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State Mosquito Advisory for Monday, September 23: No spraying tonight. Next Update: Tuesday, Sept. 24, at 4 PM

PROVIDENCE The second round of aerial mosquito treatments that state officials announced last week will likely begin either Tuesday night or Wednesday night this week, depending on weather conditions. The Department of Environmental Management (DEM) and the Rhode Island Department of Health (RIDOH) will provide an update on the spraying schedule tomorrow.

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. More information on health and spraying is available here. For FAQs on the impact of spraying on pets and livestock, click here. Rhode Islanders may call 2-1-1 for more information.

The two areas to be sprayed include one surrounding West Warwick and one in the southwest part of Rhode Island. 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.

A map of the two areas to be sprayed is attached. This map also includes the areas previously sprayed between September 8 and September 10. All these areas are still considered critical risk areas for EEE.

Aerial spraying depends on calm conditions and temperatures above 58 degrees and timing is always subject to change. This includes the updated estimate on a Tuesday or Wednesday start date. Spraying here will begin as soon as the aviation company that the state has contracted with can return to Rhode Island after completing in-progress work in Massachusetts and the weather is suitable for spraying operations here. Tonight's forecast calls for rain and winds up to 15 to 20 MPH, which means the flight crew might not finish spraying Massachusetts tonight and will likely finish tomorrow night. This would result in spraying beginning in Rhode Island on Wednesday.

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.

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. 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.

In the latest round of trapping, RIDOH's State Health Laboratories tested 123 pools, or samples, that DEM collected from 40 traps set September 16 and 17, finding all samples negative for EEE but two positive detections for West Nile Virus (WNV), one each in Tiverton and Westerly. These are the state's third and fourth WNV detections in 2019.

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.

Related links

  • Department or agency: Department of Environmental Management
  • Online: http://www.dem.ri.gov/
  • Release date: 09-23-2019

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