Contact Michael Globetti, DNREC Public Affairs 302-739-9902. 

Public asked to report sick or dead wild birds to DNREC’s
Mosquito Control Section for West Nile virus monitoring 

DOVER (May 13, 2011) – DNREC’s Mosquito Control Section is again asking the public’s help in monitoring West Nile virus in case of an occurrence of the disease – 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 human health and unvaccinated horses.

Beginning Monday, May 16, 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 five 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’s Mosquito Control administrator. 

After initial processing by the Delaware Department of Agriculture’s Poultry & Animal Health Lab, bird specimens collected by the Mosquito Control Section will be submitted to the Delaware Public Health Laboratory for virus testing. From early July through mid- or late October, the Mosquito Control Section will also operate its statewide network of some 23 sentinel chicken stations – which “keep watch” for West Nile virus and for eastern equine encephalitis, another mosquito-borne disease affecting horses and humans.

No human cases of West Nile virus have been reported in Delaware since 2008, when there was one case, the same number as the year before, according to Dr. Meredith. However, in 2003, the state had 17 reported human cases and two human fatalities from West Nile virus, which is primarily transmitted by the common house mosquito. That year there were also six stricken horses. In 2004 and 2006, no cases of West Nile virus were reported in humans or horses; in 2005 two human cases were reported, with no horse cases.

“Mosquito Control’s effective approach to controlling the mosquitoes that transmit it has helped prevent significant outbreaks of West Nile virus in Delaware the last few years, with an assist from the seemingly natural (but still poorly understood) cycles for the occurrence of West Nile,” Dr. Meredith said, noting that the numbers of cases have risen in other states. For 2010, the Centers for Disease Control’s (CDC) nationwide figures show 981 reported human cases of West Nile virus resulting in 45 deaths, with the most cases occurring, in descending order, in Arizona, New York, California, Texas, Colorado, Illinois, Nebraska, New Jersey and Pennsylvania.

During its decade in Delaware, West Nile virus may have reduced populations of some virus-prone birds such as crows, while surviving members of other bird species may have become more resistant to the virus’ effects, Dr. Meredith said. With West Nile virus not quite as alarming to the public as when it first surfaced, the reporting of sick or dead wild birds may have diminished in importance. This was evident when a decline in the submission of wild bird specimens prompted the Mosquito Control Section to suspend its collection and testing of wild birds in 2010. But the Section has resumed testing this year at the urging of the CDC.

Wild birds, due to complicated epizootic reasons, are probably better indicators of West Nile virus early in the season (from May through July) than are Mosquito Control’s sentinel chickens, which become better indicators later (August through October). Weather conditions could also impact this year’s West Nile numbers, whether found in wild birds, sentinel chickens or mosquitoes themselves, as evidence suggests outbreaks might be more severe during abnormally hot years – with the peak concern for transmission in late summer and early fall, Dr. Meredith said.

The Mosquito Control Section also will continue to document all phone reports of West Nile species of interest, but will be selective in collecting and analyzing reported birds. As the season progresses, Mosquito Control will cease analyzing specimens from areas where a number of virus-positive birds have been found, although it will continue to solicit public reporting of virus-suspect birds for these areas.

Dr. Meredith also noted that there is no cause for alarm that uncollected specimens might transmit West Nile virus to humans or to pets that could consume a sick bird or its carcass. Dead birds can be left to decompose in place, or they can be buried, or bagged and disposed of in the garbage. When handling any dead bird, you should avoid direct skin contact by wearing gloves or by using a shovel to dispose of the carcass.

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 the section’s field offices:

• New Castle County and northern Kent County from Dover north (Glasgow office): 302-836-2555
• Remainder of southern Kent County and all of Sussex County (Milford office): 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 programs, please call the main office at 302-739-9917, or visit http://www.dnrec.delaware.gov/fw/Services/Pages/MosquitoSection.aspx. 

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 about the finding. However, the public should be aware that some calls left more than 24 hours before Mosquito Control can review them (usually between Friday evening and Sunday morning) usually result in the bird becoming too deteriorated for virus testing.

For more information about West Nile virus in humans, please contact the 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, please contact the State Veterinarian at the Department of Agriculture at 800-282-8685 (Delaware only) or 302-698-4500.

Vol. 41, No. 185