Public asked to report sick or dead wild birds to DNREC’s Mosquito Control Section for 2018 West Nile virus monitoring

The logo for the Department of Natural Resources and Environmental ControlDOVER – DNREC’s Mosquito Control Section within the Division of Fish & Wildlife is seeking the public’s help in monitoring West Nile virus in Delaware by reporting sick or dead wild birds that may have contracted the virus. West Nile virus (WNV) is a mosquito-borne disease of considerable concern to human health and to owners of 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, 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 from other obvious causes. Mosquito Control also notes that uncollected dead wild bird specimens are very unlikely to transmit WNV to humans or pets.

“We are again tracking when and where West Nile virus might appear in Delaware this year and monitoring its possible spread throughout the state,” said Dr. William Meredith, Mosquito Control Section administrator, DNREC Division of Fish & Wildlife. “Our sampling strategy is to collect and test birds from now into late September.”

Birds collected by DNREC are processed by the Delaware Department of Agriculture’s Poultry & Animal Health Lab, and then submitted to the Division of Public Health (DPH) Laboratory for virus testing. From July through mid- to late-October, DNREC’s Mosquito Control Section also operates a statewide network of about 20 sentinel chicken stations in prime mosquito areas. The DPH lab tests blood samples from the sentinel chickens for WNV and Eastern equine encephalitis (EEE), another mosquito-borne viral disease that affects humans and horses. The results help indicate where WNV or EEE has been transmitted by mosquitoes from wild bird hosts to other animals, possibly leading to an increased risk of exposure for humans or horses. Neither WNV nor EEE can be transmitted between horses or from horses to people.

The period of greatest concern for disease transmission for WNV and EEE is late summer and early fall. WNV is transmitted to humans primarily by the common house mosquito, and possibly by the Asian tiger mosquito. The disease first appeared in Delaware in 2001. Last year, Delaware had one human case and two equine cases, with the last cases of EEE detected in two horses in 2013. Nationwide, the Centers for Disease Control (CDC) logged 2,022 reported human cases of WNV last year resulting in 121 deaths, 10 of which occurred in our region.

Four other mosquito-borne diseases of concern that can occur in Delawareans are malaria, dengue fever, and chikungunya and Zika viruses. Cases of these four diseases are almost always found in travelers returning from tropical or sub-tropical regions where these illnesses are more prevalent. None involve wild birds as hosts, but rather are transmitted by mosquitoes from person-to-person.

To report sick or dead birds, call Mosquito Control’s field offices between 8 a.m. and 4 p.m., Monday through Friday:

  • New Castle County and Kent County from Dover north, Glasgow office: 302-836-2555
  • Remainder of Kent County and Sussex County, Milford office: 302-422-1512

Residents also are encouraged to call to report intolerable numbers of biting mosquitoes and request control services. Voicemail may be left after hours, or on weekends or holidays.

For more information, call Delaware Mosquito Control’s main office at 302-739-9917, or click Delaware Mosquito Control.

For more information about West Nile virus in humans, call the Delaware Division of Public Health at 302-744-4990 or 888-295-5156.

For more information about West Nile virus in horses, Eastern equine encephalitis, or vaccines, call the Delaware Department of Agriculture’s Poultry and Animal Health Section at 800-282-8685 (Delaware only) or 302-698-4500.

Follow the Division of Fish & Wildlife on Facebook, https://www.facebook.com/DelawareFishWildlife.

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

Vol. 48, No. 146


DNREC Mosquito Control Section’s spraying season to begin with larviciding wooded wetlands

DOVER – DNREC’s Mosquito Control Section within the Division of Fish & Wildlife will begin its annual spring woodland pool spraying campaign Saturday, March 17 on wooded wetlands near select populated areas in southern Sussex county, to treat mosquitoes’ immature aquatic larval stages. Treatment will be expanded statewide into Kent and New Castle counties during the upcoming weeks. In most years, a total of about 10,000 forested acres that produce large numbers of early-season mosquitoes are strategically sprayed, using larvicides applied by helicopter.

“The amount of larviciding needed is determined by woodlands locations and how wet they are, and can vary from year to year, depending on location and amount of precipitation from the past autumn, winter, and early spring,” said Delaware Mosquito Control Administrator Dr. William Meredith. “This year the extent of woodland pool coverage is slightly above the long-term average.”

Over the next several weeks, Mosquito Control will apply a bacterially-derived insecticide, Bti. “Like all registered insecticides used by Delaware Mosquito Control, the U.S. Environmental Protection Agency has determined that Bti, when used in accordance with EPA-approved product label instructions as required by federal law, can be applied without posing unreasonable risks to human health, wildlife or the environment,” Dr. Meredith said.

Aerial spraying of woodland pools must be completed before the forest canopy fills in, usually around mid-April, because foliage prevents the insecticide from reaching woodland pools and other wet spots on the forest floor harboring mosquito larvae. “If larval stages of early-season woodland pool mosquitoes are not successfully controlled, an intolerable number of biting adult mosquitoes could take wing in late April and remain through mid-June, becoming particularly troublesome within one to two miles of their woodland pool origins, and significantly affect quality of life and human health for residents and visitors alike,” said Dr. Meredith.

“Delaware has about 100,000 acres of wet woodlands during most springs, and it’s not possible for logistical or budgetary reasons to larvicide all woodland mosquito-producing habitats,” he said. “Targeting wet woodlands near populated areas is the best return-on-investment in providing mosquito relief to the most people.”

The spring campaign marks the beginning of Delaware’s annual mosquito season, which in most years continues until mid-October or early November, depending upon when the first killing freeze occurs. Control activities will be expanded starting in late April to contend with saltmarsh mosquitoes, myriad types of other freshwater mosquitoes, and urban and suburban container-breeding mosquitoes. Following the early spring larviciding campaign, Mosquito Control’s focus will turn to controlling adult mosquito populations and reducing bites from woodland pool mosquitoes that still emerge. Residents are also strongly encouraged to help reduce mosquito-producing habitat by doing some outdoor “spring cleaning,” and preventing or eliminating standing water sources throughout the season.

“Now is not too early for the public to take action to reduce backyard mosquito-producing habitats for species such as the Asian tiger mosquito that are known to carry illnesses such as West Nile virus and chikungunya as well as possibly Zika,” Dr. Meredith said, noting that this includes cleaning clogged rain gutters and downspout extenders, keeping fresh water in birdbaths, draining abandoned swimming pools, and preventing or emptying standing water from containers such as scrap tires, cans, buckets, flower pot saucers, unused water cisterns, children’s toys, upright wheelbarrows, uncovered trash cans, and depressions in tarps covering boats or other objects stored outside.

The public can learn about locations and times of spraying for adult mosquitoes via daily radio announcements, or by calling 800-338-8181 toll-free. Interested parties also may subscribe to receive email, text, or phone message spray announcements for their area by signing up on Mosquito Control’s Spray Zone Notification System at de.gov/mosquitospray.

To request localized mosquito control, please call Mosquito Control’s field offices:

  • Glasgow Office, 302-836-2555, serving New Castle County and the northern half of Kent County, including Dover.
  • Milford Office, 302-422-1512, serving the southern half of Kent County south of Dover and all of Sussex County.

For more information about Delaware’s Mosquito Control program, please call the Dover office at 302-739-9917.

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

Follow the Division of Fish & Wildlife on Facebook, https://www.facebook.com/DelawareFishWildlife.

Vol. 48, No. 60

-30-