Final RI Mosquito Report of 2022: No WMV or EEE Detected

Published on Friday, October 14, 2022

PROVIDENCE, RI – The Rhode Island Department of Environmental Management today announced that the final set of mosquito samples tested this season by the Rhode Island Department of Health (RIDOH) State Health Laboratories have confirmed negative for West Nile Virus (WNV) and Eastern Equine Encephalitis (EEE). These results are from the 131 pools collected from 55 traps set during the final two weeks of September. Testing is being suspended for the season because of cooler temperatures and the corresponding drop in mosquito populations statewide. During the 2022 testing season, one EEE detection was made: from a mosquito sample from a trap set in South Kingstown on Aug. 9. Three mosquito samples tested positive for WNV detections during the season: two from Westerly traps set on Aug. 9 and Aug. 23 and one from a trap set in North Kingstown on Sept. 7. During the season, there was one human case of WNV involving a Providence County resident in their 70’s that was reported on September 26 and one human case of Jamestown Canyon Virus involving a Washington County resident in their 50’s reported on August 1. 

Although mosquito numbers are lower, Rhode Island has not yet experienced a hard frost – which eliminates the risk of contracting mosquito-borne diseases. A hard frost is when the air and the ground freeze below 32°F for three hours or below 28°F for two hours. State officials stress that at this stage of mosquito season, WNV is much more prevalent than EEE and is still likely prevalent in mosquitoes statewide. To date, Connecticut has reported 185 positive WNV samples and five WNV human cases and Massachusetts reports 95 positive WNV samples and six human cases. Both Connecticut and Massachusetts have reported no findings of EEE in mosquitoes, humans, or animals.

WNV is the leading cause of mosquito-borne disease in the continental United States. Cases of WNV occur during mosquito season, which starts in the summer and continues through fall. There are no vaccines to prevent or medications to treat WNV in people. Fortunately, most people infected with WNV do not feel sick. About one in five people who are infected develop a fever and other symptoms. About one out of 150 infected people develop a serious, sometimes fatal, illness. You can reduce your risk of WNV by using insect repellent and wearing long-sleeved shirts and long pants to prevent mosquito bites. DEM and RIDOH advise Rhode Islanders to reduce their exposure to mosquitoes until the first hard frost.

Rhode Islanders are reminded that ticks can continue to bite and spread diseases, even in the fall and winter. University of Rhode Island’s Tick Encounter Resource Center advises that most of the ticks this time of year are blacklegged (deer) ticks, which can transmit Lyme and other diseases. In the fall, do quick tick checks at least once or twice a day, especially focusing above the waist, and to remember to tuck in your shirt when outdoors to keep ticks from crawling underneath. Anyone with symptoms of Lyme disease should contact their healthcare provider. For more information and tips on preventing Lyme disease and other tick-borne diseases, please visit http://health.ri.gov/ticks.

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. 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.

Remove mosquito breeding grounds

• Remove items around your house and yard that collect 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 online.
• Clean and change water in birdbaths at least 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 health.ri.gov/mosquito 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 June through early October, with additional reports as necessary. Typically, positive test results trigger additional trapping to assess risk. 

For more information on DEM programs and initiatives, visit www.dem.ri.gov. Follow DEM on Facebook, Twitter (@RhodeIslandDEM), or Instagram (@rhodeisland.dem) for timely updates.