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Mosquito-borne Viruses in Vermont

Mosquito-borne Viruses in Vermont. Mosquito-borne arboviruses inVT. West Nile virus (WNV) Eastern equine encephalitis (EEE) Arboviruses: Ar thropod – Bo rne- Viruses

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Mosquito-borne Viruses in Vermont

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  1. Mosquito-borne Viruses in Vermont

  2. Mosquito-borne arboviruses inVT • West Nile virus (WNV) • Eastern equine encephalitis (EEE) Arboviruses: Arthropod – Borne- Viruses Arthropod definition: invertebrate animals (as insects, arachnids, and crustaceans) that have a segmented body and jointed appendages, and achitinous exoskeleton Includes mosquitoes and ticks

  3. Eastern Equine Encephalitis Virus • Genus Alphavirus • Family Togaviridae • Outbreaks in horses recorded in 1831 • Virus isolated in 1933 • First human case confirmed in 1938 in MA • Select agent

  4. Culiseta melanura ? Aedes, Coquillettidia, Culex species

  5. EEE is Rare – Thankfully • Most pathogenic mosquito-borne disease in the US • Human case fatality rate ~35% • Death more common in older people • Among survivors, severe neurologic sequelae in ~50% (esp. children)

  6. Symptoms – Human • Incubation period 4 – 10 days • Systemic • Chills, fever, malaise, arthralgia, myalgia • Duration 1-2 weeks • Recovery complete as long as no CNS involvement • Encephalitic • Fever, headache, irritability, restlessness, drowsiness, anorexia, vomiting, diarrhea, cyanosis, convulsions, coma

  7. Other Species Affected horses and donkeys llamas and alpacas emus and pheasants also puppies, harbor seal, cow, African penguin, deer Vaccine licensed for horses – may also be effective in llamas, alpacas and emus

  8. What Did We Know about EEE in VT? • Until 2010 no evidence of the virus detected in VT • Surveillance • Passive human and veterinary surveillance • Limited mosquito surveillance • Seemed likely to be here… • Found in neighboring states and Quebec • Acidic hardwood swamps and vector species present • Activity increasing in general in northeast?? • New foci in ME and NH • Increases in human cases in MA

  9. Mosquito Surveillance Culiseta Habitat • Acidic swamps (red maple, cedar) • Crypts formed by pockets of water surrounding tree roots • Brandon, Leicester, Salisbury area • Adults emerge in April and May with second emergence in late June/July

  10. Resting Box • Passive collecting device • Serves as a resting place for blooded mosquitoes from dawn to noon • Attracts blooded, gravid, and host-seeking Culiseta melanura

  11. Deer Serosurvey for EEE virus • 2010 hunting season • Deer get bitten by a lot of mosquitoes • Develop detectable antibodies • Survive infection although clinical illness has been reported • Limited range – ~1 square mile in summer • Blood readily available • 513 blood samples collected from deer and moose at check stations during youth weekend and opening weekend of rifle season • Samples sent to CDC to test for antibodies against EEEV

  12. Deer serosurvey - equipment

  13. Results of 2010 Serosurvey Deer – 50/489 (10.2%) Moose – 6/21 (28.6%) 8 positive yearlings

  14. What Did Deer Serosurvey Mean? • EEE virus is present in Vermont • Need to keep up surveillance – both human and veterinary • More complete mosquito surveillance would be nice, but expensive • Continue to educate Vermonters about preventing mosquito bites

  15. Deer Serosurvey: 2010 - 2012

  16. EEE in VT emus • Sept 21, 2011 – report of ill emus • Southern Rutland County – near large acidic swamp • Several emus in a flock developed hemorrhagic gastroenteritis; ataxia • Earliest onset 9/15 • By 9/21, 14 emus had died • Last death on 9/24 • 19/93 died, 2 ill birds recovered • All ages affected

  17. Plans for 2013 • Mosquito surveillance in known EEE area • Surveillance data available on-line • Human and veterinary surveillance • Education to residents • preventing mosquito bites • On-line availability of a risk-map • Updated throughout the season

  18. WNV & EEE Prevention • Promote use of personal protection • Long sleeves and pants • Insect repellent that contains DEET, Picaridin, or oil of lemon eucalyptus • Cover baby carriages with mosquito netting • Fix holes in screens • Avoid outdoor activities when mosquitoes are active • Eliminate mosquito breeding habitats • Reduce standing water • Vaccinate horses and other susceptible animals

  19. Thank You

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