State’s First EEE of Summer Found in Londonderry

The state Department of Health and Human Services (DHHS) announced Friday, Aug. 15, that New Hampshire’s first finding of Eastern Equine Encephalitis (EEE) this summer came from Londonderry.

Dr. Abigail Mathewson, acting state Public Health Veterinarian with DHHS and the department’s Surveillance Epidemiology Program Manager in the Bureau of Infectious Disease Control, said mosquitoes are collected at certain points determined by the contractor, in this case Dragon Mosquito Control, and are then tested for EEE or West Nile Virus.

“They will identify the mosquitoes by species and separate them and then divide them into groups,” she said. “One of the groups tested positive, so we can’t necessarily say how many mosquitoes within that group were positive, but there was at least one.”

Dr. Jose Montero, the state’s Public Health director, said that in 2013, New Hampshire had 27 positive tests for EEE, including 24 mosquito batches and three animals.

Montero noted, “EEE and West Nile Virus are transmitted by the bite of infected mosquitoes. This finding does not change the current low arboviral risk level for Londonderry. It is important that people continue to take precautions against mosquito bites, including wearing an effective repellent, long pants and sleeves; ensuring screens are in good repair; and removing standing water from property to prevent mosquitoes from breeding.” Arboviral refers to viruses transmitted to humans from mosquitoes or ticks.

“This is approximately the same time we identified the first positive for Eastern Equine Encephalitis as last year,” Montero added. “Since we know that the agents that cause these diseases are here in New England, everyone should make it part of their routine to take precautions every time they go outside.”

“Residents of New Hampshire should have been following all of our recommendations for use of insect repellants, removing standing water, maintaining bird baths and troughs, maintaining screens and things like that,” Mathewson said.

With the latest evidence of EEE, “people really need to be mindful,” she added. “Bird baths are great to have because it’s nice to have birds, but they should be cleaned at least twice a week. Scrub them out, change the water and make sure you’re not leaving standing water where mosquitoes can breed.”

On Friday, Town Manager Kevin Smith issued a similar statement announcing the findings of EEE in a Londonderry batch of mosquitoes collected for testing.

“The mosquito species, Culiseta melanura, is the primary vector of EEE and mainly bites birds but will occasionally, although rarely, bite mammals including humans,” the statement said.

“I recommend that horse owners have their horses vaccinated,” Mathewson said. “Both EEE and West Nile Virus are maintained in birds in our state, so there’s a period of time where there are mosquitoes that preferentially feed on birds and take the virus from bird to bird, and there is another type of mosquito that is called a bird vector and they also bite birds and mammals, so that’s where it spreads.”

If illness from EEE does occur, it happens within four to 10 days after being bitten by an infected mosquito. If someone is experiencing flu-like symptoms, including fever and headache, they should contact their local medical provider.

Montero noted that EEE is a more serious disease than West Nile Virus and carries a high mortality rate for those who contract the serious encephalitis form of the illness. Symptoms may include high fever, severe headache, stiff neck, and sore throat. He said there is no treatment for the disease, which can lead to seizures and coma.

The risk of contracting EEE or West Nile Virus does not end until after two hard frosts, which is likely to be after Halloween in southern New Hampshire. Until then, residents are advised to take personal precautions to prevent being bitten by mosquitoes.

No positive findings for West Nile Virus in New Hampshire have been found as yet this year.

For more information about EEE or West Nile Virus, contact Dragon Mosquito Control at 734-4144 or email, or the DHHS website at and the Centers for Disease Control and Prevention website at

For questions, contact the DHHS Bureau of Infectious Disease Control at 271-4496.

Prevention guidelines for EEE:

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

• Remove old tires from your property.

• Dispose of tin cans, plastic containers, ceramic pots, or other containers.

• 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 them 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.

• Weeds, tall grass, and bushes provide an outdoor home for adult mosquitoes, including several species commonly associated with West Nile Virus and EEE. Mosquitoes can enter homes through unscreened windows or doors, or broken screens. Make sure doors and windows have tight-fitting screens. Repair or replace all screens with tears or holes.

• Resting mosquitoes can often be flushed from indoor resting sites by using sweeping motions under beds or behind bedside tables and once in flight, can be exterminated prior to sleeping at night.

• If outside during evening, nighttime, and dawn hours when mosquitoes are most active and likely to bite, children and adults should wear long pants, long-sleeved shirts, and socks.

• Consider the use of an effective insect repellent, such as one containing 30 percent or less of DEET (N,N-diethyl-methyl- meta-toluamide) for children and adults. Children should not apply DEET to themselves. Repellents that contain Picaridin 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.

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