Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.
Rift Valley fever virus seroprevalence among ruminants and
humans in northeast Kenya
Johanna Lindahl1,2, Ian Njeru3, Joan ...
Today’s talk
1. An introduction to vector-borne diseases and
Rift Valley fever
2. Our project
3. Conclusions
Livestock
WildlifeHumans
Ecosystem
LH
WL
WH
X
Disease transmission Spillover event
Ecosystem services – and disease emergence
Ecosystem service Importance Effect of decrease
Provisioning Economics, livelih...
WNV
WNV
Malaria
Malaria
Malaria
Dengue
Zika
Dengue
Dengue
Dengue
Yellow fever
Zika
Yellow fever
TBE
TBE
RSSE
Borrelia
Borr...
k= Probability that a vector feeding on an infected host gets infected
Pf = Probability that a vector survives from one me...
Rift Valley fever
• Bunyaviridae, phlebovirus
• High mortality, abortions in ruminants
• Haemorrhagic fever, encephalitis ...
Why irrigation?
• More and more range lands in Africa are being
converted to crop lands through irrigation to
alleviate fo...
Anthropogenic action:
Increased irrigation
Effect on ecosystem:
Creates more larval habitats
Vector consequence:
More infe...
Our project
• Rift Valley fever prevalence
– Humans
– Ruminants
• Land use changes
– Protected area vs. irrigated area
– P...
Hypothesis
• Irrigation in an arid and semi-
arid area increases the risk for
Rift Valley fever
• But other diseases can a...
Study area
•Tana River and Garissa
counties, northeastern Kenya
!.
!.
Bura
Hola
0 10 20 30 405
Kilometers
´
Legend
Settlements
Irriga...
Land use change
• Making changes in a highly diverse landscape
• Increased number of scavengers
• Increased numbers of mos...
• Cross-sectional
– Humans
– Ruminants
– Mosquitoes
– Wildlife
– Ticks
• Longitudinal
– Human febrile cases
– Livestock: s...
Prevalence in humans
21.12% 21.70%
27.16%
21.94%
0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
30.00%
irrigation pastoral riveri...
Prevalence in ruminants
Ruminants
Overall
seropositivity
25.59%
Young 12.31%
Adults 30.22%
Male 14.81%
Female 28.80%
RVF-only part of the problem
– Too many differentials: Malaria, RVF, Dengue, YF,
Brucella, Leptospira, Chikungunya, CCHF
–...
Unwillingness to pay for prevention
Mosquito
nets
Vaccines and routine
clinic visits for kids
Boiling or other
water treat...
The vicious cycle
Healthy
livestock,
more
production
Better
livelihoods,
healthier
people
Sick
livestock,
less income
Poor...
Impact of poor animal health
Herrero et al. (2013)
GHG per kg of animal protein produced
Conclusions
• Land use changes can affect disease occurrence
• Irrigation can sustain inter-epidemic transmission
• More p...
CGIAR Research Program on
Agriculture for Nutrition and Health
Thanks to:
The whole DDDAC team
All participants
Acknowledg...
The presentation has a Creative Commons licence. You are free to re-use or distribute this work, provided credit is given ...
Rift Valley fever virus seroprevalence among ruminants and humans in northeast Kenya
Upcoming SlideShare
Loading in …5
×

Rift Valley fever virus seroprevalence among ruminants and humans in northeast Kenya

127 views

Published on

Presentation by Johanna Lindahl, Ian Njeru, Joan Karanja, Delia Grace and Bernard Bett at the first joint conference of the Association of Institutions for Tropical Veterinary Medicine and the Society of Tropical Veterinary Medicine, Berlin, Germany, 4–8 September 2016.

Published in: Science
  • Be the first to comment

Rift Valley fever virus seroprevalence among ruminants and humans in northeast Kenya

