Protect yourself from mosquito borne illnesses. (updated 9/20/19)

UPDATE 9/19/19


With areas of Rhode Island still at critical risk for the EEE virus, parts of 12 communities are expected to be aerially treated with mosquito pesticide next week

PROVIDENCE – 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 inCoventry 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 is available here.  



Aerial spraying in northern Rhode Island (parts of Burrillville, North Smithfield, and Woonsocket) was not completed last night due to falling temperatures. Spraying in these areas, and parts of southern Rhode Island (including parts of Westerly, Hopkinton, and Charlestown) is planned for tonight. Spraying will start at dusk tonight and will be completed by 4:30 am Tuesday morning. We will provide more details on the timing when the flight plan is finalized just before take-off.

While spraying is occurring, it is best to err on the side of caution and limit time outdoors and keep your windows closed. The product being sprayed is being used at very low concentrations. No adverse health risks are expected with its use for mosquito control. However, it is generally good for people to limit their exposure to pesticides.

On Sunday night and early Monday morning, spraying was done in all of West Warwick and parts of Coventry, Cranston, Warwick, East Greenwich, and West Greenwich, as well as all of Central Falls, Pawtucket, and North Providence and parts of Providence, East Providence, Smithfield, Lincoln, and Cumberland.


Aerial spraying to protect humans from EEE infection will touch parts of 21 communities encompassing a total approximate area of 110,000 acres.


Sometimes the state and/or local communities ground or aerial spray pesticide to control mosquitoes in a variety of environments such as outdoor residential and recreational areas, commercial urban areas, and rural areas. Mosquitoes are a nuisance that impact quality of life, and they also can carry diseases, such as Eastern Equine Encephalitis (EEE) or West Nile Virus (WNV).

When is aerial spraying of insecticides considered?

In situations where there is an elevated risk of human disease, state or local officials may consider the use of an aerial pesticide spray in the evening and overnight hours to reduce the number of infected, adult mosquitoes in the specific areas of elevated risk. Many breeding areas of high concern are not accessible by truck-mounted ground sprayers. It should be noted that although the aerial spraying is considered necessary to reduce human risk, it will not eliminate risk. It is critical that residents protect themselves from mosquito bites by staying indoors during peak mosquito hours, applying insect repellent when outdoors, draining standing water where mosquitoes breed, repairing screens, and protecting animals and pets.

Why is my location not in the spray area?

The spray area is designed to target areas that mosquito-borne disease activity originates from. There are several possible reasons why your location may not be in the current spray area, the most common being that you are not located in an area that has been determined to have a risk of mosquito-borne virus amplification sufficient to warrant spraying.

More information is available on the RIDEM website.  

August 26, 2019

 Back to School Health Alert: 'Smart Scheduling' and Mosquito and Tick-Borne Disease Prevention Resources

Back-to-School time coincides with the time of year that the risk of mosquito-borne diseases, like Eastern Equine Encephalitis (EEE) and West Nile Virus (WNV), peaks in Rhode Island. The mosquitoes that carry these diseases bite until the first frost (usually around the end of October). 

To date, in Rhode Island, there have been two findings of EEE (in Central Falls) and no findings of WNV in mosquito samples. The 330 positive EEE mosquito pools in Massachusetts, coupled with multiple findings of both EEE and WNV in mosquitoes from eastern Connecticut, however, clearly indicate this remains a higher-than-average risk summer for mosquito-borne diseases in southeastern New England. Massachusetts has announced four human cases of EEE, including one death. Also, two horses, one from Mendon and another from Uxbridge, have tested positive for EEE.

The Rhode Island Department of Health (RIDOH) recommends “smart scheduling” whenever possible as a precaution against seasonal mosquito-borne illness. These recommendations should be considered when planning all back-to-school outdoor activities, including games and practices for all sports. Mosquito-borne diseases are more prevalent in late summer and early fall until the first hard frost eliminates the season’s mosquitoes.

Whenever possible, avoid scheduling games and practices during early morning or dusk hours, or relocate activities to an indoor venue during these times. This will help minimize the risk of mosquito bites for players, coaches, and spectators alike — which may include individuals more vulnerable to severe illness, such as the elderly and people with weakened immune systems.

At a minimum, RIDOH recommends that schools and organizations remind all participants in outdoor activities to protect themselves from mosquito bites. They should:

  • Avoid outdoor activities during dawn and dusk. Mosquitoes are most active at this time.
  • Wear an insect repellent with no more than 30 percent DEET — if they must be outside at dawn or dusk: (Insect Repellent Essentials: A Brief Guide)
  • Wear long-sleeve shirts and long pants when possible to avoid exposing skin to mosquitoes.
Please download and post this poster from RIDOH and the Rhode Island Department of Environmental Management advising people of the higher than usual EEE activity and ways to prevent mosquito-borne disease. RIDOH also has informational flyers with mosquito bite prevention tips that you may wish to post, or send home in student backpacks: "Preventing Mosquito Bites," "Help Control Mosquito Breeding Grounds and Prevent Mosquito Bites" (Also in Spanish), and "Everything You Need to Know About Mosquitoes and Ticks."

We also ask that facility staff be reminded to remove or cover anything around school grounds and athletic fields that might allow water to collect (for example, bird baths), or frequently empty anything that collects standing water. Just one cup of water can become a breeding ground for hundreds of mosquitoes.

Over the coming weeks and months, RIDOH will continue to update school departments whenever conditions change. In the event that a greater threat of mosquito-borne disease is observed, public health officials may advise all schools and leagues to reschedule events and/or offer additional recommendations. 

If you need additional information about smart scheduling or about personal protection from mosquito bites, please contact RIDOH's Health Information Line at 401-222-5960.