Babesiosis, a tickborne disease sometimes called “American malaria,” is rising sharply in the U.S., new research showed

Why You Need to Know About 'American Malaria,' a Tickborne Disease Rising Across the US Experts explain the increase and advise people in babesiosis-endemic regions to take precautions to prevent tick bites

Babesiosis, a tickborne disease sometimes called “American malaria,” is rising sharply in the U.S., new research showed

• Babesiosis, a tickborne disease with symptoms similar to those seen in malaria, is rising sharply in the U.S., new research showed.
• The study also found that 42% of people diagnosed with babesiosis also had one or more additional tickborne infections, like Lyme disease.
• Researchers say the geographic range of infected ticks is a major driver of the babesiosis increase and advise people in newly endemic areas to take precautions to prevent tick bites.

A tickborne disease called babesiosis is rising sharply in the United States, according to a new study.

The research, published in Open Forum Infectious Diseases, looked at a nationally representative sample of about 3,500 Americans with babesiosis, which is often called "American malaria" because—like malaria—it's caused by a parasite that affects red blood cells. They found that case rates increased 9% per year from 2015 to 2022, the timeframe studied. 

Though babesiosis is still relatively rare, the uptick should lead people to be extra cautious when outdoors regardless of where they live, Paddy Ssentongo, MD, PhD, a study author and an assistant professor in the Department of Public Health Sciences at Penn State, told Health. “Our findings call for the general public—particularly those living in the U.S. babesiosis and Lyme disease-endemic regions—to take tick prevention precautions seriously,” Ssentongo said.

Additionally, healthcare providers should consider the possibility that people presenting with flu-like symptoms, such as fever and chills, could have the disease even if they have no knowledge of a tick bite.

What Is Babesiosis—and Why Are Case Rates Increasing?

Babesiosis is a disease caused by microscopic parasites that spread through the bite of an infected deer tick, Brian Labus, PhD, MPH, an expert in infectious diseases and an assistant professor in the Department of Epidemiology and Biostatistics at the University of Nevada, Las Vegas, School of Public Health, told Health.

The same type of tick causes other tickborne illnesses, which the new study also found in 42% of people with babesiosis. Within that group, 41% also had Lyme disease, almost 4% had ehrlichiosis, and a tiny portion, 0.3%, had anaplasmosis. (The good news: The study also found that people with babesiosis and another tickborne disease aren’t more likely to die than those with babesiosis alone.)

There’s also a small risk of acquiring babesiosis through a blood transfusion in areas where the disease is common, Labus added. But “the disease cannot spread from person to person,” he said.

The uptick in case rates is partially due to the geographic range of infected ticks increasing and putting more people at risk, Labus said.

A CDC report from 2023 found that babesiosis is now considered endemic (meaning regularly occurring) in Maine, New Hampshire, and Vermont in addition to the seven states in which it was previously known to be endemic: Connecticut, Massachusetts, Minnesota, New Jersey, New York, Rhode Island, and Wisconsin.

“There are a variety of factors, including land use change, climate change, changes in wildlife populations, and changes in human behavior that have contributed to the blacklegged tick’s ability to spread into new regions,” Griffin Dill, PhD, manager of the Tick Lab within the Diagnostic and Research Laboratory at the University of Maine, previously told Health.

Babesiosis is also underdiagnosed and underreported, Labus added, though clinicians have become better at identifying it as it has become more common.

“These two factors are why we have been seeing increases in babesiosis and other tick-borne diseases for the past two decades,” he said.

Labus noted that even if the number of people infected every year stops increasing, we are likely to continue seeing increasing numbers because of improvements in awareness and diagnosis.

Symptoms and Diagnosis

Once infected, some people may not show any symptoms, while after one to four weeks, others may report symptoms similar to those seen in malaria, like fever, fatigue, sweats, nausea, and malaise. 

“The parasite reproduces in the red blood cells, which can destroy them and cause anemia,” Labus said.

The disease can be dangerous for some, particularly immunocompromised people or those over 50. It can cause serious problems such as pulmonary edema, congestive heart failure, renal failure, a ruptured spleen, or a coma.

“We [also] worry that little is known regarding the long-term sequelae of the disease,” Ssentongo said. “Many unanswered questions also exist, such as the long-term effects on the brain.”

A blood test can reveal if someone has babesiosis. “If a doctor suspects the disease based on a history of fevers and anemia, the blood can be observed under a microscope to identify the parasite, or can be tested to identify the genetic material of the organism by PCR or through tests to identify the body’s immune response to infection,” Labus said.

Once diagnosed, doctors treat the disease with a combination of two antimicrobial agents given over seven to 10 days. “People with recurring disease or who are immunocompromised may need to be treated for several weeks,” Labus added.

What to Expect

As the climate changes, ticks’ range can change or increase, bringing tickborne diseases like babesiosis to new places and people, Labus explained. “We will likely see clusters of disease in these new areas, as people living there haven’t previously thought about tickborne diseases and won’t be doing anything to protect themselves,” he said.

Diagnosing tickborne diseases can sometimes be challenging for clinicians, especially in areas where they are uncommon, Labus added. “[Healthcare providers] will have to consider diseases they previously hadn’t considered in the past when evaluating patients in these newly endemic areas,” he said.

The predicted rise in widespread infection has multiple consequences, Ssentongo explained. “This increase in temporal and geographic spread will translate to an increase in healthcare costs and disability-adjusted life years, also known as disease burden,” he said.

That’s why experts stress the importance of staying vigilant when it comes to protecting yourself from tick bites. 

“People who live, work, and travel to endemic areas need to be aware of illnesses like this and the precautions they should take to avoid infection,” S. Wesley Long, MD, PhD, an associate professor of pathology and genomic medicine at Houston Methodist Weill Cornell Medical College, told Health.

According to Ssentongo, precautions “include using tick repellent before hiking, wearing long pants and long-sleeved shirts when walking in the underbrush, wooded, or forested areas, and checking for ticks immediately after being outdoors."

This story originally appeared on: Health News - Author:Sherri Gordon