Staging a War Against West Nile and Eastern Equine Encephalitis

Jul 24, 2014

West Nile was first identified in Connecticut in 1999, and has persisted in the state ever since.

Mosquitoes trapped in East Haven are the first this year to test positive for West Nile Virus.

First, a few facts about mosquitoes. Only females feed on blood -- they need the protein to lay eggs -- and there are about 50 different species of the bug in Connecticut. "Most of the ones that feed on people we consider nuisance mosquitoes," said Philip Armstrong, medical entomologist at the Connecticut Agricultural Experiment Station. "They're more like pests. They're not involved in the transmission of any viral diseases."

Last year, Armstrong said there were four human cases of West Nile in the state. He said the majority of mosquitoes infected with West Nile belong to one species, Culex pipiens, the common house mosquito, which lays eggs in water and is commonly found in urban and suburban settings. 

West Nile was first identified in Connecticut in 1999, and has persisted in the state ever since. From 2000 to 2013, a total of 114 West Nile Virus-associated illnesses have been reported to the state Department of Public Health with the majority of those cases originating in Fairfield County

World War II era pamphlet aimed to discourage creation of stagnant water.
Credit Wikimedia Commons

The state has 91 locations to trap mosquitoes and test them for West Nile, but Armstrong said scientists are also screening for another disease, one that's very rare, but potentially way more serious: Eastern Equine Encephalitis.

"What we often refer to as EEE virus is really the most dangerous mosquito-borne disease in North America," Armstrong said. "About a third of those who develop the encephalitis die from the illness."

Usually there are fewer than ten cases of EEE per year in the entire country. Last year, the infection hit home, killing a Connecticut man. It was the first EEE death recorded in Connecticut, but Armstrong said New England has a history with the illness dating back to the 1930s, when an outbreak hit Massachusetts, killing 25.

A similar epidemic struck New Jersey in 1959, resulting in 32 infections, and more deaths. In 2012, The Boston Globe reported seven EEE infections in Massachusetts, resulting in three deaths

EEE tends to target horses and domestic birds, and can only be spread via mosquito vectors. That means an infected human with EEE isn't contagious.

Armstrong said there are easy ways to mitigate infection risk: Cover up your body, and if possible, avoid going outdoors around dawn and dusk.