Babesia vs Malaria: Two Travelers Misdiagnosed After U.S. Travel
Babesia can mimic malaria in returning travelers
Travel history may change the diagnosis
Delayed recognition can affect treatment decisions
I discuss two travelers diagnosed with Babesia after returning from the United States during this episode of the Inside Lyme podcast series.
Kwon and colleagues described two women from South Korea who contracted Babesia infections while visiting the United States. Their cases illustrate how babesiosis may be overlooked when clinicians focus primarily on malaria in returning travelers.1
The cases, published in the Korean Journal of Parasitology, highlight how travel history and blood smear interpretation can alter diagnosis and treatment decisions.
Babesia vs malaria: Why are they confused?
Both infections invade red blood cells and may cause fever, anemia, thrombocytopenia, fatigue, and abnormal blood smear findings, making the distinction between Babesia vs malaria challenging in returning travelers.
This overlap explains why babesiosis is sometimes initially mistaken for malaria, particularly in countries where malaria remains more familiar to clinicians.
Search interest around “babesia vs malaria” and “babesiosis mimics malaria” reflects this diagnostic challenge.
The first traveler: Babesia mistaken for malaria
The first patient was a 50-year-old woman admitted with fever, abdominal pain, and nausea after visiting a forested region of New Jersey four weeks earlier.
She recalled a skin lesion on her calf followed by headache, muscle soreness, fever, and chills.
Because malaria remains endemic in northern South Korea, physicians initially suspected malaria. Her blood smear appeared suspicious for Plasmodium, and splenic infarction further complicated the picture.
She was initially treated with hydroxychloroquine for presumed malaria.
Subsequent testing did not support malaria.
Physicians re-reviewed her blood smear and identified tetrad structures resembling the Maltese cross associated with Babesia. PCR testing later confirmed Babesia infection.1
Babesia microti is transmitted by the same deer tick associated with Lyme disease and may occur alongside coinfections.
Once appropriate therapy was started, her symptoms and laboratory abnormalities improved rapidly.
The second traveler: Severe babesiosis mistaken for malaria
The second patient was a 72-year-old woman admitted with fever, anemia, thrombocytopenia, and elevated inflammatory markers.
Her blood smear again suggested malaria-like organisms, but malaria antigen testing was negative.
Further review identified Maltese cross forms in red blood cells similar to those observed in the first patient.1
Initial treatment included atovaquone/proguanil and azithromycin.
Despite therapy, her condition worsened with pulmonary congestion and progressive illness.
Treatment was changed to quinine plus clindamycin, a regimen historically used for severe babesiosis.
She underwent exchange transfusion because of disease severity.
Respiratory failure later required intubation.
Doxycycline was added because physicians suspected additional tick-borne infections.
Subsequent testing confirmed concurrent Lyme disease with positive IgM and IgG Western blot testing.1
She died 31 days after hospital admission despite aggressive treatment.
What is the Maltese cross in Babesia?
The Maltese cross refers to tetrad formations seen inside red blood cells and is considered an important clue favoring babesiosis rather than malaria.
Search queries around “Maltese cross malaria” likely reflect attempts to distinguish Babesia from malaria on blood smear review.
Clinical lessons from these cases
- Babesiosis may mimic malaria.
- Travel history can change the differential diagnosis.
- Blood smear interpretation remains critical.
- Coinfections may complicate management.
- Delayed diagnosis may worsen outcomes.
Frequently Asked Questions
Can Babesia be mistaken for malaria?
Yes. Both diseases infect red blood cells and may produce similar symptoms and blood smear findings.
What is the Maltese cross in babesiosis?
The Maltese cross is a tetrad formation inside red blood cells that supports a diagnosis of babesiosis.
Can Babesia and Lyme disease occur together?
Yes. The same tick species can transmit both infections.
Why does travel history matter?
Travel history changes diagnostic thinking and may help clinicians recognize imported tick-borne illnesses.
Clinical Takeaway
Babesia vs malaria remains an important diagnostic challenge because both illnesses share overlapping clinical and laboratory features.
Travel history, recognition of Maltese cross formations, and awareness of coinfections remain critical when evaluating unexplained fever and anemia.
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References
- Kwon HY, Im JH, Park YK, Durey A, Lee JS, Baek JH. Two Imported Cases of Babesiosis with Complication or Co-Infection with Lyme Disease in Republic of Korea. Korean J Parasitol. 2018;56(6):609-613.
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
Is there any cure for Babesia?
I start with Malarone and Zithromax I have more recently prescribed tafenoquine https://danielcameronmd.com/treatment-relapsing-babesia/ I have patients do well. Some relapse
I have found Malarone and Zithromax helpful I sometimes have to add other medications ie tafenoquine https://danielcameronmd.com/treatment-relapsing-babesia/. Some relapse