As a part of continued work to protect public health by minimizing Rhode Islanders’ exposure to mosquitoes that could be carrying Eastern Equine Encephalitis (EEE), the Rhode Island Department of Environmental Management (DEM) and the Rhode Island Department of Health (RIDOH) announced today that they will be coordinating a second round of aerial mosquito spraying in two areas next week. Weather permitting, state officials are estimating that the next round of spraying could occur on the night of Monday, September 23. The areas to be sprayed have been identified using several factors, including information about new human cases of EEE, cases of EEE in non-human mammals, positive mosquito samples in Rhode Island and in neighboring states, and information about the habitats in which mosquitoes most readily breed.
The two areas to be sprayed include one surrounding West Warwick and one in the southwest part of Rhode Island. A map of the two areas to be sprayed is attached. All four of the areas that already were sprayed September 8-10, however, are considered “critical risk” areas for EEE.
The area surrounding West Warwick includes all West Warwick and parts of Cranston, Warwick, East Greenwich, West Greenwich, Coventry, and Scituate. Some of this area was previously sprayed on September 9, but officials have expanded this zone westward to Route 102 in Coventry and both westward and southward in West Greenwich.
The southwest area to be sprayed includes much of Westerly and parts of Hopkinton and Charlestown that were already sprayed on September 10. This expanded area of critical risk now also encompasses new swaths of Hopkinton, Richmond, and Charlestown as well as the southwestern section of South Kingstown.
Since four areas of Rhode Island were aerially sprayed with pesticide between September 8 and September 10, two additional human cases of EEE have been diagnosed in Rhode Island. One individual lives in Coventry and one lives in Charlestown. Both have been discharged from the hospital and are recovering. A third person from West Warwick who was diagnosed with EEE in 2019 passed away.
This has been a year with significantly elevated EEE activity in Rhode Island and southeastern New England. This week RIDOH’s State Health Laboratories have identified EEE in a mosquito pool from western Coventry. EEE has been detected by RIDOH’s State Health Laboratories in seven mosquito pools to date: two from Central Falls, three from Westerly, one from Block Island, and one from western Coventry. Additionally, one horse from Westerly has tested positive for EEE and RIDOH and DEM have previously announced that three deer have tested positive for EEE (one in Coventry, one in Richmond, and one in Exeter). Deer, like horses, cannot transmit EEE to humans. However, they are an indication that infected mosquitoes are present in the area and people need to continue to take precautions.
Officials at DEM and RIDOH have identified these areas for additional spraying in close consultation with entomologists on the Rhode Island Mosquito-Borne Disease Advisory Group. Aerial spraying depends on calm conditions and temperatures above 58 degrees.
Spraying will not occur over fish hatcheries, certified organic farms, surface drinking water supplies, or other open water bodies and coastal areas. The state will use the same pesticide, Anvil 10+10, that it used in its previous adulticiding operations September 8-10. It will be applied at the same low concentration by the same company as the last time. In its first round of spraying, the state treated 115,179 total acres. Approximately 6/10 of an ounce, aerosolized, was used to treat each acre (slightly less than four teaspoons per acre). The Commonwealth of Massachusetts has used this same pesticide when spraying this year.
No adverse health risks are expected with this product’s use for mosquito control. However, it is generally good for people to limit their exposure to pesticides. While spraying is occurring, it is best to err on the side of caution and limit time outdoors and keep windows closed. DEM and RIDOH will work with the Rhode Island Emergency Management Agency to urge the 12 affected communities to activate “code red” alerts to update residents with this information, and additional information about spraying.
EEE is a rare but serious illness that occurs when people are bitten by infected mosquitoes. It can affect people of all ages. Aerial spraying is only one tool used to combat risk from mosquito-borne disease. The foundation of all risk reduction remains personal protection (mosquito repellent, long sleeves and pants, avoiding outdoor activities between dusk and dawn, repairing window and door screens, and dumping standing water). If possible, people should limit their time outdoors at sunrise and sunset. If they are going to be out, people should wear long sleeves and pants and use bug spray. Aerial spraying effectively reduces the risk of mosquito-borne disease but if does not eliminate the risk completely. In addition, fewer mosquitoes are active as evening temperatures get cooler, but those mosquitoes that are active are more likely to be infected with EEE.
The risk from mosquito-borne disease will continue until the first hard frost. However, mosquito spraying efficacy substantially decreases once nighttime temperatures fall below 60 degrees and cannot occur once temperatures fall below 50 degrees. More information on health and spraying is available here. For FAQs on the impact of spraying on pets and livestock, click here.
