Connecticut Adds New Test Site for EEE in Lyme, Old Lyme and East Lyme

A map of mosquitoes in Connecticut testing positive for Eastern Equine Encephalitis (Credit: The Connecticut Agricultural Experiment Station)


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For the first time ever, the state of Connecticut began testing freshwater habitat in Old Lyme for mosquitoes likely to carry Eastern Equine Encephalitis. For the last 20 years the state has had a testing site for mosquitoes in Old Lyme, but in saltwater habitat on Great Island more suitable for mosquitoes carrying West Nile Virus.

The new site for testing was established this week in the interior region of Old Lyme, Lyme and East Lyme, near to where positive results were found for the Eastern Equine Encephalitis virus on Wednesday. 

This new testing supplements regular testing by the Connecticut Agricultural Experiment Station (CAES) at Cedar Lake in Lyme. Until this week, Cedar Lake has been the only site in Lyme, Old Lyme, or East Lyme testing freshwater habitat.

Tests at the Cedar Lake location were negative on August 26 and September 10. The last positive test for EEE at Cedar Lake in Lyme was in 2009. 

Philip Armstrong, medical entomologist at CAES, said the new “supplemental site” borders Old Lyme, Lyme and East Lyme was added as of Sept. 23 because of the deaths of two people in the area during the last month. CAES has 91 trapping sites located throughout the state. 

“In light on recent human cases, we’ve wanted to increase our coverage in the area and so we added a number of new sites to get a better sense of risk in the area,” Armstrong said by phone Thursday.  “It’s mainly in habitats — these hardwood swamps habitats where we tend to see more risk for EEE virus. We wanted to get a better sense of what the risk was in more interior parts of the town and neighboring towns 

CAES has been testing saltwater mosquitoes at Great Island for 20 years, but “that was more of a coastal habitat, so we wanted to increase the coverage in the area,” Armstrong said of adding the new site.

Armstrong said CAES will continue trap at the new site “as frequently as we can” despite limited staff and funding.

“We’re doing what we can to get as much trapping out there and as much information as possible,” he said. “What it does say to me is that the risk is continuing and that we are continuing to detect positive mosquitoes in the area.” 

Adding the site was the result of collaboration among multiple state, health and municipal officials, he said. 

“That was a group decision to add the site, part of a consultation with the Department of Public Health and with our agency and with the town officials,” he said. “We’ve been in conversation with town officials and the local health district really every week.”

CAES will evaluate whether to make the new site a permanent trapping location and funding will be a strong factor in the decision, he said. 

“We’ll re-evaluate that at the end of the year to see whether we want to move our trap site in Old Lyme, to maybe move things around. We’ll look at that data at the end of the year, so we may adjust our trapping locations to get a better sense — absolutely, so that’s on the table,” he said.

“That really depends on funding levels, we’re kind of already at capacity as to how many traps we can handle and this is a state-wide surveillance program so we have to have coverage in other areas as well but unless our funding increases and we have additional personnel, it would be hard to add extra sites.” 

Armstrong said that the EEE virus is a regional problem and does not distinguish between town borders.

“We’ve been warning all along that the risk is throughout eastern Connecticut and you have to look at the data on a regional basis, so you can’t just look at a trap in any one town, and base your conclusions on one trap, you have to look at all the traps in the area and in neighboring towns,” he said. “What we’ve seen all along is there’s an increased risk of EEE throughout the southeastern portion of the state so you have to look at the data in aggregate, you can’t just look at one town in isolation.”

Stephen Mansfield, executive director of Ledge Light Health District, which serves as the health department for Old Lyme, Lyme and East Lyme, confirmed the new trapping site was established this week. 

“They installed three traps in Old Lyme and Lyme and also three additional traps in East Lyme,” Mansfield said by phone Thursday. “Those traps were put in in response to the two human cases. They’ve been trapping at strategic locations across the state at 90-something sites and there weren’t any in this particular area and so the Ag station decided to put some traps in there and see what they could actually find.”

Mansfield said that the public needs to know the EEE virus is endemic to southeastern Connecticut.

“Just because a particular municipality doesn’t test or maybe doesn’t even have traps doesn’t mean that the virus is absent,” Mansfiels said. “The traps are really sentinels. They’re stations set up across the state to give us a good picture of what the level of mosquito activity is and whether those mosquitoes are actually carrying any mosquito-borne illnesses, so it shouldn’t be focused on a particular neighborhood or even town, everyone in southeastern Connecticut should be employing the same preventive measures.”

Mansfield said Ledge Light recommended not going into swampy areas and avoiding activities from dusk to dawn until the risk of EEE has been removed.

“There are always going to be pockets that have higher mosquito activity but again the takeaway message is everyone in Southeastern Connecticut should employ those protective measures,” he said.