Report: Pa. Lyme disease numbers are up

Just in time for peak tick season, the Pennsylvania Department of Health this week announced that Lyme disease cases went up by a whopping 25 percent in a single year. Given the state often has more cases of the tick-borne infection than any other, this might worry anyone who spends time in the woods.

But experts say a lot goes into reports such as this one, some of it concerning, some perplexing - and some reassuring.

"We know Lyme is out there," said Atmaram Nambiar, director of the Division of Infectious Disease Epidemiology at the Department of Health. "But, like any other disease, it depends on how you interpret the data."

Overall, reported cases throughout Pennsylvania rose from 5,904 in 2013 to 7,487 in 2014.

But Philadelphia dipped by 40 cases. And heavily wooded Chester County - known as a hot spot for ticks - fell by 293.

At the other end of the state, Allegheny County shot up by nearly 800 cases. That, experts agree, is because of stepped-up surveillance, not because the Pittsburgh area is suddenly surging with Lyme disease.

Lyme disease symptoms include fatigue, fever, and, the characteristic bull's-eye rash. Since 1991, cases have had to be reported to health departments, using consistent criteria set by the U.S. Centers for Disease Control and Prevention.

Consistent, but not simple.

"The case definition for Lyme is really complicated," said Kirsten Waller, head of surveillance in the Division of Infectious Disease Epidemiology.

It can be a difficult disease to diagnose, she said. "The symptoms of Lyme disease, with the exception of [the bull's-eye rash], are pretty nonspecific and can be caused by a number of conditions besides infection" by the bacterium that causes Lyme.

In addition to misdiagnosis, there also are issues with underreporting and the fact that cases are logged by county of residence, not by where the patient was exposed.

Lyme gets a lot of public attention, especially with some patients reporting long-term suffering.

"Are people complying more [with reporting requirements]? Are people more aware of it?" Waller asked. "Are the local jurisdictions expending more resources? Sometimes we just can't tease out what is real or what is due to better reporting."

Stephen Gluckman, an infectious diseases expert at the Hospital of the University of Pennsylvania, said he thinks there likely is an increase in Lyme cases, but whether it's 25 percent statewide is impossible to say.

"I think it's probably a combination of factors," he said of the reported increase's size. "The question is always, 'Is this actually real?' It's often hard to sort out. It's almost surely a matter of both" a real increase and other factors.

Might there be another way to report data without inciting unnecessary worry? The Health Department has tried, Waller said, but people tend to like "simple messages."

Although the numbers are not straightforward, the reports still matter, she said: "It's important to document that Lyme is throughout the state. It's important that [the public] takes the prevention messages seriously."

Whatever the numbers, Lyme disease is serious, and taking precautions is essential, experts agree.

Especially when in the woods, wear long pants and socks, check the skin thoroughly for ticks afterward - and don't shy away from chemicals.

"The most important thing, really, is a good insect repellent," Gluckman said. "The only effective insect repellent has the active ingredient DEET."

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