west nile virus on the prairies
DESCRIPTION
West Nile virus on the Prairies. Tasha Epp, DVM, PhD October 5, 2010. WNV 1999, New York. Spread across USA - 1999. Spread across USA - 2000. Spread across USA - 2001. Spread across USA – 2002. Spread across USA - 2003. Great Plains and WNv. Birds and WNv. Virus. Family: Flaviviridae - PowerPoint PPT PresentationTRANSCRIPT
West Nile virus on the West Nile virus on the PrairiesPrairies
Tasha Epp, DVM, PhDTasha Epp, DVM, PhD
October 5, 2010October 5, 2010
WNV 1999, New YorkWNV 1999, New York
Spread across USA - 1999Spread across USA - 1999
Spread across USA - 2000Spread across USA - 2000
Spread across USA - 2001Spread across USA - 2001
Spread across USA – 2002Spread across USA – 2002
Spread across USA - 2003Spread across USA - 2003
Great Plains and WNvGreat Plains and WNv
Birds and WNvBirds and WNv
VirusVirus
Family: FlaviviridaeFamily: Flaviviridae Genus: Flavivirus Japanese Encephalitis Genus: Flavivirus Japanese Encephalitis
Antigenic complexAntigenic complex– Includes JE, WNV, Kunjin, Murray Valley Includes JE, WNV, Kunjin, Murray Valley
encephalitis, SLE, etcencephalitis, SLE, etc– RNA, single strandedRNA, single stranded
Natural CycleNatural Cycle
Species affectedSpecies affected
BirdsBirds MosquitoesMosquitoes
Humans, horsesHumans, horses
alpacas, camels, alpacas, camels, sheep, squirrels, sheep, squirrels, reptiles, etcreptiles, etc
Clinical DiseaseClinical Disease
HumansHumans– Asymptomatic Asymptomatic – WNV FeverWNV Fever– WNV neuro-invasiveWNV neuro-invasive
Other mammals or birdsOther mammals or birds– Neurological symptoms (mild to severe)Neurological symptoms (mild to severe)– DeathDeath
Long Term Outcomes - HumansLong Term Outcomes - Humans
Symptoms reported “post-recovery”Symptoms reported “post-recovery”– Self-reported fatigueSelf-reported fatigue– Memory problemsMemory problems– Extremity weaknessExtremity weakness– Word-finding difficultyWord-finding difficulty– HeadachesHeadaches– DepressionDepression– Attention deficitsAttention deficits
Surveillance in Prairies from 2002-Surveillance in Prairies from 2002-20102010
2002 2002 – Humans, horses and birds in ManitobaHumans, horses and birds in Manitoba– first bird and clinical horses reported in SKfirst bird and clinical horses reported in SK
2003 2003 – epidemic (birds, horses, humans, etc) in SK and MBepidemic (birds, horses, humans, etc) in SK and MB– First cases in AB First cases in AB
2004 – 2006 2004 – 2006 – Mild years, very few casesMild years, very few cases
2007 2007 – epidemic returns in full force on prairiesepidemic returns in full force on prairies
2008-20102008-2010– Few cases reportedFew cases reported
2003: Horse, bird, human and mosq.2003: Horse, bird, human and mosq.
Five Hills Health RegionFive Hills Health Region
Highest reported number of cases in SKHighest reported number of cases in SK SeroprevalenceSeroprevalence
– Overall 9.8% (7.4, 12.6)Overall 9.8% (7.4, 12.6)– Rural only 16.8%Rural only 16.8%– Urban only 3.2%Urban only 3.2%
Rural versus urban:Rural versus urban:– 6 times more likely to be positive (95% CI: 3, 6 times more likely to be positive (95% CI: 3,
13)13)
Present Surveillance in SKPresent 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.
Occupational DataOccupational Data
Mosquito exposure Mosquito exposure – Rural residents or workers Rural residents or workers
FarmersFarmers Outdoor jobs or recreationOutdoor jobs or recreation
Tissue or fluid exposureTissue or fluid exposure– Laboratory, field or clinical workersLaboratory, field or clinical workers
People involved in dead bird collectionPeople involved in dead bird collection Veterinarians Veterinarians Pathologists Pathologists
Precautions for workersPrecautions for workers
Using an effective insect repellent helps prevent mosquito bites.Photograph courtesy of CDC/PHPPO/DPDE/CAB/PhotoServices.
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
Control Measures:Control Measures:
Source reductionSource reduction– Remove standing water, etcRemove standing water, etc
Mosquito controlMosquito control– Personnel protectionPersonnel protection– LarvicidingLarviciding– AdulticidingAdulticiding
VaccinationVaccination Behavior modificationBehavior modification
Mosquito ControlMosquito Control
Preferred Preferred method for method for surveillance in surveillance in SKSK
Best prevention Best prevention of infection in of infection in people?people?
Vaccination?Vaccination?
Is this feasible?Is this feasible? Who would get vaccinated?Who would get vaccinated? Cost-benefit analysis?Cost-benefit analysis?
Human Behavior?Human Behavior?
DEETDEET DrainDrain DressDress Dusk to dawnDusk to dawn
Northern Colorado studyNorthern Colorado study
Loveland and Fort CollinsLoveland and Fort Collins Similar ecology, demographicsSimilar ecology, demographics
– High plains ecoregionHigh plains ecoregion– 90% white, around 10% >65 yrs90% white, around 10% >65 yrs
Loveland had mosquito control programLoveland had mosquito control program– Less WNV-infected mosquitoes than Fort Less WNV-infected mosquitoes than Fort
CollinsCollins
Loveland had higher neuro-Loveland had higher neuro-invasive disease rateinvasive disease rate– Loveland = 38.6/100,000Loveland = 38.6/100,000– Fort Collins = 15.9/100,000Fort Collins = 15.9/100,000
Northern Colorado studyNorthern Colorado study
Northern Colorado studyNorthern Colorado study
Loveland residents Loveland residents – reported less use of DEETreported less use of DEET
Most influenced by ageMost influenced by age Second influenced by risk perceptionSecond influenced by risk perception
– more likely to spend time outdoors at more likely to spend time outdoors at dusk and dawn dusk and dawn both weekdays and weekendsboth weekdays and weekends
– Long clothes not importantLong clothes not important
First Nations and WNvFirst Nations and WNv
Identified many activities resulting in Identified many activities resulting in exposureexposure
Identified features of homes or yards Identified features of homes or yards resulting in exposureresulting in exposure
Control measuresControl measures– Smoke or Mosquito coils Smoke or Mosquito coils – DEET based productsDEET based products– Clothing (children versus adults)Clothing (children versus adults)
Communicating RiskCommunicating Risk
When?When? How?How? What?What?
Future of WNvFuture of WNv
What should we expect?What should we expect?
Is WNv here to stay?Is WNv here to stay?
Can we predict WNv years before they Can we predict WNv years before they occur?occur?
Questions?Questions?