1. West Nile virus on the Prairies Tasha Epp, DVM, PhD October 5, 2010

2. WNV 1999, New York

4. Spread across USA - 1999

5. Spread across USA - 2000

6. Spread across USA - 2001

7. Spread across USA – 2002

8. Spread across USA - 2003

9. Great Plains and WNv

10. Birds and WNv

11. Virus  Family: Flaviviridae  Genus: Flavivirus Japanese Encephalitis Antigenic complex –Includes JE, WNV, Kunjin, Murray Valley encephalitis, SLE, etc –RNA, single stranded

12. Natural Cycle

13. Species affected  Birds  Mosquitoes  Humans, horses  alpacas, camels, sheep, squirrels, reptiles, etc

14. Clinical Disease  Humans –Asymptomatic –WNV Fever –WNV neuro-invasive  Other mammals or birds –Neurological symptoms (mild to severe) –Death

15. Long Term Outcomes - Humans  Symptoms reported “post-recovery” –Self-reported fatigue –Memory problems –Extremity weakness –Word-finding difficulty –Headaches –Depression –Attention deficits

16. Surveillance in Prairies from 2002- 2010  2002 –Humans, horses and birds in Manitoba –first bird and clinical horses reported in SK  2003 –epidemic (birds, horses, humans, etc) in SK and MB –First cases in AB  2004 – 2006 –Mild years, very few cases  2007 –epidemic returns in full force on prairies  2008-2010 –Few cases reported

17. 2003: Horse, bird, human and mosq.

18. Five Hills Health Region  Highest reported number of cases in SK  Seroprevalence –Overall 9.8% (7.4, 12.6) –Rural only 16.8% –Urban only 3.2%  Rural versus urban: –6 times more likely to be positive (95% CI: 3, 13)

19. Present Surveillance in SK Regardless of the risk rating for your region, remember that there is no such thing as "risk-free". If you can be bitten by a mosquito, you can contract West Nile Virus. Source: Saskatchewan Ministry of Health, Population Health Branch Minimal Few West Nile Virus mosquitoes present. Minimal risk does not mean no risk; take precautions against mosquito bites. Low WNV mosquito development. Take precautions against mosquito bites. Moderate The mosquito species that carries West Nile Virus has been recorded in numbers that warrant extra precautions. High WNV-positive mosquitoes identified in significant numbers. Precautions against mosquito bites should be taken at all times.

20. Occupational Data  Mosquito exposure –Rural residents or workers  Farmers  Outdoor jobs or recreation  Tissue or fluid exposure –Laboratory, field or clinical workers  People involved in dead bird collection  Veterinarians  Pathologists

21. Precautions for workers Using an effective insect repellent helps prevent mosquito bites. Photograph courtesy of CDC/PHPPO/DPDE/CAB/Ph otoServices. Long-sleeved shirts, long pants, and socks will help prevent mosquito bites. Photograph courtesy of Joe Larson, USDA. http://www.cdc.gov/niosh/docs/2005-155/ http://www.phac-aspc.gc.ca/ols-bsl/wnvbio-eng.php

22. Control Measures:  Source reduction –Remove standing water, etc  Mosquito control –Personnel protection –Larviciding –Adulticiding  Vaccination  Behavior modification

23. Mosquito Control  Preferred method for surveillance in SK  Best prevention of infection in people?

24. Vaccination?  Is this feasible?  Who would get vaccinated?  Cost-benefit analysis?

25. Human Behavior?  DEET  Drain  Dress  Dusk to dawn

26. Northern Colorado study  Loveland and Fort Collins  Similar ecology, demographics –High plains ecoregion –90% white, around 10% >65 yrs  Loveland had mosquito control program –Less WNV-infected mosquitoes than Fort Collins

27.  Loveland had higher neuro- invasive disease rate –Loveland = 38.6/100,000 –Fort Collins = 15.9/100,000 Northern Colorado study

28.  Loveland residents –reported less use of DEET–reported less use of DEET  Most influenced by age  Second influenced by risk perception –more likely to spend time outdoors at dusk and dawn  both weekdays and weekends –Long clothes not important–Long clothes not important

29. First Nations and WNv  Identified many activities resulting in exposure  Identified features of homes or yards resulting in exposure  Control measures –Smoke or Mosquito coils –DEET based products –Clothing (children versus adults)

30. Communicating Risk  When?  How?  What?

31. Future of WNv  What should we expect?  Is WNv here to stay?  Can we predict WNv years before they occur?

32. Questions?