Student News

Mosquito Concern

Steve Berman – August 12, 2019

Dear Deerfield Community,

The Massachusetts Department of Public Health’s mosquito surveillance program recently documented a local mosquito as carrying West Nile Virus (WNV). While news of this sort understandably raises concern, it is not surprising for our area during this time of year and with the recent rainy and humid weather conditions.

During the summer months, West Nile Virus becomes prevalent in the local mosquito population which can bite and transmit the virus to humans and birds. The vast majority of people who contract the virus (approx. 80%) experience no symptoms. Of the remaining 20%, most develop only flu-like symptoms. However, approximately 1 in 150 who contract the virus can develop an infection of the brain called encephalitis which is serious, can be debilitating and, on occasion, may be fatal. Fortunately, despite its prevalence in the local mosquito population, development of encephalitis is very low. For example, between 2000 and 2010 there were only 67 documented cases of West Nile encephalitis in the state of Massachusetts, of which six cases were fatal. There have been no reported human cases of West Nile encephalitis in Massachusetts this year.

The only way to prevent West Nile virus is to avoid mosquito bites by:

  • Wearing an insect repellent (DEET, picardin or oil of lemon eucalyptus for exposed skin; Permethrin for clothes) when outside. Whichever product you choose, please read and follow the instructions on the packaging. Of note, DEET and other insect repellants should not be used on children < 2 months old. For older children use DEET concentrations less than 30%. Oil of lemon eucalyptus should not be used on children less than 3 years old.
  • Avoiding outdoor exposure during times when mosquitos like to bite which is from dusk until dawn.
  • Wearing long sleeved clothes and socks when possible. While outdoors with infants and young children, cover playpens and strollers with mosquito netting.
  • Looking for and draining areas of standing water at your workplace or residence (i.e. flower pots, open trashcans etc.) where mosquitoes like to breed.

Again, while this finding is concerning it is not surprising. The risk of any serious outcome is still very low – and with the commonsense interventions listed above this risk can be made even lower.

See below for additional resources regarding West Nile Virus from the CDC, Massachusetts DPH.

The CDC website for West Nile Virus:
The CDC website for insect bite prevention:
The Massachusetts DPH website for West Nile virus:
The Massachusetts DPH website for insect bite prevention:


Bryant “Bear” Benson MD, FAAP
Director of Medical Services
Deerfield Academy Health and Wellness Center