Health update: mosquito-borne illnesses and schools

Maine Department of Education in collaboration with Maine Center for Disease Control and Prevention (Maine CDC) is sharing this important guidance with schools regarding mosquito-borne illnesses. Maine CDC developed the information and guidance in this letter. Two mosquito-borne illnesses are considered a local risk in Maine: Eastern Equine Encephalitis (EEE) and West Nile virus (WNV).  Both are potentially serious viral infections transmitted to people from the bite of an infected mosquito.  The disease is especially severe in children (as well as adults over 50).  There is no vaccine or effective treatment for humans.  Therefore, prevention strategies are critical.

Maine saw the first human case of WNV in 2012 and the first human case of EEE in 2014. Maine did not identify any positive EEE or WNV mosquito pools, human cases, or animal cases in 2016 and to date in 2017. Massachusetts, New Hampshire, and Vermont identified mosquito pools positive for WNV in 2017 and Massachusetts identified a mosquito pool positive for EEE.

Maine also identified other mosquito-borne viruses including two cases of locally-acquired Jamestown Canyon virus and one case of travel-associated Zika virus to date in 2017. New Hampshire also identified one case of locally-acquired Jamestown Canyon virus.

The risk for contracting mosquito-borne diseases is highest from dusk to dawn and when temperatures are above 50 degrees (and especially above 60 degrees), since these are the conditions when mosquitoes are most actively biting.

Schools play an important role in preventing mosquito-borne illnesses.  Maine CDC and its consulting experts recommend:

  • Cover up outdoors. Children and others on outdoor field trips and participating in other outdoor activities for a significant amount of time when the temperature is above 50 degrees should be encouraged to cover up with long sleeve shirts, pants, and socks; and/or
  • Use repellent.   Use an EPA approved repellent containing DEET, picaridin, IR3535, or oil of lemon eucalyptus on exposed skin and/or clothing.  The repellent/insecticide permethrin can be used on clothing and can be effective through several washes.  Always follow the package directions.  For details on recommended repellents see:

    • School employees and volunteers must have authorization from parents or guardians before applying repellants to minor children (CMR 01-026, Chapter 10, Section 2.I.4.iii):

    • Schools that schedule practices or games at dusk or evening with temperatures above 50 degrees should encourage the use of repellant for all participants including coaches and observers.

Implement Integrated Pest Management strategies. Since we anticipate the risk from mosquito-borne illnesses to continue, schools should consult with their IPM Coordinator to review their IPM policy. Information on Maine’s School IPM Program can be found at

Please monitor Maine CDC’s arboviral website for the most up to date information on positives detected in the state. If mosquito-borne disease activity increases in your area, the following strategies should be implemented:

  1. Use EPA approved repellents. These should be available to both students and staff who are outdoors, particularly during dusk and dawn hours. If you have an outdoor event, repellent should be available to spectators as well to limit the risk of mosquito-borne diseases.
  2. Consult with your school IPM coordinator and implement a plan to reduce the number of mosquitoes and mosquito breeding sites on school grounds.
  3. Limit and/or reschedule evening outdoor activities. Unless the dusk temperature is forecast to be less than 50 degrees, limit or reschedule outdoor evening activities such as school athletic events so people are able to go indoors by one hour before sunset.

All these recommendations are especially true in those areas with previously-identified mosquito-borne illnesses. However, the lack of identified virus in an area of the state does not mean there is no risk.

Maine CDC has one-page fact sheets for EEE, WNV, and repellents which we encourage you to send home with students, share by email, and/or post on your school website(s), as you deem appropriate. You can access the facts sheet here:

Resources to learn more about mosquito-borne illness and mosquito control:

Maine Department of Education and Maine CDC continue to work very closely together and are greatly appreciative of your assistance in keeping Maine’s children and school communities healthy.

For further questions, contact Maine DOE School Nurse Consultant, Emily Poland at