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NH DHHS Identifies First Mosquito Batches in 2018 to Test Positive for Eastern Equine Encephalitis
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Bureau of Infectious Disease Control
Publish Date:
September 24, 2018

Concord, NH – The New Hampshire Department of Health and Human Services (DHHS) has identified the first batches of mosquitoes to test positive for Eastern Equine Encephalitis (EEE) this season. The batches were found recently in the towns of Newton and Sandown and DHHS is working in partnership with the Newton and Sandown Health Officers to notify residents.

"These detections of EEE in mosquitos serve as a reminder for the need to protect oneself against mosquito bites to prevent EEE and other mosquito-borne diseases," said NH State Epidemiologist, Dr. Benjamin Chan. "Even with the cooler weather, there are still mosquitos that are out and biting. The most effective ways to prevent mosquito bites are to use an effective mosquito repellant that contains 30% DEET, avoid being outdoors at dawn and dusk, and remove standing water from around the home where mosquitos reproduce."

EEE was first identified in New Hampshire in August of 2004. This season, the DHHS Public Health Lab has tested 4,135 mosquito batches, 11 animals, and 18 people for West Nile Virus (WNV) and EEE. In addition to the two positive EEE mosquito batches in Newton and Sandown, 29 mosquito batches in NH have tested positive for WNV.

Symptoms of EEE virus often appear 4 to 10 days after being bitten by a mosquito carrying the EEE virus. People who get sick from EEE can develop a flu-like illness, including fever, headache, weakness, and muscle and joint pains. A more serious central nervous system infection can develop such as meningitis and encephalitis (inflammation of the brain). EEE typically causes a more serious disease than WNV and carries a high mortality rate for those who contract the serious encephalitic form of the illness. There is no specific treatment for the disease.

Prevention guidelines for EEE and other mosquito-borne diseases can be found below. Anyone with questions about mosquito-borne diseases, including EEE, can call the New Hampshire Bureau of Infectious Disease Control at 603-271-4496.

Infectious Disease Fact Sheets, including one on Easter Equine Encephalitis Adobe Acrobat Reader Symbol are available. For more information, please visit the Centers for Disease Control and Prevention website at

Prevention Guidelines for West Nile Virus and Eastern Equine Encephalitis

1. Eliminate standing water and other mosquito breeding locations.
In warm weather, mosquitoes can breed in any puddle that lasts more than 4 days!

  • Remove old tires from your property.
  • Dispose of tin cans, plastic containers, ceramic pots, or other containers. Don’t overlook containers that have become overgrown by aquatic vegetation.
  • Drill holes in the bottom of recycling containers that are left outside.
  • Make sure roof gutters are clean and draining properly.
  • Clean and chlorinate swimming pools and hot tubs. If not in use, keep empty and covered and keep covers free of standing water.
  • Aerate garden ponds or stock them with fish.
  • Turn over wheelbarrows and change water in birdbaths at least twice weekly.
  • Turn over plastic wading pools when not in use.
  • Remind or help neighbors to eliminate breeding sites on their properties.

2. Be aware of where mosquitoes live and breed and keep them from entering your home.

  • Mosquitoes lay their eggs in standing water. Weeds, tall grass, and bushes provide an outdoor home for adult mosquitoes, including several species commonly associated with West Nile virus and Eastern Equine Encephalitis.
  • Mosquitoes can enter homes through unscreened windows or doors, or broken screens. 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.

3. Protect yourself from mosquito bites.

  • If outside during evening, nighttime, and dawn hours when mosquitoes are most active and likely to bite, children and adults should wear protective clothing such as long pants, long-sleeved shirts, and socks.
  • Consider the use of an effective insect repellent, such as one containing DEET. A repellent containing 30% or less DEET (N,N-diethyl-methyl-meta-toluamide) for children and adults. Use DEET according to the manufacturer's directions. Children should not apply DEET to themselves. Repellents that contain Picaridin, para-menthane-diol or oil of lemon eucalyptus have also been determined to be effective.
  • Vitamin B, ultrasonic devices, incense, and bug zappers have not been shown to be effective in preventing mosquito bites.

For more information on West Nile Virus or Eastern Equine Encephalitis, visit the Eastern Equine Encephalitis and West Nile Virus web page.

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New Hampshire Department of Health and Human Services
129 Pleasant Street | Concord, NH | 03301-3852

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