About Babesiosis disease

Move over, Lyme disease: Another tick-borne illness is on the increase in various parts of the country, and this one can kill.

Known as babesiosis, the disease is caused by a microscopic parasite that attacks blood cells, causing flu-like symptoms that can make it difficult to exactly diagnose. Like Lyme disease, which is caused by bacteria, babesia microti parasites are passed by deer ticks.

First documented in Massachusetts in 1969, the once-obscure babesiosis has surfaced as a significant public health hazard in parts of the Northeast and Upper Midwest over the last several years. And many cases may be avoidance detection, experts say.

I think it was underreported. “One of the reasons we are seeing more about it is because people are becoming more aware," said Dr. Peter Krause, a babesiosis researcher and senior research scientist at the Yale University School of Public Health. "The theory is that it's spreading from east to west, as if you were dropping a pebble in a pond and it spread outward geographically."

About 1,000 cases are reported once a year in affected locales, Krause said, but many people with babesiosis have no symptoms and never know they're harboring the parasite. For others, symptoms can take in high fever, severe headache, fatigue, chills, and muscle aches and pains. It is treated with antimicrobial drugs, such as antibiotics.

People with compromised protected systems - including the older and those with cancer, HIV or no spleens -- are especially at risk of potentially deadly complications such as organ failure. Between 10 percent and 20 percent of patients in those populations pass away as a result, Krause said.

The more prolific Lyme disease causes similar symptoms in early stage cases but is easier to diagnose by its gossip bull’s eye rash, said Dr. Barbara Herald, a medical epidemiologist at the CDC who specializes in parasitic conditions.

Deer are essential to the life cycle of ticks carrying the babesia microti parasite by serving as a blood meal, shelter and a place to mate, Krause said. Ticks also feed on birds, who serve as carriers for Lyme disease, which affects the entire continental United States. Fortunately for humans, birds don't carry babesia microti.

Krause noted that ticks need a moist climate to thrive, so dry states such as Arizona are not likely to see babesiosis cases caused by tick bites. But the disease can potentially increase to all states in an even sneakier way -- through the blood supply.

Although a blood screening test is in trials, Krause said, donors are presently only asked if they have had babesiosis, and those who harbored it but never showed symptoms can pass it through their donated blood. And because most blood recipients are already physically compromised, babesiosis has about a 30 percent humanity rate in that group, he said.

The authors of the study also advised clinicians to consider babesiosis in patients who have been exposed to ticks or received blood products and who show up for treatment with a fever and anemia resulting from the destruction of red blood cells.