Relapsing Babesiosis Treatment: Can Malarone Help?
Relapsing babesiosis may not respond to standard treatment
Malarone showed promise in one treatment-resistant case
Immunocompromised patients may require longer monitoring
Relapsing babesiosis treatment can be challenging, particularly in immunocompromised patients who do not respond fully to standard antimicrobial therapy.
Babesiosis is a tick-borne infection caused by Babesia, a parasite that infects red blood cells. In some patients, especially those with immune suppression, infection may persist or relapse after treatment.
In their article “Atovaquone-Proguanil: A Promising Therapy for Persistent Relapsing Babesiosis,” Shahid and colleagues describe an immunocompromised patient with relapsing babesiosis who was treated successfully with atovaquone-proguanil, also known as Malarone.
The authors state that atovaquone-proguanil may be considered as part of a salvage regimen when antimicrobial resistance or treatment failure is suspected.
Case report: relapsing babesiosis treatment in an immunocompromised patient
A 73-year-old man with a history of chronic lymphocytic leukemia (CLL), in complete remission, presented with generalized weakness and fatigue.
His laboratory work showed unexplained anemia.
Several weeks later, he developed confusion and falls and was referred to a hematology clinic, where he began prednisone therapy. He was later admitted to the hospital for persistent symptoms.
Interestingly, he did not have night sweats, fever, or chills, which are often seen in patients with Babesia. Patients with tick-borne infections may still have atypical presentations, and symptoms such as night sweats may be absent even in significant illness.
Although he spent time outdoors as an avid fisherman and hunter, he did not recall a tick bite. He also had multiple blood transfusions to treat his anemia, which is clinically relevant because Babesia can be transmitted by ticks and, in some cases, through transfusion.
He reported a recent trip to Long Island, New York, but denied known recent illness or exposure.
The patient was treated with steroids, intravenous immunoglobulin, and rituximab for suspected CLL-related or viral illness. His symptoms improved slightly.
However, several weeks later, he developed severe fatigue and shortness of breath.
Babesia diagnosis after worsening symptoms
The patient’s tick-borne disease antibody panel was consistent with Babesia microti infection.
A bone marrow biopsy showed hemophagocytosis. Initial review of the peripheral blood smear showed ring forms suggestive of a parasitic infection and initially suspicious for malaria.
This case highlights how tick-borne coinfections may be difficult to recognize when symptoms overlap with hematologic disease, immune suppression, anemia, or other systemic illness.
Multiple babesiosis treatments were attempted
The patient was initially treated with atovaquone and azithromycin for 4 weeks.
However, 8 weeks after completing treatment, he again presented with severe generalized weakness and easy fatigability.
He then began a new treatment regimen with azithromycin, atovaquone, and clindamycin for 8 weeks.
During the last week of therapy, he developed the same generalized weakness. Once again, a peripheral smear showed relapsing babesiosis.
Malarone for Babesia after treatment failure
Treatment was changed again. The patient was prescribed atovaquone-proguanil (Malarone), azithromycin, and clindamycin.
For the next year, follow-up peripheral smears showed no relapse of babesiosis.
This case does not prove that Malarone alone was responsible for the outcome, but it suggests that atovaquone-proguanil may have a role in selected patients with persistent or relapsing babesiosis when standard treatment fails.
Patients with relapsing Babesia may need individualized evaluation, especially when immune suppression, transfusion exposure, persistent anemia, or repeated positive smears are present.
Could newer therapies such as tafenoquine play a role?
Tafenoquine has emerged as another potential option being explored for difficult or relapsing Babesia infections, particularly in selected patients who fail standard therapy.
Evidence remains limited, and most reports involve case series or difficult-to-treat patients rather than large clinical trials.
Additional studies are needed to determine where tafenoquine fits among therapies for persistent or relapsing babesiosis.
What are the limitations of this case report?
- This is a single patient case report
- Immunocompromised patients may respond differently than typical patients
- The report cannot prove that Malarone alone explained treatment success
- Case reports cannot establish treatment effectiveness for broader populations
- Longer follow-up studies are needed to determine optimal therapy for relapsing babesiosis
Frequently Asked Questions
What is relapsing babesiosis?
Relapsing babesiosis occurs when Babesia infection returns or persists after treatment, sometimes with recurrent symptoms and positive blood smear findings.
Can Malarone treat Babesia?
Malarone, which contains atovaquone-proguanil, was used successfully as part of a combination salvage regimen in this case report of relapsing babesiosis.
Is tafenoquine used for relapsing babesiosis?
Tafenoquine has been explored in selected difficult-to-treat Babesia cases, but evidence remains limited and its role continues to evolve.
Why does babesiosis relapse?
Relapse may occur in patients with immune suppression, persistent parasitemia, treatment failure, antimicrobial resistance, or difficulty clearing infection.
How long is Babesia treatment?
Treatment length varies depending on severity, immune status, response to therapy, and whether relapse occurs. Immunocompromised patients may require longer monitoring and individualized treatment.
Can Babesia relapse after treatment?
Yes. This case report describes relapse after standard therapy, followed by successful suppression of relapse after a combination regimen that included Malarone.
Clinical Takeaway
Relapsing babesiosis treatment can be difficult in immunocompromised patients, particularly when symptoms return after standard atovaquone and azithromycin therapy.
This case suggests that Malarone may have a role in selected treatment-resistant Babesia cases, while newer therapies such as tafenoquine continue to be evaluated.
Related Articles
These articles explore Babesia transmission, neurologic complications, transfusion-associated infection, diagnostic delays, and overlapping tick-borne illnesses.
How long does it take for a tick to transmit Babesia?
Neurologic complications of Babesia
Patient contracts Babesia from a blood donor
Delayed Lyme disease diagnosis
Lyme disease misdiagnosis
References
- Shahid M, Wechsler B, Parameswaran V, Diaz MA. Atovaquone-Proguanil: A Promising Therapy for Persistent Relapsing Babesiosis. Case Rep Infect Dis. 2024;2024:7168928.
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
