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Detection and Impact of BVDV in Wild Ruminants

Detection and Impact of BVDV in Wild Ruminants. Julia Ridpath NADC/ARS/USDA. Picture courtesy of Michigan Department of Natural Resources. Impact of BVDV in wild ruminants?. Do wild ruminant populations act as BVDV reservoirs? Is there transfer between domestic and free living ruminants?

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Detection and Impact of BVDV in Wild Ruminants

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  1. Detection and Impact of BVDV in Wild Ruminants Julia Ridpath NADC/ARS/USDA

  2. Picture courtesy of Michigan Department of Natural Resources

  3. Impact of BVDV in wild ruminants? • Do wild ruminant populations act as BVDV reservoirs? • Is there transfer between domestic and free living ruminants? • Do BVDV infections have a negative impact on wildlife populations?

  4. Does BVDV circulate in wild ruminant populations? • Two lines of evidence • Serology • Antelope (eland), African buffalo, Bison (European & American), Big horn sheep, camelids (llama, alpaca) Cervidae (roe deer, red deer, fallow deer, mule deer, white tailed deer, caribou), chamois, giraffe, pronghorn • Isolation of virus • Antelope (eland), Bison (European & American), Cervidae (roe deer, red deer, fallow deer, mule deer, white tailed deer)

  5. Prevalence based on serology

  6. Can wildlife act as reservoir for BVDV? • BVDV PI animals in wildlife populations? • prevalence? • Transmission between domestic and free living species? • Can it happen? • How efficient is transmission?

  7. Persistently infected wildlife Do they exist in the field?

  8. Persistently infected wildlife Can they be generated experimentally? • Passler et al., 2007 - inoculation • Duncan et al., 2008 - inoculation • Ridpath et al., 2008 - inoculation • Passler et al., 2008 - exposure to PI cattle

  9. Are PI deer a source of infection for cattle? • How many PI deer are out there? • Survival rates • Limited size of herd may limit spread between deer • Confounded by feeding by humans

  10. Picture courtesy of Michigan Department of Natural Resources

  11. Transmission? • Can it occur? • How frequently does it occur? • Predominantly cattle to wildlife? • How efficient is transmission? • Does the virus change with transmission?

  12. Experimental Transmission • PI cattle to deer - Passler et al., 2008 • PI deer to deer - Passler et al • Acutely infected deer to cattle - Ridpath et al.

  13. Transmission following acute infection of deer • 3 fawns tested free of BVDV and antibodies against BVDV and 3 calves tested free of BVDV and antibodies against BVDV • Fawns inoculated by oral nasal route with 106 TCID BVDV2 • Fawns and calves housed in BL2 containment • No direct contactbetween two species • Calves fed with feeding equipment used by fawns, housed in deer contaminated rooms

  14. Isolation of virus • Virus first isolated from all three fawns on day 6 post inoculation of fawns • Virus isolated from 2 calves on day 11 post inoculation of fawns • All three calves seroconverted • Sequence of virus isolated from fawns matched sequence of virus isolated from calves

  15. Impact of BVDV infection in wildlife • Clinical presentation • Does infection have a signigicant negative impact?

  16. Experimental infection • Acute disease • Subclinical • Van Campen et al., 1997 • Clinically mild • Fever, reduced appetite, decrease in circulating lymphocytes (Ridpath et al, 2007) • Reproductive disease - Ridpath et al., 2008 • Infects dam, crosses placenta • Fetal death • Fetal reabsorption • Mummification • Expulsion • Persistent infection • Serum antibodies in dam protect fetus

  17. Reproductive Disease Does in 6th to 7th week of pregnancy Inoculated with 106 TCID BVDV1b or BVDV2a isolated from free living deer Housed in BL2 containment for entire experiment

  18. Results

  19. Impact in Wildlife Introduction or reintroduction of naïve species into ecosystem with circulating BVDV

  20. BDV in reintroduced chamois • Game animal hunted to near extinction in Europe • Successfully reintroduced to Pyrenes • Population die off reported • Marco et al, 2003 • Schelcher & Alzieu, 2003 • Clinical presentation • Depression • Weakness and difficulty in movement • Alopecia and hyperpigmentation • Caused by BDV

  21. BVDV in reintroduced big horn sheep

  22. Does a BVDV strain change when it is transmitted to a new host • Do changes occur? • Do changes affect detection or control?

  23. Adaptation of virus Binding No Binding

  24. Knowledge gaps • Prevalence of PI • Does virulence vary with species? • Does the virus change in response to new host? • What is the best approach to management of BVDV in free living ruminants?

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