Mosquito Advisory: State Announces New Findings on West Nile Virus


PROVIDENCE – The Department of Environmental Management (DEM) announced today that the latest round of testing by RIDOH State Health Laboratories has confirmed a new positive isolation (finding) of West Nile Virus (WNV) released from a trap on Aug. 30 was collected in Johnston. DEM collected 82 pools (samples) of mosquitoes from 23 traps set across the country from August 26th to 30th. Results for mosquitoes caught between August 31 and September 9 are pending. To date, the state has confirmed five positive WNV findings, but no mosquito samples have tested positive for Eastern Equine Encephalitis (EEE).

WNV is much more common than EEE. It established itself in North America after its introduction in 1999. To date, 154 mosquito pools in Connecticut and 108 mosquito pools in Massachusetts have tested positive for WNV this summer. Connecticut has confirmed three WNV cases in humans and Massachusetts has confirmed four human cases and one alpaca case. The positive results in Connecticut, Massachusetts and Rhode Island show that WNV has established seasonal activity in our area. WNV will become more common as the season progresses, so DEM and the Rhode Island Department of Health (RIDOH) advise residents to reduce their exposure to mosquitoes until the first hard frost. No EEE findings were found in mosquito pools in Connecticut, Massachusetts or Rhode Island.

Personal protection is the first line of defense against mosquitos, which can transmit WNV, EEE, or other diseases – and the most effective way to avoid infection. With the establishment of WNV in the state, residents are being reminded to clear mosquito breeding grounds and, if possible, prevent them from being bitten. The following precautions are recommended.

Protect yourself:

– Attach screens to windows and doors. Repair screens that are loose or have holes in them.

– At sunrise and sunset (when mosquitoes that carry EEE are most active) consider postponing outdoor activities that happen in the evening or early morning. If you need to be outside, wear long sleeved shirts and pants, and use bug spray.

– Use an EPA approved bug spray containing any of the following active ingredients: DEET (20-30% starch); Picaridin, IR3535; and lemon eucalyptus or paramenthane oil. Always read the label and follow all directions and precautions.

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

– Place mosquito nets over playpens and strollers.

Get rid of the mosquito breeding grounds

– Eliminate anything around your home and garden that collects water. Just one cup of water can produce hundreds of mosquitoes; An unused tire that contains water can produce thousands of mosquitos.

– Clean your gutters and downspouts so they can drain properly.

– Remove and cover all water from unused swimming pools, paddling pools, boats, planters, garbage and recycling bins, tires, and anything else that collects water.

– Remove or treat shallow water that may collect on a pool cover. Larvicide treatments like mosquito dunks can be used to kill immature mosquitoes. This environmentally friendly product is available in many DIY megastores with gardeners as well as online.

– Change the water in bird baths at least once a week and rinse out bird baths once a week.

Best Practices for Horse Owners:

Horses are particularly susceptible to WNV and EEE. Horse owners are advised to vaccinate their animals at the beginning of the season and to practice the following:

– Remove or cover areas in which standing water can collect.

– Avoid taking animals outside at dawn, dusk or during the night when mosquitoes are most active.

– Use insect-proof equipment and frequently approved repellants as far as possible.

– Monitor the animals for symptoms of fever and / or neurological signs (such as stumbling, moodiness, loss of appetite) and report any suspected cases to a veterinarian immediately. If you are unsure whether your horse is properly vaccinated, you should consult your veterinarian.

Visit health.ri.gov/mosquito for more mosquito prevention tips, videos, and local data. DEM and RIDOH also remind Rhode Islanders to take precautions to avoid mosquito bites when traveling to Zika affected countries. Pregnant women and women considering pregnancy should not travel to countries where Zika is actively transmitted. Mosquitoes are caught weekly by DEM and tested at RIDOH State Health Laboratories. From July to September, DEM publishes notes on test results, with additional reports if necessary. The test results for the traps, which were set nationwide from August 31 to September, are pending. 9 and will be included in future announcements. Typically, positive test results trigger additional catch to assess risk.

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