2018 Lyme rate likely to remain steady
Maine reported drop after drought, Connecticut had tick-friendly winter
Last year will likely turn out to be an average year for Lyme disease infections in Connecticut, unlike in Maine, which experienced a dramatic decrease in 2018, possibly caused by a drought in that state.
“We have to be very careful to use precipitation as a proxy for the number of Lyme disease cases in humans,” said Goudarz Molaei, director of the tick-testing program at the Connecticut Agricultural Experiment Station in New Haven and a professor at the Yale School of Public Health.
“I think that based on the trend that we have had … we are going to have (an) average number of Lyme disease cases, not substantially lower,” he said. Final totals won’t be in until April, however, Molaei said.
According to the Portland Press Herald, Maine’s reported Lyme disease cases dropped by 29 percent in 2018, although final figures were not yet in. Unlike Connecticut, the original epicenter of Lyme disease, where infections have been gradually dropping through the years, the number of cases has been rising in Maine, from 175 in 2003 to 1,852 in 2017, a record, based on data from the Maine Center for Disease Control and Prevention.
In fact, 2018 was only the fourth year since 2003 in which Lyme disease cases in Maine didn’t set a record. There were 1,310 cases last year, lower even than 2016’s 1,464, the Press Herald reported.
Connecticut had a hot summer, with an average temperature of 71.3 degrees from June to August, more than 3 degrees above the norm, and an average fall, according to the Northeast Regional Climate Center, based at Cornell University. Bridgeport’s temperatures rose above 90 a dozen times by Aug. 31.
But it was also a wet summer and fall, with an average rainfall of 14.81 inches, 117 percent of normal, from June to August, and 21 inches, 159 percent higher than average, from September to November, according to the center.
Molaei said hot, dry conditions may lead to fewer deer ticks and, thus, fewer cases of Lyme disease, which the tick passes on from deer and white-footed mice to humans. “It decreases tick activity because their survivability … is affected by the drought,” he said.
“We have not experienced such drought in recent years,” he said. “Last year, 2018 particularly, we had a hot summer but higher precipitation rate,” he said.
But rainfall isn’t always a good predictor of tick activity, he said. In 2013, “the precipitation was not that high (but) we had the highest number of Lyme disease cases, nearly 3,000 cases.”
According to the state Department of Public Health, Connecticut’s record for Lyme disease infection, first discovered in 1975 in the town of Lyme, was 4,156 cases in 2009, shortly after the state expanded its data-collection system. Since then the numbers have declined to a recent low of 1,752 in 2016. In 2017, there were 2,022 cases.