State’s 2018 Lyme rate likely to remain steady

Maine reported drop after drought, Connecticut had tick-friendly winter

Last year will likely turn out to have been 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.

Molaei said the cause of the fluctuation in reported cases is not easy to determine and may be attributed to “a number of factors, including reporting irregularity.”

One reason may be that “because it is an endemic region, people in our state have developed awareness and they are avoiding tick bites,” Molaei said. Others who have developed Lyme disease multiple times may have “stopped paying attention to the illness” and take unused antibiotics or get them from their doctor without reporting their illness as Lyme.

However, the number of ticks isn’t decreasing.

“The average submission to our lab has been 3,000” by residents, health departments and doctors’ offices, although the number rose to 4,458 in 2017. According to the experiment station, the percentage of deer, or black-legged, ticks that tested positive for Lyme disease has ranged from 27 to 32 percent between 2013 and 2017.

In 2018, “even though we had slightly less tick submission to our laboratory,” back to 3,000, “nonetheless, the infection rate was at 38 percent,” Molaei said. “This increase in infection rate for sure will have some influence or some impact on the number of Lyme disease cases that will be reported in 2018.”

Jocelyn Mullins, the state public health veterinarian, said “survey data is affected by many different things. There’s actual disease changes and tick changes and how data is reported to us.

“I would predict that we’re not going to have a big change from last year, but it’s really too early to say,” since final numbers are not in until April, she said.

Molaei said a reason for a potential increase in Lyme disease in Connecticut “is that the weather pattern has changed. We are seeing shorter winters and warmer winters that allows ticks to survive better.”

If ticks become active earlier, that will mean a larger generation later in the year.

“We are not having brutally or substantially cold winters that reduce the tick population,” he said. Warmer weather also creates favorable conditions for deer and mice hosts, he said.

There are two peaks of tick activity each year: April-May and October-November, Molaei said. There is also a peak in June, caused by nymphs, the stage between larva and adult. “Quite often they are overlooked because of their size and people cannot see them as easily as adult ticks,” he said.

Lyme disease is caused by the bacterium Borrelia burgdorferi. While Lyme-infected tick bites often can be detected by a bull’s-eye rash, that is not always the case. The disease brings flu-like symptoms, such as muscle aches, fatigue and fever, but can include joint pain and swelling, meningitis and facial palsy, according to the state health department. It is usually cured with antibiotics.

Between 10 and 20 percent of patients report post-treatment Lyme disease syndrome, with ongoing symptoms of fatigue and joint or muscle aches, according to the department’s website. While its cause is unknown, many experts believe the syndrome is the result of damage to the sufferer’s immune system, according to the health department.

The Centers for Disease Control and Prevention records about 30,000 cases of Lyme disease nationally each year, most heavily in the Northeast, but that may be only one-tenth the number of actual cases, according to the CDC website.

“The take-home message is that Lyme disease and other tick-borne diseases are a significant public health problem in the United States and … particularly in New England and in our state,” Molaei said.

James Gathany / Associated Press A deer tick, also known as a black-legged tick, which spreads Lyme disease from deer or white-legged mice to people.