1. West Nile Virus Bug of the Month Health begins where we live, learn, work, & play

2. 2 West Nile Virus – Outline of Session  Brief History of WNv  Clinical Presentation of WNv  Transmission of WNv  WNv Basics  Protect Yourself from WNv – 5 “Ds”  WNv Surveillance  Questions

3. 3 A Brief History of WNv  1937 - first identified in Uganda  1999 - first identified in North America around New York City  2000 - spread to adjoining states  2001 - positive birds in Ontario  2002: Human disease in southern Ontario, Quebec First positive bird in Regina  2003 - first human case reported in Saskatchewan in July No symptoms Discovered during blood donor screening

4. 4 Clinical Presentation  Incubation period in humans is 3-14 days  Most infections are mild: ~80% are asymptomatic infections ~20% develop a mild illness  headache  muscle pains  rash  nausea  vomiting

5. 5 Clinical Presentation  ~1 in 150 people develop neurologic symptoms (encephalitis)  People at greater risk of serious disease from WNv infection are the elderly and people with weakened immune systems WNv is a reportable (notifiable) disease in Saskatchewan.

6. How is WNv Transmitted?

7. West Nile Virus Transmission Cycle West Nile virus Enzootic and amplification vector? Incidental infections Bird reservoir hosts? Bridge vectors? Unknown vertebrate cycle(s)?? Incidental infections

8. 8 WNv Basics?  Flavivirus family  A disease of birds, transmitted from bird to bird by mosquitoes that feed almost exclusively on birds or through birds preying on other birds or mammals  > 160 different species of birds so far (CDC)  Humans and horses are infected “accidentally” by mosquitoes which feed on both birds and mammals  8 mosquito species in Saskatchewan are carriers of WNV but Culex tarsalis is the main carrier

9. 9 Mosquito Biology  The female mosquito “bites”  Blood is required for egg production  Host(s) varies with mosquito species  Most species in Saskatchewan have single generation per year with over-wintering in egg stage  Some species have multiple generations and “hibernate” as adult females (Culex tarsalis)

11. Protect Yourself from WNV Five Ds  DEET  DRAIN  DUSK and DAWN  DRESS  DOORS

12. 12 Prevention – FIVE “Ds”  Wear a good insect repellant with DEET. Apply according to directions.  DRAIN standing water. Mosquitoes require water to complete their life cycle. Eliminate or reduce all sources of standing water where mosquitoes can lay eggs, like wading pools, wheelbarrows, containers, rain downspouts and gutters, pet dishes and birdbaths, etc. Reduce places in the yard where adult mosquitoes can thrive - like tall grasses and weeds.  Avoid going out during DUSK and DAWN. The mosquitoes that carry West Nile virus are most active at dawn and dusk and also in the early evening. They are especially active for two hours after sunset.  DRESS appropriately. Wear long sleeves and long pants (wear light-weight clothing to minimize the potential for heat-induced illnesses). Mosquitoes may be more attracted to individuals wearing perfumes and colognes.  Mosquito-proof your home. Make sure that DOORS and windows have tight fitting screens. Repair or replace screens that have tears or holes.

13. Surveillance

14. 14 Mosquito Surveillance - 2012  The mosquito surveillance program in Sun Country Health Region began in 2012 during the week of June 12.  Mosquito traps have been set up in Estevan and Weyburn and these traps are key indicators in the provincial mosquito surveillance program.

15. 15 Culex tarsalis Mosquitoes  Culex tarsalis are warm weather mosquitoes and will produce multiple generations when conditions are right.  Mosquito populations can be estimated based on the number of heat days during the season i.e. the number of days when the temperature does not drop below 14.3 degrees Celsius.

18. 18 WNv Risk - 2012  With the hot weather and rain we have been experiencing, the conditions are optimal for the development of Culex tarsalis and WNv  The extrinsic incubation period (EIP) of the virus within the mosquito will be short (i.e. 5 – 7 days) and we may see infected mosquitoes over the next couple of weeks.

19. 19 What’s in store for us?  5 positive mosquito pools in Manitoba to date  First human cases identified in S Dakota  Will likely start to see positive mosquitoes in our area soon.  Ontario had cases last year and may have many more this year.  This could be a building year where the virus is amplified and could bring higher prevalence next year.

20. 20 West Nile Virus – Map of Risk Risk Map  http://www.health.gov.sk.ca/west- nile-risk http://www.health.gov.sk.ca/west- nile-risk Estimated risk levels: July 12, 2012 (CDC Week 28)  Low (yellow) WNV mosquito development. Take precautions against mosquito bites.

21. 21 WNV-positive Mosquito Pools YearSun CountrySaskatchewan 2011 3 (1 st positive in week 32) 4 2009 11 (1 st positive in week 29) 11 2007 219 (1 st positive in week 25) 460 200337

23. 23 Human WNV in SCHR  2011 - No human cases of WNV reported in Saskatchewan.  2010 - Two human cases of WNV were reported in SCHR and these individuals were believed to have been infected in early August (no other cases in Saskatchewan). Following the 2003 WNv season - a 2004 study in FHHR estimated the seroprevalence rate of WNV in FHHR was 9.98%. The seroprevalence in southern Saskatchewan following the 2007 WNv season was estimated to be less than 5%.

24. 24 Human WNV in SCHR YearSun CountrySaskatchewan 2008117 2007119 2006920 2003100947

25. 25 WNV in Horses in SCHR YearSun CountrySaskatchewan 201111 200900 2007157 2003133

26. 26 West Nile Virus – Information Sources  West Nile Virus Brochure http://www.health.gov.sk.ca/west- nile-brochure http://www.health.gov.sk.ca/west- nile-brochure  Resources on WNV and prevention http://www.health.gov.sk.ca/west- nile-virus-awareness-prevention http://www.health.gov.sk.ca/west- nile-virus-awareness-prevention  CDC Question and Answers on WNv http://www.cdc.gov/ncidod/dvbid/we stnile/qa/overview.htm http://www.cdc.gov/ncidod/dvbid/we stnile/qa/overview.htm

27. 27 West Nile Virus – Information Sources  Risk Map http://www.health.gov.sk.ca/west-nile- risk http://www.health.gov.sk.ca/west-nile- risk  Human and Mosquito Surveillance http://www.health.gov.sk.ca/wnv- surveillance-results http://www.health.gov.sk.ca/wnv- surveillance-results  Weekly Reports on WNv http://www.health.gov.sk.ca/west-nile- culex-reports http://www.health.gov.sk.ca/west-nile- culex-reports  Report of the 2004 West Nile Virus Seroprevalence Studies in Saskatchewan http://www.health.gov.sk.ca/west-nile- seroprevalence

28. Questions? Call us anytime at 842-8618 if you have questions about Public Health.

29. 29 Public Health Inspection Contacts  Weyburn Office 842-8618  Grant Paulson PHI Supervisor  Ken Cross PHI  Kristin Waroma PHI  Estevan Office 637-3626  Tom Shaw PHI  Kendra Hale PHI