Imported Babesiosis or Malaria? Why Babesia Gets Missed
Imported babesiosis can resemble malaria
Travel history may change the diagnosis
Babesia microti cases are being reported worldwide
“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.” [1]
These imported Babesia 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)
Additionally, 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. [2]
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.” [3]
READ MORE: Tourists visiting the United States contract Babesia, leaving one dead
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…” [3]
[bctt tweet=”Imported babesiosis can resemble malaria, making travel history essential when evaluating fever, anemia, and parasitemia.” username=”DrDanielCameron”]
Why imported babesiosis is often mistaken for malaria
Two recent case reports demonstrate the rise of tick-borne diseases being imported into other countries and highlight the challenges clinicians face distinguishing Babesia microti from malaria.
Case 1: Singapore traveler diagnosed with Babesia microti
A 37-year-old man traveled to multiple locations during 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 United States, 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,” write Lim and colleagues. [1]
Doctors initially prescribed amoxicillin, but symptoms persisted.
LISTEN TO PODCAST: Babesia treatment of two travelers
“Laboratory test results revealed moderate thrombocytopenia and anemia, and malaria blood films revealed trophozoites forming in erythrocytes, suggestive of Babesia,” the authors explain.
Additional testing confirmed Babesia microti. He improved following treatment with quinine and clindamycin.
Case 2: Imported babesiosis diagnosed in 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,” write Guirao-Arrabal and colleagues. [4]
The patient reported sweating episodes and elevated inflammatory markers. He also had type 2 diabetes.
He had traveled to Westchester County, NY, an area endemic for babesiosis.
Malaria was initially considered because intraerythrocytic forms were observed on blood smear. However, malaria antigen and PCR testing were negative.
Babesia microti infection was presumed with low-level parasitemia (0.5%). There was no evidence of another tick-borne illness.
Following treatment with atovaquone and azithromycin, parasitemia resolved.
Why travel history matters when evaluating fever after travel
These reports highlight the importance of obtaining a travel history in patients with fever, anemia, thrombocytopenia, or parasites identified on blood smears.
Babesiosis can resemble malaria clinically and microscopically, increasing the risk of delayed diagnosis—particularly outside endemic regions.
Frequently Asked Questions
Can babesiosis be mistaken for malaria?
Yes. Babesiosis and malaria may both appear as parasites inside red blood cells and can share symptoms including fever, chills, anemia, and sweats.
Why is travel history important in babesiosis?
Travel history can identify exposure to endemic areas and may help clinicians consider tick-borne illnesses when malaria testing is negative.
Can Babesia infections occur outside endemic regions?
Yes. Imported cases have been reported in multiple countries after travelers returned from endemic regions.
Clinical Takeaway
Imported babesiosis appears to be increasingly recognized worldwide. Clinicians evaluating travelers with fever, anemia, thrombocytopenia, or suspected malaria should consider Babesia infection, particularly after travel to endemic areas.
Travel history may provide the clue that distinguishes imported babesiosis from malaria.
Related Articles
Tourists visiting the United States contract Babesia, leaving one dead
Babesia symptoms, diagnosis, and treatment
Coinfections and tick-borne illnesses
Babesia treatment of two travelers
References
- Lim S, Lim K, Yong E, et al. Imported Human Babesiosis, Singapore, 2018. Emerg Infect Dis. 2020.
- Nohýnková E, Kubek J, Měšťánková O, Chalupa P, Hubálek Z. A case of Babesia microti infection imported into the Czech Republic from the USA. Cas Lek Cesk. 2003;142:377–381.
- Holler JG, Röser D, Nielsen HV, Eickhardt S, Chen M, Lester A, Bang D, Frandsen C, David KP. A case of human babesiosis in Denmark. Travel Med Infect Dis. 2013 Sep-Oct;11(5):324-328.
- Guirao-Arrabal E, et al. Imported babesiosis caused by Babesia microti − A case report. Travel Med Infect Dis. 2021.
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention
