Prime tick season is approaching, and those creepy little arachnids are carrying all sorts of diseases, including a rare one that’s becoming more prominent: Annual reported cases of babesiosis—a tick-borne disease that can trigger flu-like symptoms, and lead to life-threatening complications in vulnerable people—doubled in the United States between 2011 and 2019, and the true number of infections is probably much higher, according to a recent report from the Centers for Disease Control and Prevention (CDC).
Babesiosis is now endemic—meaning it occurs regularly but is contained to specific regions—in at least 10 states in the Northeast and Midwest, but the disease has been detected in many others. Babesiosis is not nearly as common as Lyme disease, the most common tick-borne disease in the country; 16,456 cases of babesiosis were reported to the CDC between 2011 and 2019, while roughly 30,000 cases of Lyme are reported to the CDC each year. Both diseases are likely underdiagnosed and underreported: Lyme is believed to affect up to 476,000 people in the U.S. each year, and the true burden of babesiosis remains unclear, as it’s not required to be reported in all states.
While it’s still somewhat rare, it’s not exactly great news that babesiosis is gaining traction. Lyme disease is caused by Borrelia burgdorferi bacteria, which are “loosely related to syphilis,” Thomas Russo, MD, an infectious disease expert at the University of Buffalo Jacobs School of Medicine and Biomedical Sciences, tells SELF. The pathogen that causes babesiosis, Babesia, “is a parasite that invades red blood cells. It’s a completely different beast.”
Curious about what that means? Here’s what you should know about babesiosis, including where it’s stirring up the most trouble so far, the symptoms it can set off, and how to protect yourself from tick bites as you enjoy the warmer weather.
Where is babesiosis spreading?
Babesiosis is mainly transmitted through the bite of an infected blacklegged tick (aka a deer tick), which is also known to carry Lyme-causing bacteria, among other harmful pathogens. Most human Babesia infections are caused by the microscopic parasite Babesia microti.
Because these parasites infect red blood cells, babesiosis can also spread via blood transfusions, during organ transplants from infected donors, or from an infected pregnant person to a fetus. “The expansion of babesiosis risk could have implications for the blood supply,” the CDC report notes. “[People] who acquire babesiosis through contaminated blood have been shown to have significantly worse health outcomes and a higher risk for death than do those who acquire the disease from a tick bite.” (Note: the Food and Drug Administration recommends blood donation screening for babesiosis in 14 states and D.C.)
Babesiosis is considered endemic in the following states: Connecticut; Massachusetts; Minnesota; New Jersey; New York; Rhode Island; Wisconsin; Maine; New Hampshire; and Vermont.
Vermont, Maine, and New Hampshire are recent additions to this list due to “significantly increasing incidences” of the disease in these states, the CDC notes. Connecticut, Massachusetts, New Jersey, New York, and Rhode Island also saw significant increases.
