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Saturday, September 3, 2022

Health Department's second finding of West Nile Virus in Westerly

Cautions Public to Prevent Mosquito Bites

The Department of Environmental Management (DEM) today announced that the most recent round of mosquito testing by Rhode Island Department of Health (RIDOH) State Health Laboratories has confirmed a second detection of West Nile Virus (WNV) in the state this summer. As was the case with the first WNV finding, which DEM announced Aug. 17, the second sample also was collected in Westerly. RIDOH testing revealed no new positives of Eastern Equine Encephalitis (EEE). DEM collected 83 samples of mosquitoes from 37 traps set statewide during the week of Aug. 23. Results from mosquitoes collected during the week of Aug. 29 are pending.

Although WNV has now been detected twice from the same Westerly trap site, state officials stress that at this stage of mosquito season, the disease is much more prevalent than EEE and is likely prevalent in mosquitoes statewide. 

WNV is the leading cause of mosquito-borne disease in the continental United States. Cases of WNV occur during mosquito season, which starts in the summer and continues through fall. There are no vaccines to prevent or medications to treat WNV in people. 

Fortunately, most people infected with WNV do not feel sick. About one in five people who are infected develop a fever and other symptoms. About one out of 150 infected people develop a serious, sometimes fatal, illness. 

You can reduce your risk of WNV by using insect repellent and wearing long-sleeved shirts and long pants to prevent mosquito bites. DEM and the RIDOH advise Rhode Islanders 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.

EDITOR'S NOTE: Please read this warning about pesticide use to ward off mosquitos:

To date, Connecticut has reported 151 positive WNV samples but no WNV human or animal cases, and no EEE in mosquitoes, humans, or animals. Massachusetts reports 64 positive WNV samples and one human case and no EEE in mosquitoes, humans, or animals.

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. The following precautions are advised.

Protect yourself

·         Put screens on windows and doors. Fix screens that are loose or have holes.

·         At sunrise and sundown (when mosquitoes that carry EEE are most active), consider rescheduling outdoor activities that occur during evening or early morning. If you must be outside, wear long-sleeved shirts and long pants and use bug spray.

·         Use EPA-approved bug spray with one of the following active ingredients: DEET (20-30% strength); picaridin, IR3535; and oil of lemon eucalyptus or paramenthane. Always read the label and follow all directions and precautions.

·         Do not use bug spray with DEET on infants under two months of age. Children should be careful not to rub their eyes after bug spray has been applied on their skin. Wash children’s hands with soap and water to remove any bug spray when they return indoors.

·         Put mosquito netting over playpens and baby carriages.

Remove mosquito breeding grounds

·         Remove items around your house and yard that collect water. Just one cup of water can produce hundreds of mosquitoes; an unused tire containing water can produce thousands of mosquitoes.

·         Clean your gutters and downspouts so that they can drain properly.

·         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.

·         Remove or treat any shallow water that can accumulate on top of a pool cover. Larvicide treatments, such as Mosquito Dunks can be applied to kill immature mosquitoes. This environmentally friendly product is available at many hardware and garden stores and online.

·         Clean and change water in birdbaths at least once a week.

Best practices for horse owners

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

For more information on DEM programs and initiatives, visit Follow DEM on Facebook, Twitter (@RhodeIslandDEM), or Instagram (@rhodeisland.dem) for timely updates.