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News Release
RI Department of Environmental Management
235 Promenade Street, Providence, RI 02908
(401) 222-2771 TDD/(401) 222-4462

For Release: October 10,2006
Contact: Gail Mastrati 222-4700 ext. 2402
Stephanie Powell 222-4700 ext. 4418

Mosquito Numbers Down Statewide, but Still Infected Mosquitoes in Environment

PROVIDENCE - The Department of Environmental Management announces that test results from two mosquito pools, or samples, from one trap set along Route 78 in Chapmans Swamp in Westerly have been confirmed positive for Eastern Equine Encephalitis. The positive findings came from mosquitoes trapped by DEM staff on October 3 and tested at the RI Department of Health (HEALTH) laboratory. The results were confirmed by HEALTH this afternoon.

One pool was from an Aedes species that is a mammal-biter; the other, was from a Culex species that prefers biting birds and rarely bites humans. It is the second time that EEE has been found in the Chapmans Swamp area this season, though not at the same trap site.

According to Alan Gettman, Ph.D., DEM's mosquito abatement coordinator, it is not surprising to find EEE in Chapmans Swamp at this time of year. It is in a location where infected mosquitoes have been found in past years toward the end of the mosquito season, and in an area where an intense trapping effort has been underway.

The mosquito population has declined significantly, biting activity is much lower, and no new mosquitoes are being produced. However, there will be some mosquito activity, particularly during periods of warmer daytime temperatures, until the first hard frost.

Gettman re-iterated today that Rhode Islanders should continue to protect themselves from mosquito bites, by covering up and wearing mosquito repellent when mosquitoes are active. One prime example, he noted, would be when people are hiking in the woods in warmer weather.

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, 10 mosquito pools have tested positive for West Nile Virus, and three mosquito pools have tested positive for EEE. West Nile Virus is well-established throughout the state and, indeed, throughout the country, and EEE has been found inmost areas of Rhode Island in prior years. The unusually high number of mosquitoes testing positive for Eastern Equine Encephalitis in Southeastern Massachusetts suggests that the Rhode Island area this year has been at a higher than normal risk for EEE, according to DEM officials.

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, generally by Wednesday, with additional reports as necessary.

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".


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