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DEM, RI DOH Report Second West Nile Virus Finding

Test Results Not Unexpected, but Serve as Reminder for Public to Protect Themselves Against Mosquito Bites

PROVIDENCE - The Department of Environmental Management (DEM) and the Rhode Island Department of Health (RI DOH) announce that a sample of mosquitoes collected on September 8 in southern Tiverton has tested positive for West Nile Virus (WNV). Samples are tested weekly at the Rhode Island State Health Laboratories. The positive mosquito pool is a species that can bite both birds and humans.

The positive finding is not unexpected. West Nile Virus is increasingly being detected in mosquito samples trapped in neighboring states. Mosquito-borne diseases are more prevalent in late summer and early fall, and risk typically lasts until the first frost.

Also, test results from a mosquito pool, or sample, from a trap set in the northern part of Tiverton has been confirmed positive for Highlands J Virus. The positive Highlands J result was from a species of mosquitoes that bites birds and humans. Highlands J virus is a bird disease that does not affect humans, but which is an indicator that environmental conditions are appropriate for the transmission of other mosquito-borne viruses.

However, there have been no reports of Eastern Equine Encephalitis (EEE) in Rhode Island or in the neighboring states of Massachusetts or Connecticut so far this season.

"These positive findings are clear evidence that mosquito-borne virus is circulating in the environment," said DEM Director Janet Coit. "From now until the end of the mosquito season, Rhode Islanders should redouble efforts to protect themselves from exposure to WNV and EEE by using mosquito repellent and eliminating mosquito breeding grounds."

"Although these findings are normal for this time of year, all Rhode Islanders should take certain precautions to protect themselves and their families from mosquito bites," said Director of Health Nicole Alexander-Scott, MD, MPH. "Personal protection is vital when people are outdoors. Wear long-sleeved shirts and pants, and make sure that all window and door screens are repaired. Additionally, people should minimize outdoor activities at sunrise and sundown, when mosquitoes are most active."

Throughout the mosquito season, residents are encouraged to protect themselves and their families by eliminating mosquito breeding grounds and avoiding mosquito bites. Rhode Islanders should:

Dress for protection. Wear long pants, long-sleeve shirts and socks during outdoor evening activities.

Use bug spray. Use mosquito and tick repellent with no more than 30 percent DEET during outdoor activities, particularly at dusk and during evening hours, when mosquitoes are most active. Do not use repellent on infants.

Time activities for maximum protection. If possible, minimize outdoor activities between dusk and dawn.

Evaluate the environment. Be sure all open windows are screened, repair any holes in screens, and fix loose screens. Remove any standing water around yards and houses by emptying planters, wading pools, trash and recycling bins, and other places where water might accumulate to reduce mosquito breeding. Mosquitoes breed in standing water. Just one cup of standing water can produce hundreds of mosquitoes.

Late summer and early fall are considered high-risk seasons for the transmission of both WNV and EEE to horses by infected mosquitoes. Rhode Island State Veterinarian Scott Marshall, DVM has issued several recommendations to horse owners to help protect their animals from getting bitten by mosquitoes. He advises horse owners to use repellents on their animals; consider stabling their horses indoors at dawn and dusk, which are considered heavy mosquito feeding times; remove free standing water from stable areas; and consult with their veterinarian to determine whether their horses are properly immunized, as vaccination is safe and effective in the prevention of EEE in horses. A vaccination for horses is also available for WNV.

Mosquitoes are trapped every week statewide by DEM staff and tested at the Rhode Island State Health Laboratories. DEM will normally report mosquito test results once a week on a routine basis from late June through September, with additional reports as necessary. Test results from the remaining pools of mosquitoes trapped on September 8 will be included in next week's announcement. Positive mosquito test results will generally trigger additional trapping to assess risk.

Visit HEALTH's website for additional prevention tips and for Rhode Island-specific data.

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  • Department or agency: Department of Environmental Management
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  • Release date: 09-15-2015

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