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The Rhode Island Department of Environmental Management (DEM) and Rhode Island Department of Health (RIDOH) today announce the detection of the first mosquito sample of 2020 that has tested positive for Eastern Equine Encephalitis (EEE).

The pool producing the sample consisted of 50 individual members of Culiseta melanura, a species of mosquitoes that bites birds almost exclusively. They were trapped August 11 in Chapman Swamp, in Westerly, where mosquitoes carrying the EEE virus have previously been found in 1996, 2003, 2013, 2016, and 2019. The other 102 pools collected August 11 all tested negative for EEE and West Nile Virus (WNV).

All 162 pools from 38 traps set statewide August 3 and August 5 confirmed negative for both EEE and WNV. Results from 147 pools collected from 44 traps on August 17 are pending. To date, Massachusetts has confirmed 3 human cases of EEE and no findings of WNV. The Connecticut Department of Public Health announced Connecticut’s first EEE-positive mosquitoes August 11 in nearby Stonington and first human case of WNV August 17.

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 EEE established in Rhode Island and WNV nearby, DEM and RIDOH remind the public to eliminate mosquito breeding grounds and prevent being bitten, whenever possible. While outdoor spaces reduce the likelihood of exposure to COVID-19, they pose a greater risk of exposure to mosquito-borne diseases. For this reason, DEM and RIDOH emphasize that if Rhode Islanders are going to be outside during the peak “biting hours” – at dawn and dusk – to wear your face masks, long sleeves and pants, and use insect repellent. 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.

Get rid of mosquito breeding grounds

  • Get rid of anything around your house and yard that collects 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 on-line.
  • Change the water in birdbaths at least two times a week and rinse out birdbaths 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.