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Skip Navigation LinksDNREC : News : Delaware’s first finding of West Nile virus in wild birds reported for 2014

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Contact: Joanna Wilson, DNREC Public Affairs, 302-739-9902 

Delaware’s first finding of West Nile virus
in wild birds reported for 2014

DOVER (Aug. 15, 2014) – An American crow submitted to the Delaware Division of Public Health Laboratory by DNREC’s Mosquito Control Section on Aug. 6 has tested positive for West Nile virus, as reported by the lab on Aug. 11. The bird was collected in North Wilmington. West Nile virus is a mosquito-borne disease that affects humans and horses. 

“The Mosquito Control Section will respond to this West Nile virus-positive bird by increasing our mosquito population surveillance-and-monitoring activities in this area, and will take appropriate follow-up mosquito control actions as warranted,” said DNREC Mosquito Control Section Administrator Dr. William Meredith.

To date, no other findings of West Nile virus have been reported this year in Delaware, as WNV has not yet been detected in any other wild birds collected by or submitted to Mosquito Control, or been diagnosed in any humans or horses. West Nile also has not yet been found by the Mosquito Control Section’s statewide network of 20 sentinel chicken monitoring stations, which have been in operation since mid-July.

Another mosquito-borne disease that also affects humans and horses, Eastern equine encephalitis (EEE) virus, has not been detected in Delaware this year. However, peak activity in the mid-Atlantic region for both West Nile virus and EEE typically occurs from about the first week in August through the second week in October, so findings in host wild birds or mosquitoes could occur and increase over the next several weeks, with possible transmission to humans or horses. In addition to ongoing WNV and EEE awareness, DNREC’s Mosquito Control Section and the Delaware Division of Public Health are also vigilant in Delaware about a third mosquito-transmitted disease, chikungunya. The state experienced its first human case of chikungunya in early July, and although that case was related to foreign travel, local transmission can become more likely as the disease spreads throughout the country.

Dr. Heather Hirst, State Veterinarian with the Delaware Department of Agriculture, said effective equine vaccines exist to protect horses from both WNV and EEE. “I am urging horse owners to assist with prevention efforts by making sure their horses are vaccinated against both WNV and EEE,” Dr. Hirst said. “Initially, two doses of the vaccine are necessary for immunization. After the initial two vaccinations, a yearly booster is needed. Horse owners should consult their local veterinarian for advice on vaccination protocols. If horses have not been vaccinated or have only recently been vaccinated, owners should keep horses inside during peak mosquito times, i.e., dawn, dusk, and throughout the night.”

There are no approved WNV or EEE vaccines for humans. Approximately 80 percent of human WNV infections are mild and cause no apparent symptoms. Nearly 20 percent of those infected develop a mild illness (West Nile fever), which includes fever, body and muscle aches, headache, nausea, vomiting, and rash. A small percentage of patients, usually the elderly, develop severe neurological disease that results in meningitis or encephalitis.

"This finding of West Nile virus in Delaware serves as a good reminder for people to take common-sense precautions against mosquito bites,” Dr. Meredith said. These include wearing long-sleeved shirts and long pants when outdoors in mosquito-prone areas, applying insect repellent containing10- to 30-percent DEET* in accordance with all label instructions, and avoiding mosquito-infested areas or times of peak mosquito activity around dusk, dawn or throughout the evening.

Mosquito repellents containing DEET can be applied to the skin but will last only a few hours before reapplication is necessary. The current American Academy of Pediatrics (AAP) and CDC recommendation for children older than 2 months of age is to use 10- to 30-percent DEET, the mosquito repellent. DEET should not be used on children younger than 2 months of age. The effectiveness is similar for 10 to 30 percent DEET but the duration of effect varies: 10 percent DEET provides protection for about 2 hours, and 30 percent protects for about 5 hours. Choose the lowest concentration that will provide the required length of coverage.

"We know that insect bites are not only annoying and sometimes painful, but can be dangerous as well," said Dr. Karyl Rattay, Division of Public Health Director. “It's better medicine to prevent insects from biting you at all.”

To reduce mosquito-breeding, Dr. Meredith said people should drain or remove items that collect water, such as discarded buckets or containers, uncovered trash cans, stagnant birdbaths, unprotected rain barrels or cisterns, old tires, upright wheelbarrows, flowerpot liners, depressions in tarps covering boats, clogged rain gutters, downspout extenders, and unused swimming pools.

“The possibility of mosquito-borne disease transmissions now won’t subside until cooler autumn temperatures set in, usually in mid-October and sometimes even later,” he added.

To help determine when and where control services are needed, the Mosquito Control Section encourages residents to report intolerable numbers of biting mosquitoes by calling the numbers below. Phones are answered between 8 a.m. and 4 p.m. Monday through Friday. Callers after business hours or during weekends or holidays should leave their name, phone number, address and a brief message. 

  • Glasgow Office, serving New Castle County and northern Kent County (including the Dover area): 302-836-2555

  • Milford Office, serving Sussex and southern Kent Counties: 302-422-1512

For more information about:

  • Mosquito biology/ecology and control – Contact the Mosquito Control Section’s Dover office at 302-739-9917.

  • WNV in humans and related medical issues – Contact the Delaware Division of Public Health at 888-295-5156.

  • WNV or EEE in horses and equine vaccines – Contact the Department of Agriculture’s Poultry and Animal Health Section at 302-698-4500 or 800-282-8685 (Delaware only).

  • West Nile virus – visit the CDC website,

  • Chikungunya – visit the CDC website,  

Vol. 44, No. 246

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