  1. 1. Rift Valley fever virus seroprevalence among ruminants and humans in northeast Kenya Johanna Lindahl1,2, Ian Njeru3, Joan Karanja3, Delia Grace1, Bernard Bett1 1 International Livestock Research Institute, Nairobi, Kenya 2Swedish University of Agricultural Sciences, Uppsala, Sweden 3Ministry of Health, Nairobi, Kenya 1
  2. 2. Today’s talk 1. An introduction to vector-borne diseases and Rift Valley fever 2. Our project 3. Conclusions
  3. 3. Livestock WildlifeHumans Ecosystem LH WL WH X Disease transmission Spillover event
  4. 4. Ecosystem services – and disease emergence Ecosystem service Importance Effect of decrease Provisioning Economics, livelihoods Increased poverty Regulating Health, environment Increased disease Cultural Well-being, recreation Increased stress? Supporting Basis for the other services Increase in all above
  5. 5. WNV WNV Malaria Malaria Malaria Dengue Zika Dengue Dengue Dengue Yellow fever Zika Yellow fever TBE TBE RSSE Borrelia Borrelia RSSE JEV JEV MVE Ross River SLEV VEE, EEE, WEE VEE Bluetongue Bluetongue African horse sickness African swine fever African swine fever Chikungunya Chikungunya JEV Babesia Babesia Anaplasma, Chikungunya Zika Sleeping sickness Chaga’s disease RVF, WNV Chikungunya Climate and climate changes Globalization Urbanization Land use changes Why are vector-borne diseases emerging?
  6. 6. k= Probability that a vector feeding on an infected host gets infected Pf = Probability that a vector survives from one meal to the next Pe= Probability that a vector survives the extrinsic incubation period, EIP Q= Probability that a vector feeds from the right host – blood index for the host HBr= Host biting rate, the number of vectors feeding from an animal per day v= Probability of pathogens becoming infectious in the vector C= Vector capacity C= HBr Qvk Pe/(1- Pf) Vector capacity and competence
  7. 7. Rift Valley fever • Bunyaviridae, phlebovirus • High mortality, abortions in ruminants • Haemorrhagic fever, encephalitis in humans • Arbovirus – but also directly transmitted
  8. 8. Why irrigation? • More and more range lands in Africa are being converted to crop lands through irrigation to alleviate food insecurity • Results: major trade-offs in ecosystem services More food produced (provisioning services) at the expense of biodiversity and regulatory services (disease, flooding, erosion)
  9. 9. Anthropogenic action: Increased irrigation Effect on ecosystem: Creates more larval habitats Vector consequence: More infected vectors Epidemiologic consequence: More individuals exposed Increased disease Case study- irrigation and disease
  10. 10. Our project • Rift Valley fever prevalence – Humans – Ruminants • Land use changes – Protected area vs. irrigated area – Pastoralist areas
  11. 11. Hypothesis • Irrigation in an arid and semi- arid area increases the risk for Rift Valley fever • But other diseases can also be affected by this… • … and the doctors don’t know if it is Rift Valley fever Study site with stagnant water in irrigation canals – source of water for the locals but also breeding grounds for mosquitoes
  12. 12. Study area
  13. 13. •Tana River and Garissa counties, northeastern Kenya !. !. Bura Hola 0 10 20 30 405 Kilometers ´ Legend Settlements Irrigation Schemes permanent mixed temporary !. Towns Study Block Tana River County Tana River Other Rivers Riverrine Forests Study site
  14. 14. Land use change • Making changes in a highly diverse landscape • Increased number of scavengers • Increased numbers of mosquitoes
  15. 15. • Cross-sectional – Humans – Ruminants – Mosquitoes – Wildlife – Ticks • Longitudinal – Human febrile cases – Livestock: shoats – Mosquitoes Dynamic drivers of disease in Africa Case study: Kenya
  16. 16. Prevalence in humans 21.12% 21.70% 27.16% 21.94% 0.00% 5.00% 10.00% 15.00% 20.00% 25.00% 30.00% irrigation pastoral riverine Total Significantly higher prevalence in men
  17. 17. Prevalence in ruminants Ruminants Overall seropositivity 25.59% Young 12.31% Adults 30.22% Male 14.81% Female 28.80%
  18. 18. RVF-only part of the problem – Too many differentials: Malaria, RVF, Dengue, YF, Brucella, Leptospira, Chikungunya, CCHF – Socioeconomic consequences and factors
  19. 19. Unwillingness to pay for prevention Mosquito nets Vaccines and routine clinic visits for kids Boiling or other water treatment Insurance (annual fee) Other health prevention Mean 762 254 6.8 0.9 586 Range 0-3150 0-5000 4 households paid between 150-600 220 households paid nothing, one household paid 200 0-6000 How much did you spend last year on the following health protection (Kenyan shilling)? Deworming Vaccinations (to prevent not to treat) Tick and fly treatments Insurance (annual fee) Mean 928 437 599 0 Range 0-11000 0-5000 0-5000 Not existing How much did you spend last year on the following health prevention for animals?
  20. 20. The vicious cycle Healthy livestock, more production Better livelihoods, healthier people Sick livestock, less income Poorer people, more disease
  21. 21. Impact of poor animal health Herrero et al. (2013) GHG per kg of animal protein produced
  22. 22. Conclusions • Land use changes can affect disease occurrence • Irrigation can sustain inter-epidemic transmission • More people, more food insecurity and more disease
  23. 23. CGIAR Research Program on Agriculture for Nutrition and Health Thanks to: The whole DDDAC team All participants Acknowledgements
  24. 24. The presentation has a Creative Commons licence. You are free to re-use or distribute this work, provided credit is given to ILRI. better lives through livestock ilri.org

×