Treatment for Relapsing Babesiosis?


Babesiosis can present with a variety of symptoms ranging from asymptomatic disease to severe symptoms, resulting in death. The tick-borne illness can be transmitted through the bite of an infected black-legged tick or unknowingly through a tainted blood transfusion.

As this case report demonstrates, immunocompromised patients with Babesia may not respond to standard antimicrobial treatment, resulting in relapsing babesiosis. But investigators suggest that a combination of medications including Malarone shows promise for treatment-resistant patients.

In their article “Atovaquone-Proguanil: A Promising Therapy for Persistent Relapsing Babesiosis,” Shahid and colleagues describe a case of relapsing babesiosis in an immunocompromised patient which was treated successfully with Malarone.¹

“Atovaquone-proguanil (Malarone) is a novel therapy that can be used as part of a salvage regimen in case antimicrobial resistance or failure exists,” the authors state.

Case report: Treatment for Relapsing Babesiosis

A 73-year-old man, with a history of chronic lymphocytic leukemia (CLL) in complete remission, presented to his physician with generalized weakness and fatigue.

“His laboratory work on this admission noted unexplained anemia,” the authors state.

Several weeks later, he exhibited confusion and falls and was referred to a hematology clinic where he began prednisone therapy. The man was eventually admitted to the hospital for ongoing symptoms.

Interestingly, he did not have night sweats, fever, or chills, often seen in patients with Babesia.

And although he was outdoors frequently, as an avid fisherman and hunter, he did not recall having a tick bite. However, he did have multiple blood transfusions to treat his anemia.

“He reported a recent trip to Long Island, New York, in August, but denied any known recent illnesses or exposure.”

The patient began treatment with steroids and intravenous immunoglobulins (IVIGs) and rituximab for suspected CLL or acute viral illness. And, his symptoms improved slightly.

However, several weeks later, he developed severe fatigue and shortness of breath.

The patient’s tick-borne disease antibody panel was consistent with Babesia microti infection.

“A bone marrow biopsy was performed which noted hemophagocytosis,” the authors state. “Initial review of the peripheral blood smear showed ring forms suggestive of a parasitic infection suspicious for malaria.”

Multiple Babesiosis treatments

The patient was initially treated with atovaquone and azithromycin for 4 weeks.

However, 8 weeks after completing treatment, he presented again with severe generalized weakness and easy fatigability.

He began a new treatment regimen with azithromycin, atovaquone, and clindamycin for 8 weeks.

During his last week of therapy, he developed the same symptoms of generalized weakness.  And, once again, a peripheral smear showed relapsing babesiosis.

Treatment success with drug combination

Treatment was switched again. And the patient was prescribed atovaquone proguanil (Malarone), azithromycin, and clindamycin.

For the next year, all follow-up peripheral smears revealed no relapse of babesiosis.

  1. Shahid M, Wechsler B, Parameswaran V, Diaz MA. Atovaquone-Proguanil: A Promising Therapy for Persistent Relapsing Babesiosis. Case Rep Infect Dis. 2024 May 14;2024:7168928. doi: 10.1155/2024/7168928. PMID: 38774593; PMCID: PMC11108688.

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