Babesia travel cases are rising globally as international travelers carry tick-borne infections across borders. “Recently, sporadic cases of human babesiosis caused by several species of Babesia have been reported in other countries,” write the authors of “Imported Human Babesiosis, Singapore, 2018.”
These imported cases include:
- Babesia microti (Germany, Australia, South Korea)
- Babesia microti-like (Japan, Taiwan, China)
- Babesia duncani (United States, Canada)
- Babesia divergens (Europe)
- Babesia venatorum (Europe, China)
- Babesia crassa-like (China)
- Babesia motasi-like (South Korea)
Early Babesia Travel Cases
In 2003, Nohýnková and colleagues reported what was believed to be the first case of symptomatic Babesia microti infection imported into the Czech Republic from the United States. Meanwhile in 2013, investigators described the “first human case of Babesia microti infection imported to Denmark from the United States by a 64-year-old female traveler with fever of unknown origin.”
According to the authors, “The case raises the possibility that Babesia infections may be under-diagnosed, [and] illustrates the importance of a thorough travel history…”
The number of international travelers carrying tick-borne diseases into foreign countries is rising, making it increasingly important for clinicians to gather a thorough travel history on patients.
Two recent case reports demonstrate the rise of babesia travel cases and highlight the challenges clinicians face in distinguishing these infections from malaria.
Case 1: Babesia Travel from US to Singapore
A 37-year-old man traveled to multiple places in the year before his illness. His travel history included Vietnam, Thailand, Indonesia, Cambodia, and the United States.
On June 17, 2018, after visiting the Northeastern USA, he noted a right ankle papule that lasted 3 weeks. “He sought consultation at a travel clinic [in Singapore] because of high fever (104°F), rigors, and headaches, which had persisted and worsened over 18 days,” writes Lim and colleagues.
Doctors had prescribed amoxicillin, but the symptoms persisted.
“Laboratory test results revealed moderate thrombocytopenia and anemia, and malaria blood films revealed trophozoites forming in erythrocytes, suggestive of Babesia,” writes Lim.
The doctors confirmed the diagnosis of Babesia microti with additional testing. He was treated successfully with quinine and clindamycin.
Case 2: Babesia Travel from US to Spain
“A 72-year-old man with a 15-day history of fever, generalized arthralgia, asthenia, and decreased appetite was admitted to Hospital Universitario San Cecilio, Granada, Spain,” writes Guirao-Arrabal and colleagues in “Imported babesiosis caused by Babesia microti—A case report.”
The man had a history of sweating and his inflammatory markers were elevated. He also had a history of type 2 diabetes.
He reportedly traveled to a park in Westchester County, NY, an area that is considered endemic for babesiosis.
Malaria was considered based on intraerythrocytic forms in the red cells. The malaria antigen and PCR tests for malaria were negative.
Babesia microti was presumed with a low level of parasitemia (0.5%). There was no evidence of another tick-borne illness. After treatment with atovaquone and azithromycin, his parasitemia resolved.
Why Babesia Travel Cases Are Missed
The challenge with babesia travel cases is that clinicians outside endemic areas may not recognize the infection. Babesia can look like malaria on blood smear, but malaria tests come back negative—leaving doctors puzzled.
A thorough travel history is essential. Patients who have visited the Northeastern United States—particularly Massachusetts, Rhode Island, Connecticut, New York, and New Jersey—should be evaluated for Babesia if they present with:
- Unexplained fever
- Thrombocytopenia
- Anemia
- Negative malaria tests despite parasites on blood smear
This pattern also applies to tourists visiting the US who develop symptoms after returning home.
Editor’s Note
It is encouraging to see that Babesia is now being considered by clinicians and treated appropriately—even in countries where the infection is not endemic. As babesia travel cases continue to rise, awareness will be critical for timely diagnosis.
Frequently Asked Questions
Can you get Babesia while traveling?
Yes. Babesia travel cases occur when people visit endemic areas like the Northeastern United States and bring the infection home. Symptoms may not appear until weeks after the trip.
Why is Babesia confused with malaria?
Both infections show parasites inside red blood cells on blood smear. Clinicians in non-endemic areas may assume malaria first—but when malaria tests are negative, Babesia should be considered.
Which countries have reported imported Babesia cases?
Cases have been imported to Singapore, Spain, Denmark, Czech Republic, Germany, Australia, South Korea, and other countries—typically from travelers returning from the United States.
What should doctors ask about travel history?
Doctors should ask if patients have visited the Northeastern US, spent time outdoors in wooded or grassy areas, or noticed any tick bites or unexplained rashes in the weeks before symptoms began.
How is Babesia treated in travelers?
Standard treatment is atovaquone and azithromycin, or quinine and clindamycin. Both cases described here resolved with appropriate treatment once the diagnosis was made.
References
- Lim PL, et al. Imported Human Babesiosis, Singapore, 2018. Emerg Infect Dis. 2020.
- Nohýnková E, et al. First case of symptomatic Babesia microti infection imported into the Czech Republic from the United States. Emerg Infect Dis. 2003.
- Hildebrandt A, et al. First confirmed autochthonous case of human Babesia microti infection in Europe. Eur J Clin Microbiol Infect Dis. 2007.
- Guirao-Arrabal E, et al. Imported babesiosis caused by Babesia microti—A case report. Travel Med Infect Dis. 2020.
