West Nile Virus is Detected in Delaware for First Time

West Nile Virus is Detected in Delaware for First Time This Year in DNREC’s Sentinel Chickens
No Human Cases of WNV Have Been Reported to Date in State

West Nile Virus (WNV) was detected Aug. 27 in Delaware for the first time this year in DNREC’s sentinel chickens placed at a northern New Castle County location where the chickens are sampled regularly for the presence of the mosquito-transmitted disease. While there have been no reported WNV cases in humans this year in the state, DNREC reminds Delawareans the possibility of contracting mosquito-transmitted diseases, including WNV and Eastern Equine Encephalitis (EEE), will continue until colder autumn temperatures, usually in mid-October or later.

DNREC’s Mosquito Control section in the Division of Fish and Wildlife collects blood samples each week from early July into October from the outdoor-caged sentinel chickens that are humanely housed and handled at 20 monitoring stations statewide. The blood samples are tested for WNV and EEE antibodies by the Delaware Public Health Laboratory. Sentinel chickens bitten by mosquitoes carrying WNV or EEE develop antibodies but are otherwise unaffected by the diseases. WNV and EEE can both be transmitted by mosquitoes to humans and horses.

Most people infected with WNV do not develop symptoms, but about 20% can develop a mild illness, which may include fever, body and muscle aches, headache, nausea, vomiting and rash. A small number of people can develop serious illness involving neurological problems, paralysis and possibly death. EEE is not as prevalent as WNV, but can present more severe symptoms in humans and horses.

The public is reminded to take common-sense precautions to avoid mosquito bites, including wearing long-sleeved shirts and long pants when outdoors in mosquito-prone areas, applying insect repellent containing 10 to 30% diethyl toluamide (DEET) in accordance with label instructions, and avoiding mosquito-infested areas and times of peak mosquito activity around dusk, dawn and at night.

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DNREC also may initiate mosquito spraying in areas where WNV or EEE is detected based on factors to include mosquito population levels and species present. To reduce mosquito-breeding habitat and chances of disease transmission, residents should drain or remove outdoor items that collect water, such as discarded buckets or containers, uncovered trashcans, stagnant birdbaths, unprotected rain barrels or cisterns, old tires, upright wheelbarrows, flowerpot liners, depressions in boat tarps, clogged rain gutters, corrugated downspout extenders and unused swimming pools.

Meanwhile, the state veterinarian within the Department of Agriculture urges horse owners to contact their veterinarians as soon as possible to have horses and other equines vaccinated against WNV and EEE. Neither disease has a specific drug treatment, and EEE infections in horses are fatal in 70 to 90% of cases, and WNV in 30% of cases.

More information is available from the following resources:

  • For mosquito biology/ecology and control, contact the Mosquito Control Section office in Dover at 302-739-9917.
  • For requests for mosquito relief in upstate areas from Dover north, contact Mosquito Control’s Glasgow field office at 302-836-2555.
  • For requests for mosquito relief in downstate areas south of Dover, contact Mosquito Control’s Milford field office at 302-422-1512.
  • For animal health questions, contact the Delaware% Department of Agriculture’s Poultry and Animal Health Section, at 302-698-4500.
  • To report suspected cases of human WNV, call the Division of Public Health Office of Infectious Disease Epidemiology at 888-295-5156.
  • For more information on West Nile virus or Eastern equine encephalitis, visit www.cdc.gov/ncidod/dvbid/westnile/index.htm.  

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