Tests had already detected EEE in mosquitoes taken in Whiting in southern Addison County.
The mosquitoes that most recently tested positive were collected on Monday.
The virus also was found in two additional pools collected on Aug. 14 and Sunday from the same area of Whiting where mosquitoes had already tested positive.
Tests have also found West Nile virus in the area.
On Thursday evening, the Agency of Agriculture sprayed pesticide over a 2-mile radius centered on a swampy area of Whiting.
Last year two men died after contracting EEE and the Health Department continues to urge everyone to avoid mosquito bites.