State concludes mosquito testing, EEE hit record highs

Though West Nile Virus is typically the dominant mosquitoborne virus circulating in Connecticut, 2019 was a blockbuster year for EEE, also a mosquitoborne disease.

There were four human cases of the illness in Connecticut and three deaths — significant, because there previously hadn’t been a human case of EEE since 2013.

It was a actually deadly year for EEE throughout the entire Northeast, with a total of 23 deaths in Connecticut, Massachusetts, Rhode Island and New Jersey.

“This is the biggest outbreak since 1959 when New Jersey experienced 33 cases,” said Dr. Theodore Andreadis, director of the Connecticut Agricultural Experiment Station, which conducts the state’s mosquito trapping and testing program. “I’ve never seen such activity over such a wide geographical area.”

The state has finished its mosquito trapping and testing for the season, ending the largest outbreak of Eastern Equine Encephalitis the northeast has seen in 60 years.

As of Nov. 7, no new positive cases have been identified since the last in midSeptember, and the trapping season has ended.

He said often an outbreak in southeastern Massachusetts may not be seen here or one in Rhode Island may not be evident in Massachusetts.

“This year it was widespread throughout the Northeast,” he said.

There was so much activity that Andreadis said he is seeking an additional $150,000 in state funding to place mosquito traps in 15 new locations in southeastern Connecticut and Tolland County where the virus was found.

“If we get that money, we can adequately cover the state and get no surprises,” Andreadis said.

He said the mosquitoes that carry the EEE virus are very difficult to contain and control. He said their larvae are usually found in subterranean crypts deep in the woods “and that requires aircraft” to spray pesticides over a large scale area.

“It’s hard to predict how much, but we’ll see activity next year,” he said.

A favorable environment for mosquitoes would be a mild winter with a lot of rainfall before summer.

Yet Andreadis said he is optimistic that the same amount of activity as this year “is unlikely because it was so unique.”

Overall, the state trapped and tested 239,660 mosquitoes since the program started in June. Of those, 122 tested positive for EEE, 82 tested positive for West Nile Virus and 20 tested positive for Jamestown Canyon virus, an emerging infectious disease that was first detected in Colorado in 1961.

This mosquito season stands in contrast to 2018, which was the worst the state had seen for West Nile Virus, with a total of 393 positive mosquito samples, 23 human cases of West Nile, and one death — the first since 2006. By comparison, this year there appeared to be only one human case of West Nile, in Danbury.

Another concern is that mosquitoes carrying EEE have also been found in towns where the virus isn’t typically detected — including those in Fairfield County, where the virus hadn’t been detected for roughly a decade.

Throughout the season, experts put some blame for the active EEE season on climate change, particularly an increase in warm temperatures.