As tick season arrives, add babesiosis to Lyme disease concerns

Close up photo of adult female deer tick crawling on piece of straw; Shutterstock ID 342282746; PO: OPED
Shutterstock / Steven Ellingson
An adult female deer tick crawling on piece of straw.

Dr. Fiona Breslin recently treated a patient at Addison Gilbert Hospital in Gloucester who had been bitten by a deer tick. But the diagnosis wasn’t Lyme disease.

Tests showed the patient had babesiosis, which in severe cases can result in serious anemia or spleen rupture and can be life-threatening. Most of the time, it goes undetected in young, healthy people, who often experience only flu-like symptoms or no symptoms at all.

“The spleen rupture is extremely rare,” said Breslin, who works in the emergency department. “I have only seen two cases of that in the past 10 years. Babesiosis itself is relatively rare, less common than Lyme disease, but it has been increasing.”


Dr. Maria Diuk-Wasser of the Department of Ecology, Evolution, and Environmental Biology at Columbia University, has been studying babesiosis in her lab and recently published a paper on how tick-borne diseases spread.

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“It is very similar to malaria,” she said of babesiosis. “It is basically caused by a protozoa, a microorganism, that infects through ticks, specifically the deer tick. It’s relatively new; in a matter of five years, it has increased in abundance. Ten years ago, it was not there at all, maybe.

“There is evidence that it is increasing in the New England area, moving north, following Lyme disease.”

Breslin said often people are treated for Lyme disease and if they don’t recover, they are then tested for babesiosis.

Babesiosis was first noted as a national threat in 2011, with over 1,000 cases reported to the Centers for Disease Control and Prevention. According to the Massachusetts Department of Public Health, 191 of those cases occurred in Massachusetts.


The number of confirmed cases of babesiosis increased to 445 in 2015. The majority occurred on Cape Cod, and 58 percent of all patients in the state were 60 years or older, Department of Public Health.

In 2014 — the most recent year for which data are available — there were 3,646 confirmed cases of Lyme disease in the state.

Both Lyme disease and babesiosis are treated with antibiotics. Breslin said they are about equal in terms of dangerousness, but that babesiosis is sneakier.

“It’s hard to diagnose,” she said. “It does not have clear-cut symptoms like Lyme, and people are still becoming aware of it. If you’re young and healthy, you will generally do fine, and you will clear yourself of it.”

Christina Bagni can be reached at