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Wednesday, August 15, 2012

DEM has found EEE and West Nile virus in Rhode Island samples

DEM announces EEE found in mosquitoes trapped in Tiverton
RI DEM News Release

PROVIDENCE - The Department of Environmental Management announces that test results from one mosquito pool, or sample, from a trap set in central Tiverton has been confirmed positive for Eastern Equine Encephalitis (EEE). 

It is the first time this year that EEE has been positively identified in Rhode Island, although it is presumed likely to be present in other areas of the state. The positive EEE result was from a Culiseta species that feeds almost exclusively on birds.

The positive finding came from mosquitoes trapped by DEM staff on August 6 and tested at the RI Department of Health (HEALTH) laboratory. The results were confirmed today. As a result, DEM will be setting extra mosquito traps in the East Bay area.

In Rhode Island EEE has only been found in mosquito species that bite birds, unlike Massachusetts, where EEE has been isolated in mammal-biting mosquito species trapped in numerous locations in southeastern Massachusetts. These findings of significant numbers of mosquitoes carrying EEE in mammal-biting mosquitoes in Massachusetts prompted aerial spraying in affected Massachusetts communities.

According to Alan Gettman, Ph.D., DEM's mosquito abatement coordinator, it was not surprising to find the positive EEE sample at this time of year. The positive result is confirmation that there are infected mosquitoes in the environment. Therefore, all Rhode Islanders should take extra care to protect themselves, particularly when mosquito-biting activity is high.

Biting activity depends on several conditions. It generally is greatest from dusk to dawn. During the day it decreases in sunny areas at lower temperatures and increases in shady areas at higher temperatures. Biting activity also generally increases with high humidity and with low wind.

Personal protection is the first line of defense against mosquitoes that can carry diseases such as West Nile Virus and EEE and is by far the most effective way of avoiding infection. People should routinely use mosquito repellent and cover up when mosquito-biting activity is greatest. They should place mosquito netting over playpens and carriages outside, and be sure that screens are in good repair. Mosquito repellent should contain no more than 30 percent DEET, and it should not be used on infants.

This year, to date in Rhode Island, two pools of mosquitoes has tested positive for West Nile Virus and one pool has tested positive for Eastern Equine Encephalitis.

Mosquitoes in Rhode Island are trapped every week statewide by DEM staff and tested at the RI Department of Health laboratory. DEM will normally report mosquito test results once a week on a routine basis, with additional reports as necessary. Routine test results from remaining pools of mosquitoes trapped during the week of August 6 will be included in next week's announcement.

For online information about mosquito-borne diseases, go to DEM's website,, and click on "Public Health Updates", or go to the HEALTH website,, and click on "E" (Eastern Equine Encephalitis) or "W" (West Nile Virus) under "Health Topics".