Cases of a tick-borne illness known as babesiosis are becoming much more common in the United States, according to a new report from the Centers for Disease Control and Prevention (CDC). Babesiosis is transmitted by blacklegged ticks, also called deer ticks, and can cause flu-like symptoms in some people and potentially fatal infections in others.
Until recently, babesiosis was relatively rare, the CDC said. But in 10 states, up from seven states roughly a decade ago, babesiosis is now considered endemic — meaning it’s a disease outbreak that’s a constant, ongoing threat.
“This marks an unfortunate milestone in the emergence of babesiosis in the U.S.,” says Peter Krause, MD, a senior research scientist at the Yale School of Public Health in New Haven, Connecticut, who wasn’t involved in the CDC report. “It is concerning because this disease can be serious or life threatening in immunocompromised individuals.”
Babesiosis Is Spreading West and South, Too
The CDC reported that babesiosis cases more than doubled from 2011 to 2019, reaching endemic levels for the first time in Maine, New Hampshire, and Vermont. Babesiosis was already at endemic levels in seven states: Connecticut, Massachusetts, Minnesota, New Jersey, New York, Rhode Island, and Wisconsin.
Nine other states that previously had no cases at all or only rarely recorded babesiosis cases are now seeing more instances of this illness, even though case levels are still considered low, the CDC reported. These states include Delaware, Illinois, Iowa, Maryland, North Dakota, Ohio, South Dakota, Virginia, and West Virginia.
Why Are Cases of Babesiosis on the Rise?
Several factors are making babesiosis more common, Dr. Krause says. One culprit is global warming and increased precipitation, which are helping to expand the blacklegged tick population. Increases in the white-tailed deer population, a common source of food for ticks, are also contributing, Krause says. An aging population is also leading to increased caseloads, with elderly people more vulnerable to infections as well as more homes being built in areas closer in proximity to ticks.
Most cases of babesiosis in the United States are caused by bites from blacklegged deer ticks, Ixodes scapularis, in Northeastern and Midwestern states, the CDC said. The same ticks can also transmit Lyme disease. Babesiosis can also spread through blood transfusions, organs transplanted from infected donors, or from infected pregnant parents to their babies.
Even though most cases aren’t caused by blood transfusions, people who acquire babesiosis through contaminated blood have significantly worse outcomes and a higher risk of death than people who get it from tick bites, the CDC said. U.S. regulators already recommend screening donor blood for babesiosis in 14 states and Washington, DC, according to the CDC, and regulators continue to evaluate whether screening may be needed in additional states.
Symptoms, Testing, and Treatment for Babesiosis
Babesiosis symptoms can start within a week of exposure and may continue to develop over several weeks or months, according to the CDC. Many people experience no symptoms at all, but some individuals can develop flu-like symptoms including fever, chills, sweats, headache, body aches, loss of appetite, nausea, and fatigue. Because the parasite that causes babesiosis infects red blood cells, this illness can also cause anemia.
Babesiosis can be severe or even fatal for certain groups, including individuals who are elderly, have a weakened immune system, or are living with serious chronic health conditions like kidney or liver disease, the CDC says.
Babesiosis can be detected with a blood test, and it can be treated with antibiotics. “Fortunately, prompt diagnosis and treatment will lead to cure without complications for most infected people,” Krause says.
How Can I Prevent Deer Tick Bites and Infection?
Babesiosis can be prevented in many cases by taking precautions when you spend time outdoors, says Bobbi Pritt, MD, MSc, a tick-borne illness researcher and chair of clinical microbiology at Mayo Clinic in Rochester, Minnesota.
“The best way to prevent babesiosis and other tick-borne diseases is to avoid tick bites,” Dr. Pritt says. “This can be done by avoiding areas where ticks are found such as tall grasses, using tick repellent, and covering exposed skin with clothing.”
The CDC also recommends several other ways to keep ticks off your body when you spend time outdoors. These include:
- Watch where you walk. Stick to cleared trails, and try to steer clear of overgrown grasses, leaf piles, and brush where ticks tend to be found.
- Cover your skin. Wear long pants, long sleeves, tall socks, and tuck everything in so ticks can’t easily crawl inside your clothing.
- Use tick repellent. Apply products containing DEET directly to clothing or skin. Products containing permethrin can also be applied to clothing, but not to skin.
When you’re done outside, daily tick checks are essential. Ticks need to stay attached to a person for more than 36 hours to be able to spread the parasite that causes babesiosis, according to the CDC.
How to Check for Ticks — and Why It’s Essential
This is the best way to check for ticks, according to the CDC:
- Remove ticks from clothing and pets before you get inside.
- Use a mirror to inspect every part of your body, including around the groin, between toes, behind the ears, and in and around your hair.
- Remove ticks with pointed, fine-tipped tweezers.
“People should take tick-borne diseases seriously and protect themselves from tick bites,” Pritt says. “However, they shouldn’t stop doing things that they enjoy outdoors, since there are a lot of health benefits from being active and enjoying nature. By following simple steps such as using tick repellent and performing frequent tick checks, people can greatly reduce their risk of tick-borne disease.”