West Nile virus has been found in mosquitoes collected at Aberdeen Proving Ground, preventive medical specialists on the base reported Friday.
The state Department of Health and Mental Hygiene sent pest control workers to apply insecticide in the area.
The infected mosquitoes were trapped at one of 12 sites on the base, the Army said. Army officials said they would increase the number of trapping sites on the installation and would also increase surveillance of dead birds.
Surveillance for West Nile virus at Aberdeen Proving Ground started in late April. From a total of 798 pools of mosquitoes tested for the virus, one has tested positive to date, officials said. A pool can range from one mosquito to 25.
According to Lt. Col. John M. Wempe, commander of the Kirk Army Health Clinic, three pools of mosquitoes have previously tested positive for West Nile virus in Maryland this year: one in the Curtis Bay area of Anne Arundel County July 1, one in the West Lanham Hills area of Prince George's County on July 10, and the third from the White Marsh are of Baltimore County on July 17.