Cases of Babesiosis—a potentially fatal condition caused by microscopic parasites carried by blacklegged ticks—have sky-rocketed. Cases rose a stunning 1,602% in Vermont, 1,422% in Maine, and 3272% in New Hampshire during that period, according to CDC data.

Historically, Babesiosis wasn’t considered to be endemic in those states. But it is now, the federal health agency said in a report, which called on public health workers to draw attention to the disease, how to recognize it, and how to prevent it.

What is babesiosis?

It’s a disease caused by microscopic parasites that infect red blood cells. Those parasites are usually carried by ticks, white-footed mice, and other small mammals, according to the CDC.

What are the symptoms of babesiosis?

The disease can cause a wide range of illness, from no symptoms at all to death. The most common symptoms, however, include:

• fever
• muscle and joint pain
• headache

 More severe symptoms may include:

• kidney failure
• low blood platelet count
• acute respiratory distress syndrome, in which blood oxygen levels dip dangerously low

How does someone catch babesiosis?

Babesiosis is usually spread by black-legged or deer ticks—particularly young ticks in the nymph stage. Nymphs are usually found during spring and summer in areas with woods, brush, or grass. Some nymphs are as small as a poppy seed, so you may not realize you’ve been bitten. That’s why it’s important to check daily for ticks if you’ve visited a high-risk area.

It’s also possible to contract Babesiosis through an infusion of contaminated blood, or through childbirth (a mother may pass it on to her child).

Who is most in danger of becoming seriously ill with babesiosis?

Those at high risk of severe illness and death include:

• the immunocompromised (perhaps due to cancer or AIDS)
• those who don’t have a spleen
• those with serious health conditions like liver or kidney disease
• the elderly

What states I am most likely to catch babesiosis in?

Until now, babesiosis was considered endemic in only seven states, according to the CDC: 

• Connecticut
• Massachusetts
• Minnesota
• New Jersey
• New York
• Rhode Island
• Wisconsin

Previous studies have noted increasing reports of babesiosis in particular areas of the U.S., including New York from 2011 to 2015. Cases reported by the state to the CDC rose nearly 60% from 2011 to 2019, according to federal health data. What’s more, New York reported the largest number of cases among all states that reported during that time period.

How can I prevent babesiosis?

People spending time outdoors in states where Babeiosis is endemic—and in bordering states—should do the following, according to the CDC:

• Avoid tick-infested areas.
• Wear long pants.
• Steer clear of underbrush and long grass.
• Use tick repellent.
• Check for ticks daily.