Health officials have detected West Nile Virus in mosquitoes collected from Lexington, Belmont and Waltham last week.
The state Department of Public Health has announced the detection of the virus in mosquitoes collected from the towns on Tuesday, Aug. 7.
The virus had been found in several other nearby communities, including Arlington and Medford, in July, according to the state.
The mosquito-borne virus can cause encephalitis, or swelling of the brain, and can be transmitted to humans through a bite of an infected mosquito.
The Health Division of Lexington’s Office of Community Development issued an alert about the discovery of the virus Friday. The town had begun treating catch basins with larvicide earlier this month in an effort to reduce mosquito populations.
Lexington health officials will continue that work and will be investigating sources of potential breeding grounds for mosquitoes.
Health officials in Lexington reminded residents to avoid mosquito bites and to apply insect repellent when going outdoors.