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Final Weekly Mosquito Advisory

PROVIDENCE The Rhode Island Department of Environmental Management (DEM) today announced test results for the final set of mosquito samples this season. Thirty mosquito samples from 27 traps set on Monday, September 24 have tested negative for both West Nile Virus (WNV) and Eastern Equine Encephalitis (EEE). Testing is being suspended in light of the cooler temperatures and the related drop in mosquito populations statewide.

While mosquito numbers are lower, Rhode Island has not yet experienced a hard frost which eliminates the risk of contracting mosquito-borne diseases. People may still see an occasional mosquito, particularly on warmer days and nights, and should continue to protect themselves against bites.

This year, in Rhode Island, 10 mosquito samples from seven communities (Central Falls, Cranston, Pawtucket, Providence, South Kingstown, Tiverton and Warren) tested positive for WNV, and four mosquito samples have tested positive for EEE. Connecticut and Massachusetts continue to report positive findings of WNV in mosquito samples. Positive findings of WNV in Southern New England have been higher this year than recent years. This week, four EEE-positive mosquito samples were confirmed in two towns in eastern Connecticut, indicating that EEE is circulating in the regional environment.

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 and EEE established throughout the state, DEM and the Rhode Island Department of Health (RIDOH) remind the public to eliminate mosquito breeding grounds and prevent being bitten, whenever possible. The following precautions are advised:

Use EPA-approved bug spray with one of the following active ingredients: DEET (20-30% strength is recommended), picaridin, IR3535, and oil of lemon eucalyptus or para-menthane-diol. Minimize outdoor activity at dawn and at dusk when mosquitoes are most active. Put insect netting over strollers and playpens. Wear long sleeves and long pants whenever possible, particularly if you are outdoors during dawn and dusk. Remove anything around your house and yard that collects water; just one cup of water can produce hundreds of mosquitoes. Clean gutters and downspouts to ensure proper drainage, and repair holes in window screens. Remove any water from unused swimming pools, wading pools, boats, planters, trash and recycling bins, tires, and anything else that collects water, and cover them. Change the water in birdbaths at least two times a week, and rinse out birdbaths once a week.

Horses are particularly susceptible to WNV and EEE. Horse owners are advised to vaccinate their animals early in the season and practice the following:

Remove or cover areas where standing water can collect. Avoid putting animals outside at dawn, dusk, or during the night when mosquitoes are most active. Insect-proof facilities where possible and use approved repellants frequently. Monitor animals for symptoms of fever and/or neurological signs (such as stumbling, moodiness, loss of appetite) and report all suspicious cases to a veterinarian immediately. If you are unsure if your horse is properly vaccinated you should consult with your veterinarian.

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. Last year, the RIDOH State Health Laboratories changed their testing methodology to use a more sensitive testing method which may account for an increase in positive results going forward. DEM issues advisories on test results from late June through September, with additional reports as necessary. Trapping concluded for the season on September 24.

For more information about DEM divisions and programs, visit Follow us on Facebook at or on Twitter (@RhodeIslandDEM) for timely updates.

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  • Department or agency: Department of Environmental Management
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  • Release date: 10-05-2018

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