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The Riskiest Time of Year for Eastern Equine Encephalitis
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Issued by Division of Public Health Services
Publish Date:
October 2, 2019

Concord, NH – The New Hampshire Department of Health and Human Services’ (DHHS) Division of Public Health Services (DPHS) reminds people that the risk of diseases from mosquitoes is still present until we experience a statewide hard frost when temperatures drop below freezing for several hours.

“Fall is the riskiest time of year for contracting diseases from mosquitoes. Although mosquito populations have decreased, the ones that are still around are more likely to be infected with diseases like Eastern Equine Encephalitis. It is critical to keep using personal protective measures like insect repellent this time of year,” said Lisa Morris, DPHS Director. “Many people are outdoors enjoying fairs, hunting, hiking, and biking. We want everyone to enjoy these activities while taking the appropriate steps to prevent mosquito bites that may cause serious and potentially fatal illnesses.”

Insect repellants should continue to be worn for outdoor activities by everyone, including children at daycare centers. New Hampshire people and animals are at risk for three mosquito-borne diseases: Eastern Equine Encephalitis (EEE) Adobe Acrobat Reader Symbol , West Nile Virus (WNV) Adobe Acrobat Reader Symbol, and Jamestown Canyon Virus (JCV) Adobe Acrobat Reader Symbol. Since 2004, there have been 15 human infections with EEE identified in NH. WNV was first identified in NH in 2000 and since then there have been seven cases. Since 2013, a total of seven JCV cases have been reported.

Only 37 New Hampshire towns and cities collect mosquitoes for disease testing, leaving the vast majority without scheduled trapping and testing. You may have EEE, WNV, or JCV circulating in your area and not be aware because testing is not being performed in your town. Reports of all EEE, WNV, and JCV identifications for this season as well as a map of the towns providing mosquito trapping Adobe Acrobat Reader Symbol can be found on our website.

Do not forget that this time of year ticks are also active and biting. Tick bite prevention is also important until there is snow covering the ground. Guidelines for mosquito and tick bite prevention are listed below. More information is available on the DHHS website, and on the Centers for Disease Control and Prevention website at Anyone with questions about arboviruses can call the New Hampshire Bureau of Infectious Disease Control at 603-271-4496.

Prevention Guidelines for Mosquito and Tick Diseases

  • Eliminate habitat and breeding locations.
    • Mosquitoes
      • Mosquitoes lay their eggs in standing water. Remove outdoor items that hold water (old tires, cans, plastic containers, ceramic pots).
      • Drill holes in the bottom of outdoor recycling containers, clean roof gutters and ensure proper drainage.
      • If not in use, empty and/or cover swimming pools, wading pools and hot tubs.
      • Turn over wheelbarrows and change water in birdbaths at least twice weekly.
      • Minimizing areas where hosts for the ticks, such as rodents and deer, can congregate to eat, sleep or feed.
  • Be aware of where mosquitoes and ticks live.
    • Weeds, tall grass, and bushes provide an outdoor home for mosquitoes and ticks, alike.
    • Make sure that doors and windows have tight-fitting screens. Repair or replace all screens in your home that have tears or holes.
    • Resting mosquitoes can often be flushed from indoor resting sites by using sweeping motions under beds, behind bedside tables etc. and once in flight, exterminated prior to sleeping at night.
    • Avoid tick-infested areas. If in tick-infested areas, walk in the center of trails to avoid contact with overgrown grass, brush, and leaf litter at trail edges.
  • Protect yourself from bites.
    • When outside, wear protective clothing such as socks, long-sleeved shirts, and long pants (preferably tucked in socks). Light-colored clothing helps you spot ticks.
    • Wear insect repellents, such as one containing 30% or less DEET (N,N-diethyl-methyl-meta-toluamide), Picaridin, para-menthane-diol, IR3535, or 2-undecanone or oil of lemon eucalyptus.
      • Treat clothing with permethrin, ideal for hunters as it is odorless when dry.
    • Vitamin B, ultrasonic devices, incense, and bug zappers have not been shown to be effective in preventing mosquito bites.
    • Shower as soon as possible after spending time outdoors.
    • Check for ticks daily, on you and your pets. Ticks can hide under the armpits, behind the knees, in the hair, and in the groin.
    • Wash and dry clothing after being outdoors. Tumble clothes in a dryer on high heat for 10 minutes to kill ticks on dry clothing. If the clothes are damp, additional time may be needed.
    • Early removal of ticks can reduce the risk of infection. Inspect all body surfaces carefully, and remove attached ticks with tweezers. Monitor your health closely after a tick bite and be alert for symptoms of illness. Contact your physician to discuss testing and treatment.
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New Hampshire Department of Health and Human Services
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