Cape tick-borne disease cases on the rise, but underreporting still suspected

June 20--While newly released statistics show tick-borne diseases are on the rise in Barnstable County, state officials say the cases represent a fraction of actual diagnoses and they are looking for new ways to count Lyme disease.

More than 700 people on Cape Cod received positive lab tests or physician diagnoses of Lyme in 2016, but only 245 met Centers for Disease Control and Prevention surveillance guidelines for confirmed and probable cases, Massachusetts Department of Public Health Deputy Epidemiologist Catherine Brown wrote in an email last week.

Even the CDC estimates that "cases may be underreported by a factor of 10," Brown wrote.

That means the 30,000 cases reported nationally each year are more likely 300,000, according to a statement released last week by the office of U.S. Rep. William Keating, D-Mass., in which he announced a new Lyme prevention bill.

The Tick-Borne Disease Prevention Act would direct the CDC to update prevention and treatment procedures and provide training materials for health care providers.

Improved education about tick-borne infections should help improve diagnostic accuracy, Dr. Lisa Nigrovic, associate professor of pediatrics and emergency medicine at Harvard Medical School, said in Keating's statement.

"Because Lyme disease is underreported, the standard case definition method of counting cases does not accurately reflect the true burden of Lyme disease," Brown wrote.

In 2008, the national case definition for Lyme disease was changed to include probable cases.

Probable cases are physician-diagnosed cases of Lyme disease with laboratory evidence of infection, according to the CDC.

In confirmed cases, the patient also has the erythema migrans rash and either lives in a high incidence area or has a known exposure to a deer tick bite.

Confirmed cases also include late-stage manifestations with laboratory evidence of infection.

But advocates for patients with Lyme disease said not everybody with Lyme gets a rash.

And not all the information about Lyme patients makes it way to public health authorities, so surveillance numbers are artificially low, according to Brown.

For instance, in 2016, 740 patients in Barnstable County had either a positive lab result or physician report of Lyme. In 2015 there were 613 such patients, Brown wrote.

But the state received enough data on only about one-third of the cases to include them in surveillance figures, she wrote.

The most recent Lyme cases for Barnstable County, which the Department of Public Health supplied at the request of the Times, were 245 confirmed and probable Lyme disease cases in 2016 and 166 cases in 2015.

State public health officials are exploring alternatives to the standard case definition that would make "better assessments about the burden posed by Lyme disease in Massachusetts," Brown wrote.

The new method might include looking at insurance databases to look for patient visits coded to relate to Lyme disease, she wrote.

In 2015, the CDC reported that while only 30,000 people in the U.S. met its surveillance standards for Lyme disease, other studies suggested the number was more like 300,000.

One study looked at laboratory results that yielded 288,000 positive Lyme tests in 2008. Another study found annual medical claims for treatment for Lyme disease averaged around 329,000.

Lisa Freeman, of Brewster, a nurse who helps run the Cape Lyme Advocacy Support Program, said Lyme patients won't get the help they need without mandatory education on Lyme disease for medical practitioners charged with making diagnoses.

"That's the next step," she said.

Henry Lind, co-chairman of the Barnstable County Tick-Borne Diseases Task Force, wrote in an email that the task force is in the process of planning a statewide symposium to pick up where a 2013 legislative task force and report on Lyme disease was dropped.

The recommendations were "for the most part implemented piecemeal if at all," Lind wrote.

-- Follow Cynthia McCormick on Twitter: @Cmccormickcct

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