck out the juice (Cross & Basaca-Sevilla, 199 1 ). Residents of endemic areas in Northeastern Mindanao likewise were also noted to consume fi sh raw (Carney et al .. 1987).

Some human infections with these diseases may have passed unnoticed or may have been misdiagnosed as some are difficult to detect or lhc physician may not be aware of them.

Simply giving up the habit of eating raw food of animal origin could prcvl!nt human infection with a number of these zoonoscs. However. as the saying goc~. old habits may not easily be given up. Cross & Bhaibulaya ( 1983) also pointcu out that. it would be difficult in practice as some people in these areas, though properly informed about th.is transmission, still value their food hahits and mainta in that ''cooking destroys the flavor they relish as well as the llUtriti\'e \'3I UC of' the food". Nevertheless. with a more aggressi,·e health education campaign together with programs directed to the improvement of Uie living condition of the inhabitants in these areas, preventive measures against many of these zoonotic diseases could be achie\'cd ucccs fully (Eduardo, 1991)

HELMISTH PARASITES AS INDICATOR OF FECAL POLLUTIO~ OF THE ENVrRONM ENT AL

Pollution of the environment can ha\'e an important influence on the existence and survival of pa111:.1tes (WHO. 1979). Many of the hdminth agent!> can!>ing zoonoscs described in this paper are as:.ociated with fecal pollution nr the environment. whether land or aquatic. These parasite:. require intcrmeuiatc h<>Sts to complete their .;ydc. fn order to reach the intcrn1edia1c ho~I. a stage of the parasite has to lcuve the definitive or fi nal host and that srage, in almost all c~1se::.. ts the egg. The egg of the pani~itc is passed out with the feces of the uelinitivc host to the environment and from there to the intermediate ho!'t.

The presence of the larval stagt:S of the zoonotic agent in the cnvironmcni and in the intermediate host therefore indicates fecal contaminution from inl'cctcd definitive bosc~ . The zoonotic helminth agents reach their re~pcc:tivc intermediate hosr only after their eggs arc passed out with rhe feces of the ucfi111t1\'c host. Thus £. 1locu1111111. ti. 111ala.l'an11111, Fasci<Jla spp., Hi:templiyid spp., C. lm!1•1cae<:a. Cap1//arw philippi111!11sfa reach their mtcnned1atc boslS through fecal wmamina11011 of the water enqronment. Tae11ia spp. reach thcir intcnncd1atc ho~ts through fecal

Transactions of the National Academy of Science & TPchnology Philippines 11 7

contamination of the pasture or direct access of the intermediate host (pig) to fecal matter of infected definitive host (man). Proper disposal of fecal material whether of man or animal therefore is everyone's concern.

The presence of reservoir hosts also maintains the infection in a particular area. It was observed by Monzon & Kitikoon (1989) that Bullasrra cummingiana in Sampaloc Lake in San Pablo City had higher prevalence of infection with A. ma/aya1111m than the snails of the same species in lsabela. The cycle is probably maintained in the area by pigs and field rats as these are also known as definitive host of the parasite. It should be noted that piggeries abound around Sampaloc Lake and their excreta are allowed to pollute the lake. While there are no human cases of infection as yet, the presence of the parasite in the area still pose a threat to human health.

CONCLUDING STATEMENT

The Philippines has still a fast growing human popuJation at 2% growth annually. The current population is 75.6 million (Asiaweek, May 200 1). Food animal production has not kept pace with the demand of the increasing human population. Recent statistics reveal a slow growth for food animal production. A large proportion of the human population live in the rural areas and a much larger proportion of the food animal population is raised in backyards or small farmer bolder system as compared to the number raised in large commercial farms. This ecological profile of human and animal population distribution makes a large proportion of both populations put at risk.

It is also evident that these diseases are prevalent in rural areas where the population depends on agricuJture, fishery and forestry for livelihood. One-third of all goods and services produced by the economy is accounted to the agricultural/ rural sector, which also employs half of the country's workers and earns 36% of the country's export income (Department of Agriculture, l 989). "It can be said that unh~lthy working population can only mean low or reduced productivity and unwholesome meat such as in cases offasciolosis and cysticercosis can only lead to further reduction due to carcass condemnation of what is aJready an insufficient meat supply. Jn a country where poverty is widespread in rural areas like the Philippines, these diseases can only worsen what is already a bad situation "(Eduardo, 1991).

ACKNOWLEDGEMENT

This paper is a revised, modified and updated version of a lecture delivered by the author as a recipient of a SEARCA professorial chair grant al UPLB. I am grateful to SEARCA and the university for the grant.

1111 Sah·edo l. Eduardo

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