RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf ·...
Transcript of RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf ·...
![Page 1: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/1.jpg)
RIFT VALLEY FEVER IN RIFT VALLEY FEVER IN
SWAZILANDSWAZILAND
A REPORT OF THE 2008 SUSPECTED
OUTBREAK
Dr Patrick DlaminiVeterinary Epidemiologist
Department of Veterinary and Livestock Services
Swaziland
![Page 2: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/2.jpg)
What is Rift Valley Fever?What is Rift Valley Fever?
• First described in 1930 in the Rift Valley of
Kenya
• Caused by a virus (Genus Phlebovirus)
• Signs - high abortion rates in ruminants
(cattle, sheep, goats) and high mortality in
young.young.
• Transmission in animals: blood sucking
mosquitoes of many genera [Aedes
(resevoir), Anopheles, Culex, and others]
• Direct transmission to humans-handling
infected animals and meat
![Page 3: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/3.jpg)
RVF in South Africa 2008
![Page 4: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/4.jpg)
LegislationLegislation
• RVF is a specified disease according to the Stock Diseases Regulations (under section 3 of the Act).
• Minister may make disease regulations • Minister may make disease regulations as may be necessary to prevent the introduction or spread of diseases amongst livestock and other animals.
![Page 5: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/5.jpg)
LegislationLegislation
• Some of the main provisions of the regulations are:
– Outbreak notification,
– Movement restriction incl. imports/exports
of animals and their products,of animals and their products,
– Inspection of stock,
– Infection control procedures (detention,
isolation, testing, inoculation, etc),
![Page 6: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/6.jpg)
LegislationLegislation
– Slaughter of stock (+ or - compensation),
– Restriction and prohibition of animal
slaughter, Slaughter of stock (+ or -
compensation),
– Restriction and prohibition of animal
slaughter,slaughter,
– Control of slaughter places,
– Carcase disposal procedure,
– Etc.
![Page 7: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/7.jpg)
Swaziland
![Page 8: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/8.jpg)
Malkerns caseMalkerns case
• Dairy farm of 170 animals
• Farmer had experienced 6 abortions (start
dates 1st or 2nd wk of June 2008)
• Farmer advised to vaccinate herd – external
advice during simultaneous outbreak in SA
• 170 animals were vaccinated (live or killed
vaccine ??)
• Abortions continued –were investigated by
the dept –RVF was suspected.
![Page 9: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/9.jpg)
Malkerns case contMalkerns case cont
• Submitted 2 aborted fetuses at CVL for PM and virus detection.
• PM findings RVF suggestive
• Liver samples were RT-PCR +ve for presence of RNA to RVFV.presence of RNA to RVFV.
• Liver Immunoperoxidase staining +ve for RVFV antigen
• Concluded as possible outbreak and reported to OIE on 28/07/08
![Page 10: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/10.jpg)
Malkerns case contMalkerns case cont
• At time of immediate notification report source and vaccine used was unknown.
• On 05/08/08 follow-up report to OIE submitted with the following information.submitted with the following information.
• New information was that inactivated vaccine had been used on aborted animals.
![Page 11: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/11.jpg)
Immediate action Immediate action -- Malkerns Malkerns
outbreak?outbreak?
• A 10 to 15 km quarantine area declared around farm
• Area geographically defined by Great Usuthu river in south, Mdonjane area in Usuthu river in south, Mdonjane area in west, Mhlambanyatsi river on north, and Nokwane hills on east.
![Page 12: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/12.jpg)
![Page 13: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/13.jpg)
Tshaneni findingsTshaneni findings
• IYSIS farm advised to vaccinate following SA outbreak
• Low calving and weaning % problems
• Vaccinated March 08 using live vaccine• Vaccinated March 08 using live vaccine
• Tested 4 (unvaccinated?) animals where1 reacted strong +ve
• Tested 30 more animals (vaccinates and nonvaccinates)
• 2 out of 23 non vaccinates were weak +ve
![Page 14: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/14.jpg)
Tshaneni findings contTshaneni findings cont
• 3 out of 7 vaccinates weakly +ve
• No evidence of clinical disease in farm
• Logical conclusion at that time:
– IYSIS is free of RVF natural infection
– Serological reactors were probably all
vaccinated
– Possibility of live vaccine virus passed from
one animal to another
![Page 15: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/15.jpg)
IYSIS Area
![Page 16: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/16.jpg)
Issues pertaining to vaccine useIssues pertaining to vaccine use
• In both cases farmers advised by external vets - Not informed of national herd health status
• Suspicion of the disease and subsequent decision to vaccinate not subsequent decision to vaccinate not reported to local vet authorities
• In one case external vet brought vaccine
• In other case a local supplier imported vaccine without proper authorisation
![Page 17: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/17.jpg)
Issues pertaining to vaccine use Issues pertaining to vaccine use
(cont)(cont)
• Serology tests not able to differentiate vaccinated from naturally infected animals
• Live RVF vaccine causes clinical • Live RVF vaccine causes clinical symptoms particularly abortions
• Live vaccine suspected to spread within herd by mosquitoes and biting flies
![Page 18: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/18.jpg)
Swaziland
![Page 19: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/19.jpg)
Questions that needed addressing Questions that needed addressing
• Does Swaziland have natural RVF infection or is it reaction to live vaccines?
• What is the source of infection?
• Is the main vector (Aedes) present and active in the affected areas at this time of year?
• Why is the outbreak subtle?• Why is the outbreak subtle?
• Extent of human infection in suspect outbreak areas?
• Investigations and analysis carried out with the assistance of and in collaboration with CDC-Kenya team
![Page 20: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/20.jpg)
Animal health responseAnimal health response
• Clinical surveillance (case search)
• Serological surveillance in outbreak area and suspicious farms/diptanks
• Strict quarantine measures in place
• Vaccination generally prohibited
• Although vaccination was an option in outbreak area, it was however decided against
![Page 21: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/21.jpg)
Public health responsePublic health response
• Planned studies to establish vector ecology
(Malaria unit)
• Establish exposure of people at risk
(serological survey)
• Public education (safe handling of food-milk, • Public education (safe handling of food-milk,
meat, etc )
• Rapid assessment of public health facilities
• Development of case management plan
• Laboratory testing plan
• Development of surveillance plan (humans)
![Page 22: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/22.jpg)
Facts about Swaziland outbreakFacts about Swaziland outbreak
• Despite some serological reactions in animals, RVF virus could not be isolated in all samples taken (courtesy of CDC-Kenya)Kenya)
• Disease showed a mild clinical picture
• High risk farm workers tested negative to both IgG and IgM (courtesy of CDC-Kenya)
• Suspicious farms all had vaccination history
![Page 23: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/23.jpg)
ConclusionConclusion
• There was no active RVF infection in Swaziland
• Quarantine lifted August 2009
• Subsequent and ongoing surveillance • Subsequent and ongoing surveillance have not revealed suspicious reports
• > 80% samples from abortion cases in ruminants +ve for Brucellosis (B.abortus)
![Page 24: RIFT VALLEY FEVER IN SWAZILAND - OIE Africarr-africa.oie.int/docspdf/en/2009/RVF/DLAMINI.pdf · RIFT VALLEY FEVER IN SWAZILAND A REPORT OF THE 2008 SUSPECTED ... ( B.abortus ) Acknowledgements](https://reader031.fdocuments.net/reader031/viewer/2022021914/5c81532f09d3f2f3348c389b/html5/thumbnails/24.jpg)
AcknowledgementsAcknowledgements
Swaziland would like to thank CDC-Kenya
for the assistance provided in investigating for the assistance provided in investigating
the suspected RVF outbreak