The town says the risk level for the virus is still low, but that people should still be taking precautions against getting bitten.
The Department of Health is applying larvicide to catch basins and some wetlands as it keeps testing for the virus.
Mosquitos get the illness by biting infected birds, and state officials first detected the virus in mosquitos this year in Easton. Most people infected with West Nile have no symptoms, but in rare cases the disease can become serious.
Brookline is advising residents to use an insect repellent with DEET or lemon eucalyptus oil, and wear long sleeves outside. Dawn and dusk are the peak hours for mosquito activity.
WBZ's Jim MacKay (@JimMacKayOnAir) has more: