West Nile Virus and EEE Detected in Maryland Mosquitoes

Mosquitoes collected in two separate areas of Prince George's County are the first in Maryland this year to test positive for West Nile virus (WNV) and for Eastern equine encephalomyelitis (EEE). In the first instance, mosquitoes collected on July 19 from a trap in Cottage City tested positive for WNV. Mosquitoes collected on July 22 inside the Patuxent Wildlife Refuge near Bowie have tested positive for EEE. Laboratory tests from the Maryland Department of Health and Mental Hygiene confirmed the presence of the diseases in the mosquitoes on August 4 and 5 respectively.
"We know that West Nile virus is present throughout Maryland and are not surprised to find mosquitoes in this area testing positive for that virus," says Secretary of Agriculture Lewis R. Riley. "Triple E-positive mosquitoes are, however, found more frequently on the Lower Eastern Shore than west of the Bay. The confirmation of virus-positive mosquitoes serves as a reminder to all residents that it is very important to continue to protect themselves against mosquito bites and to conduct backyard mosquito control activities."
The Maryland Department of Agriculture (MDA) mosquito control office, with the Maryland Department of Health and Mental Hygiene, is conducting statewide surveillance activities to monitor mosquito populations and detect mosquito-borne viruses of public health concern. Surveillance activities for adult mosquitoes use traps and landing rate counts. Mosquito control activities conducted by MDA include larvaciding and spray programs for adult mosquitoes in communities that voluntarily participate in the agency's program.

There are effective vaccines against both viruses for horses, ostriches, and emus (also known as ratites) and owners are encouraged to get their animals vaccinated and boostered in a timely manner in consulation with their veterinarian.

The last reported human case of EEE in Maryland was in 1989. The state's last reported cases of equine EEE was during last year's exceptionally rainy season. The human and horse cases occurred on the Lower Eastern Shore. The last time a mosquito collection tested positive for EEE on the Western Shore was approximately 10 years ago, also on the Patuxent Wildlife Refuge.

For more information about mosquito-borne diseases, contact your local health department. The following web sites are available to provide additional information: arboviral encephalitis, www.edcp.org/factsheets/arboviral.html; West Nile virus, www.edcp.org/factsheets/wnv_fact.html and www.aphis.usda.gov/lpa/issues/wnv/wnv.html; the MDA, www.mda.state.md.us, and the Centers for Disease Control and Prevention (CDC) at www.cdc.gov/ncidod/dvbid/westnile/

For more information about Maryland's WNV-surveillance program, contact the MDA mosquito control office at 301/927-8357 or 877/425-6485 between 7:30 a.m. - 4:30 p.m., or visit www.mda.state.md.us.

For information and archived stories on equine WNV, visit www.TheHorse.com/wnv.


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