Public asked to report sick or dead wild birds

DNREC’s Mosquito Control Section monitors West Nile virus
June 18, 2013

DNREC’s Division of Fish and Wildlife Mosquito Control Section is again asking the public’s help in monitoring West Nile virus in Delaware by reporting sick or dead wild birds of certain species that may have contracted the virus. West Nile virus is a mosquito-borne disease that rates of considerable concern to the health of humans and unvaccinated horses.

The Mosquito Control Section requests that the public report sick or dead birds of the following species only: crows, blue jays, cardinals, robins and hawks or owls, plus clusters of three or more sick or dead wild birds of any species. Bird specimens should have been dead for less than 24 hours and not appear to have died or been killed by other obvious causes. The collecting and testing of virus-suspect wild birds may continue through the end of September, said Dr. William Meredith, Delaware Mosquito Control administrator.

As with other parts of the country, West Nile virus had a resurgence in Delaware last summer, with nine human cases and one fatality during 2012. This disease is transmitted to humans primarily by the common house mosquito and possibly by Asian tiger mosquitoes. WNV first appeared in Delaware in 2001, with its peak year being 2003, with 17 reported human cases and two human fatalities, as well as 60 WNV-stricken horses. From 2004 through 2011, WNV numbers were lower in Delaware. Only one human case and one equine case of WNV were reported in 2011.

“Considering the prevalence and extent of prime mosquito production habitats in Delaware, combined with our high human population density, this can present quite a challenge, but our effective approach to controlling mosquitoes has helped reduce the frequency of West Nile virus transmission,” Meredith said.

For 2012, the Centers for Disease Control and Prevention’s nationwide figures show 5,674 reported human cases of West Nile virus resulting in 286 deaths, with the most cases occurring in descending order in Texas, California, Louisiana, Illinois, Mississippi, South Dakota, and Michigan.

“Over the past decade, WNV might have reduced populations in Delaware of some virus-susceptible birds such as crows, while surviving members of crows and other bird species may have become more resistant to the virus’ effects, perhaps as a type of flock immunity response,” Meredith said.

Due to complicated environmental reasons, wild birds are probably better indicators of WNV early in the season from May through July than Mosquito Control’s sentinel chickens, which become better indicators later, from August through October.  Within any given year, regardless of total numbers of cases, the gravest period of concern for disease transmission is in late summer and early fall, Meredith said.

Meredith also noted that there is no cause for alarm that uncollected specimens might transmit WNV to humans, or to pets that could consume a sick or dead bird. Dead birds can be left to decompose in place, or they can be buried, or bagged and disposed of in the garbage. He advises, when disposing of any dead bird to avoid direct skin contact by wearing gloves and/or by using a shovel.

Sick or dead birds can be reported to the Mosquito Control Section between 8 a.m. and 4 p.m., Monday through Friday, by calling Mosquito Control’s field offices:

Southern Kent County and all of Sussex County should call Mosquito Control’s Milford office at 302-422-1512

These numbers may also be used to report intolerable numbers of biting mosquitoes to help the Mosquito Control Section determine when and where to provide control services. For more information on Delaware’s Mosquito Control program, call the main office at 302-739-9917, or go to

Calls made to the field offices after business hours or during weekends or holidays can be recorded. Callers should give their name, phone number, address and a brief message. However, the public should be aware that some calls left more than 24 hours before Mosquito Control can review them - typically involving times between Friday evening and Sunday morning when staff might not be present - can unfortunately result in birds becoming too deteriorated for virus testing.

For more information about West Nile virus in humans, contact the Delaware Division of Public Health at 302-744-1033 or 888-295-5156. For more information about West Nile virus in horses, eastern equine encephalitis or vaccines, contact the state veterinarian at the Delaware Department of Agriculture at 800-282-8685, Delaware only, or 302-698-4500.