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Mosquito Advisory: No Positive EEE or West Nile Virus Findings Reported July 16, 2021

PROVIDENCE The Rhode Island Department of Environmental Management (DEM) today announced that all 178 mosquito samples from 57 traps set statewide between June 23 and July 6 have tested negative for both West Nile Virus (WNV) and Eastern Equine Encephalitis (EEE) by the Rhode Island Department of Health (RIDOH). Results are pending for the pools, or samples, collected during the July 7-15 period.

There have been no findings of EEE or WNV in mosquito samples to date in Rhode Island this year, nor has EEE been detected in pools from either Connecticut or Massachusetts to date. There is WNV activity regionally, with two detections in Connecticut (one each in the central and western parts of the state) and 12 WNV-positive pools collected in Massachusetts (10 in Middlesex County and one each in Suffolk and Barnstable Counties). These findings are not unexpected, as WNV has become established in North America following its introduction in 1999. The positive findings in neighboring states indicate that WNV is beginning seasonal activity in our area. WNV will become more prevalent as the season progresses, so residents are advised to reduce their exposure to mosquitoes until the first hard frost.

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. DEM and RIDOH remind the public to eliminate mosquito breeding grounds and prevent being bitten, whenever possible. The two agencies emphasize that if Rhode Islanders are going to be outside during the peak "biting hours" at dawn and dusk to wear 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.

- Consider restricting outdoor activities during dawn and dusk, periods when mosquito biting activity is more prevalent. Dress appropriately (wear long-sleeved shirts and long pants) and use mosquito repellent if outdoors during these times.

- 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.

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 July through September, with additional reports as necessary. Typically, positive test results trigger additional trapping to assess risk.

Related links

  • Department or agency: Department of Environmental Management
  • Online:
  • Release date: 07-16-2021

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