West Nile Virus Detected in Maryland

Aedes triseriatus mosquito
PHOTO | CDC Robert S. Craig

The Maryland Department of Agriculture (MDA) has announced the first detection of a West Nile virus (WNV) mosquito pool in Maryland this summer.

On August 5th, the Maryland Department of Health and Mental Hygiene (DHMH) confirmed the presence of WNV in mosquitoes collected by MDA personnel in the City of Bowie in Prince George’s County. ULV spraying to control adult mosquitoes in that section of Bowie occurred the night following trapping. MDA mosquito control personnel are working aggressively to reduce mosquito populations in this community and across the state of Maryland.

“We know that West Nile virus may be present throughout Maryland. It typically appears at this time in the summer, so we are not surprised with this positive finding,” says Secretary of Agriculture Joe Bartenfelder. “The confirmation of virus-positive mosquitoes serves as a reminder to all residents to continue protecting themselves against mosquito bites and to conduct backyard mosquito control activities in addition to MDA’s routine surveillance and spray activities.”

The MDA Mosquito Control Office, in cooperation with DHMH, has been conducting surveillance activities throughout the State to collect and test mosquitoes for WNV, Eastern Equine Encephalitis (EEE) and several other mosquito-borne diseases. These diseases are endemic in Maryland and are transmitted through the bite of a mosquito. Approximately 20 percent of people infected with WNV will develop West Nile fever, which is typically characterized by fever, headache, and body aches which can last for just a few days or as long as several weeks. Less than one percent of people bitten by a mosquito carrying West Nile virus will develop a more severe form of the disease. People most at risk for developing severe disease are those over 50 and those with already compromised immune systems.

While not all mosquitoes carry these diseases, MDA suggests that residents take precautions to minimize their exposure to mosquito bites.

These measures include:

–Wear long, loose fitting, light colored clothing.
–Wear insect repellents according to product labels.
–Avoid mosquito infested areas during prime periods of activity (between dusk and dawn).
–Install, inspect, and repair window and door screens in homes and stables.
–Regularly clean bird baths and bowls for pet food and water.
–Remove or empty all water-holding containers.

Currently there is no WNV vaccine for humans. There are, however, effective vaccines for horses, ostriches and emus – also known as ratites. Owners are encouraged to get their animals vaccinated and boostered in a timely manner in consultation with their veterinarian.

Dog owners are also urged to have their pets checked for heartworms, the most common disease transmitted by mosquitoes in Maryland. Dogs in all Maryland jurisdictions should be placed on a heartworm preventive program. Pet owners should consult with their veterinarians.

For more information about mosquito-borne diseases, contact your local health department. The following websites provide even more information:

–MDA, mda.maryland.gov/plants-pests/Pages/mosquito_control.aspx
–DHMH, dhmh.maryland.gov
–Maryland Department of Natural Resources, dnr.maryland.gov
–Centers for Disease Control and Prevention, cdc.gov/westnile

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