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Saturday, October 16, 2021

DEM finds more West Nile Virus

Urges Residents to Prevent Mosquito Bites until First Hard Frost

The Department of Environmental Management (DEM) today announced that the most recent round of testing by the Rhode Island Department of Health (RIDOH) State Health Laboratories has confirmed one new positive finding of West Nile Virus (WNV).

The finding was detected in a mosquito sample collected in Glocester on Sept. 27.

DEM collected 210 samples of mosquitoes from 39 traps set statewide Sept. 21-28. Results from mosquitoes collected during the Sept. 29-Oct. 12 period are pending. To date, the state has confirmed six positive WNV findings, but no mosquito samples have tested positive for Eastern Equine Encephalitis (EEE).

Along with the human case of WNV announced by RIDOH Oct. 7 and the positive finding of EEE confirmed in Connecticut Oct. 1, today's announcement is a reminder that Rhode Island residents should take extra precautions to avoid being bitten during the final few weeks of the mosquito season.

DEM and RIDOH advise residents to reduce their exposure to mosquitoes until the first hard frost. (A hard frost is when the air and the ground freeze below 32°F for three hours or below 28°F for two hours.)

WNV is much more prevalent than EEE. It has become established in North America following its introduction in 1999. To date this mosquito season, 207 pools of mosquitoes trapped in Connecticut and 144 mosquito pools in Massachusetts have tested positive for WNV.

Connecticut has confirmed three WNV cases in humans and Massachusetts has confirmed eight human cases and one alpaca case. Connecticut also has confirmed two positive EEE findings in mosquito samples.

Personal protection is the first line of defense against mosquitoes that may carry WNV, EEE, or other diseases – and the most effective way to avoid infection. With WNV established in the state, residents are reminded to eliminate mosquito breeding grounds and prevent being bitten, whenever possible.

Visit for additional mosquito prevention tips, videos, and local data. DEM and RIDOH also remind Rhode Islanders to take precautions to avoid mosquito bites when traveling to Zika-affected countries. Pregnant women and women who are considering becoming pregnant should not travel to countries with active transmission of Zika.

Mosquitoes are trapped weekly by DEM and tested at the RIDOH State Health Laboratories. DEM issues advisories on test results from July through mid-October, with additional reports as necessary. Typically, positive test results trigger additional trapping to assess risk.

For more information about DEM divisions and programs, visit or follow us on Facebook or Twitter (@RhodeIslandDEM).

Related links

DEET Fact Sheet

Mosquito Dunks

Mosquito Prevention Tips