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Mosquito Response Protocol
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RI Department of Environmental Management
235 Promenade Street, Providence, RI 02908
(401) 222-2771 TDD/(401) 222-4462
DEM SAYS THIS YEAR'S MOSQUITO POPULATION IS LARGE DUE TO HEAVY RAINFALL IN JUNEPROVIDENCE - From June to October, the Department of Environmental Management traps mosquitoes on a weekly basis for testing at the RI Department of Health Laboratory to determine the presence of West Nile Virus or Eastern Equine Encephalitis (EEE). Trapping began this year on June 10.
According to DEM's mosquito abatement coordinator Alan Gettman, PhD, last week was the third week of trapping for this season. Dr. Gettman said that more mosquitoes were caught in traps last week than ever before in the past 21 years of mosquito trapping. The huge increase in mosquitoes is due to the substantial rainfall Rhode Island had in June; more than nine inches of rain had fallen by mid-June in the state. The rain filled up all pools in the woods, fields and roadsides, providing prime breeding grounds for mosquitoes. The rain also hatched the eggs that led to the new and expectedly large crop of mosquitoes that are biting now. Given the large number of mosquitoes currently in the environment, there is a great deal of biting activity, and people should protect themselves accordingly.
Dr. Gettman said it is impossible to predict whether this higher number of mosquitoes will increase the possibility of mosquito-borne disease in Rhode Island, which is prevalent later in the season as the mosquitoes get older. So far this year, all mosquitoes tested at the Health Laboratory have been negative for EEE and West Nile Virus. In Massachusetts, however, the first case of West Nile Virus was confirmed positive last Friday from mosquitoes trapped in the town of Whitman.
DEM normally reports mosquito test results once a week on a routine basis, with additional reports as necessary. Positive mosquito test results will generally trigger additional trapping to assess risk.
With West Nile Virus and Eastern Equine Encephalitis (EEE) established throughout the state, DEM and the Department of Health (HEALTH) remind Rhode Islanders that personal protection is the first line of defense against mosquito-borne diseases.
Residents should, as part of their normal seasonal routine, protect themselves from exposure to West Nile Virus and EEE by avoiding mosquito bites and eliminating mosquito breeding grounds. At this time of year, they are urged to get rid of anything in their yards that holds standing water, such as old tires, buckets, junk, and debris, and to make sure their gutters are clean so that they drain properly. Mosquitoes breed in standing water. Just one cup of standing water can produce hundreds of mosquitoes.
Personal protection and larviciding are cornerstones of the state's mosquito response protocol. Aerial or ground spraying will be recommended only when a team of mosquito-control experts determines that the public is at substantial risk of contact by infected mosquitoes.
Because horses are susceptible to West Nile Virus and EEE, Rhode Island horse owners should vaccinate their horses early in the season and take measures to control and prevent mosquito exposure. Those controls should include: removing or covering all areas where standing water can collect; applying mosquito larvicide in appropriate locations; and avoiding turning animals outside at dawn, dusk and during the night when mosquitoes are most active. Horse owners should insect-proof facilities where possible; use approved repellants frequently; monitor animals for symptoms of fever, in-coordination, stumbling and neurological signs; and report all suspicious cases to a veterinarian immediately.