Rhode Island Mosquito Sample Tests Positive For Eastern Equine Encephalitis

The Rhode Island Department of Environmental Management (DEM) and the Rhode Island Department of Health (RIDOH) today announced a mosquito sample collected on August 1 in Chapman Swamp in Westerly has tested positive for Eastern Equine Encephalitis (EEE). This is the first finding of EEE in Rhode Island this year and is not unexpected. The positive mosquito pool is a species that primarily bites birds; this species is largely responsible for maintaining the virus in the bird population. There are no confirmed human cases of EEE in Rhode Island.

In addition to EEE, Rhode Island tests mosquitos for West Nile Virus (WNV). To date, there has been one confirmed local finding of WNV in a mosquito sample. There are no confirmed human cases of WNV in Rhode Island. WNV has also been detected in mosquito samples trapped in Massachusetts and Connecticut. EEE has also been confirmed in a mosquito sample trapped in southeastern Massachusetts. And a pool of mosquitoes trapped on August 1 in Tiverton, Rhode Island has tested positive for Jamestown Canyon Virus (JCV). JCV rarely causes human illness.

Mosquito-borne diseases are more prevalent in late summer and early fall, and risk typically lasts until the first frost. Personal protection is the most effective way to guard against mosquitoes that may carry WNV, EEE, or other diseases. Throughout the mosquito season, the public is reminded to:

• Eliminate mosquito breeding grounds from yards by removing anything that holds standing water, such as old tires, buckets, junk and debris. Just one cup of standing water can produce hundreds of mosquitoes. • Clean gutters so they drain correctly. • Make sure swimming pools are treated with chlorine, pumps are running properly, and any water that collects on pool covers is removed. • Avoid mosquito bites by using screens on windows and doors, covering up at dawn and dusk, and putting mosquito netting over playpens and baby carriages when they are outside. Use mosquito repellent with at least 20 percent DEET but no more than 30 percent. Do not use repellent on infants.

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, depression, 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.

Mosquitoes are trapped weekly by DEM and tested at the Rhode Island State Health Laboratories. DEM issues weekly advisories on test results from late June through September, with additional reports as necessary. Test results are pending for the remaining 168 traps set on August 1 and will be included in next week’s announcement. Typically positive test results trigger additional trapping to assess risk; today’s finding will result in additional trapping in the Westerly area where the positive mosquito sample was found.

Visit www.health.ri.gov for additional mosquito prevention tips and for local data. For more information about DEM divisions and programs, visit www.dem.ri.gov