CDC estimates 300,000 new Lyme disease cases yearly


HARTFORD, Conn. — Officials from the federal Centers for Disease Control and Prevention said Monday that about 300,000 people in the United States are diagnosed with Lyme disease each year — about 10 times as many as are officially reported.

The estimate was first announced Sunday at the 2013 International Conference on Lyme Borreliosis and Other Tick-Borne Diseases in Boston.

Getting a better handle on the number of cases could help health officials better prioritize policies for preventing and treating Lyme disease, and give the public a better sense of the risk of getting it, said Dr. Paul Mead, chief of epidemiology and surveillance for the CDC’s Lyme disease program.

CDC officials said they have long believed that the number of reported cases is only a fraction of the actual number. Studies in the 1990s suggested that the actual number of cases was three to 12 times the reported number, but this is the first time that the CDC has attempted to get an official tally.

“It’s important to recognize that unreported cases doesn’t mean that they aren’t diagnosed or treated,” Mead said. “What happens is that busy health care providers treat Lyme disease but don’t end up reporting it to health authorities. This isn’t special to Lyme disease at all.”

Mead stressed that the officially reported data are still useful in determining where the disease is most prevalent and who is most at risk. Those numbers have long told health officials that the disease is especially concentrated in the Northeast and upper Midwest.

Ninety-six percent of Lyme disease cases come from 13 states. Lyme disease — the most common tick-borne disease — was first identified by a researcher at Yale University in the mid-1970s among residents of Lyme and Old Lyme in Connecticut.

Typical cases often present with a “bulls-eye” rash close to the tick’s bite, followed by flu-like symptoms, such as muscle and joint aches, chills, headache, fever and fatigue.

To get a better estimate of the number of people with Lyme disease, Mead said, the CDC used the results of three studies. One analyzed the insurance claims of about 22 million people over six years, another is based on surveys of clinical laboratories and a third is based on a survey of the general public.

Although not all Lyme disease experts are convinced that it will have much effect, Mead said that having a more accurate number has certain benefits.

“It’s helpful for policymakers and scientists, research and development and the general public to have the idea of the magnitude of the problem,” he said. “It’s simply a way to help people set priorities, to know how big the problem is compared to other problems.”

One result is that it could help steer funding, he said. But he said his main hope is that it will nudge people to take more precautions to prevent getting Lyme disease. That includes checking for ticks, wearing repellent and landscaping your yard to minimize the tick population.

Dr. Philip Baker, president of the American Lyme Disease Foundation in Lyme, said he doesn’t think that the estimate is especially significant.

“I wouldn’t make a whole lot out of it,” Baker said, “because we already know what you really need to know, which is that there’s a lot of Lyme disease.”

Baker said he hoped that the CDC hadn’t spent too much money getting the estimate, adding that he would prefer that funds go to education about the disease.