Can Babesia Become Chronic? A Case of Treatment Failure
Persistent Babesia infection can occur in immunocompromised patients
Relapsing parasitemia may require prolonged combination therapy
This case highlights the potential and limitations of tafenoquine
Can Babesia become chronic? Although most patients recover after standard treatment, persistent or relapsing Babesia microti infection can occur in individuals with impaired immune function. This case report describes an immunocompromised woman with recurrent babesiosis despite multiple treatment regimens, including off-label tafenoquine, illustrating the challenges of treating persistent or chronic Babesia infection in immunocompromised patients.
In the article “Failure of an Approximately Six Week Course of Tafenoquine to Completely Eradicate Babesia microti Infection in an Immunocompromised Patient,” Prasad and Wormser describe a chronic relapsing Babesia infection in an elderly woman.1
Can Babesia become chronic?
Persistent or chronic babesiosis is uncommon in immunocompetent individuals but is well recognized in patients with impaired immunity. Risk factors include hematologic malignancies, immunosuppressive medications, asplenia, and therapies that impair B-cell function. These patients may experience recurrent parasitemia, ongoing hemolysis, and repeated relapses despite apparently successful initial treatment.
The 74-year-old patient was admitted to the hospital in August 2021 with a 2-day history of fatigue and fevers. She was immunocompromised and had a history of diffuse large B-cell lymphoma treated with chemotherapy, polymyalgia rheumatica treated with low-dose steroids (prednisone 5 mg/day plus a short trial of tocilizumab), and cold autoimmune hemolytic anemia.
“A peripheral blood smear was positive for B. microti (0.2% parasitemia),” according to the authors. Her hemoglobin dropped as low as 6.5 g/dL, requiring transfusion of 10 units of packed red blood cells.
She was initially treated with a 7-day course of azithromycin and atovaquone. She also received corticosteroids, and her parasitemia resolved.
However, the woman later developed recurrent fatigue and fever accompanied by recurrent parasitemia (0.3%), indicating persistent infection despite initial treatment.
Why did Babesia treatment fail?
The clinicians planned to retreat her with a 6-week course of azithromycin and atovaquone but added clindamycin because of persistent parasitemia and fatigue. She was subsequently switched to quinine plus oral clindamycin.
READ MORE: Tafenoquine: Treatment for Relapsing Babesia
“This antiparasitic drug regimen was discontinued on 20 January 2022, because she developed symptoms consistent with cinchonism (hearing loss, vertigo, tinnitus),” wrote the authors.
Her cinchonism resolved after discontinuation of quinine and clindamycin.
“She then developed severe fatigue and subjective fevers on 22 February 2022 with a recurrence of the Babesia parasitemia (<0.1%), along with evidence of worsening hemolysis,” wrote the authors.
She was retreated with oral clindamycin together with a reduced dose of quinine. Despite therapy, low-level parasitemia persisted.
How was tafenoquine used?
The woman was then prescribed off-label tafenoquine after testing negative for glucose-6-phosphate dehydrogenase (G6PD) deficiency, an important safety requirement before initiating therapy.
“She was started on oral tafenoquine 200 mg once a day for 3 days (loading dose) from 7–9 March 2022, and then 200 mg once per week thereafter starting on 16 March 2022,” wrote the authors.
During treatment, her hemoglobin improved dramatically from 6.5 g/dL to 13.3 g/dL without requiring additional blood transfusions, suggesting improved control of the hemolytic process.
However, tafenoquine was discontinued after approximately six weeks because of neutropenia. “The neutrophil count reached a nadir level of 325 cells/uL,” the authors reported.
What happened after tafenoquine?
Following discontinuation of tafenoquine, the patient’s severe fatigue returned. Laboratory testing again demonstrated recurrent hemolysis and low-level Babesia parasitemia (<0.1%), indicating that the infection had not been completely eradicated.
“She was started on a new drug regimen of oral azithromycin 1000 mg once daily, atovaquone liquid suspension 750 mg once daily, and four Malarone® tablets once daily (each tablet consisting of 250 mg atovaquone plus 100 mg of proguanil) on 2 June 2022,” wrote the authors.
By the end of June, PCR testing for Babesia was negative.
However, “It was planned to continue treatment for at least 12 weeks,” wrote the authors, “and even to consider chronic suppressive therapy going forward.”
Prasad and colleagues also discussed two previously published cases in which tafenoquine appeared to successfully treat relapsing Babesia, emphasizing that experience with the drug remains limited.
What does this case teach about chronic Babesia infection?
This case illustrates that persistent or relapsing babesiosis can occur in immunocompromised patients despite multiple antimicrobial regimens. Although tafenoquine produced meaningful clinical improvement and correction of anemia, it did not completely eliminate Babesia microti infection in this patient.
The report also highlights that prolonged combination therapy and careful follow-up may be necessary in selected patients with recurrent babesiosis. Management should be individualized based on immune status, clinical response, laboratory findings, and tolerance of therapy.
In my experience, some patients initially believed to have treatment-resistant babesiosis have improved after longer treatment courses or retreatment. These observations suggest that apparent treatment failure does not always indicate antimicrobial resistance and may instead reflect persistent infection, host immune factors, inadequate duration of therapy, or the need for prolonged treatment in selected patients.
Frequently Asked Questions
Can Babesia become chronic?
Yes. Persistent or relapsing Babesia infection is uncommon in healthy individuals but can occur in immunocompromised patients, particularly those with hematologic malignancies, asplenia, or those receiving immunosuppressive medications.
Can Babesia come back after treatment?
Yes. Some immunocompromised patients experience recurrent parasitemia after completing therapy and may require prolonged or combination antimicrobial treatment.
Does tafenoquine cure Babesia?
Evidence remains limited. While several case reports have described successful treatment, this report demonstrated relapse after approximately six weeks of tafenoquine therapy, suggesting that tafenoquine alone may not eradicate infection in every patient.
Who is most at risk for relapsing babesiosis?
Patients with impaired immune function—including those with lymphoma, asplenia, or treatment with immunosuppressive medications—are at the greatest risk for persistent or recurrent babesiosis.
Clinical Takeaway
This case illustrates the challenges of treating persistent Babesia microti infection in an immunocompromised patient. Although off-label tafenoquine was associated with improvement in anemia and temporary clinical stabilization, relapse occurred after the drug was discontinued, indicating that it did not completely eradicate the infection.
For patients with impaired immunity, recurrent babesiosis may require prolonged combination antimicrobial therapy, close laboratory monitoring, and individualized treatment decisions. Additional clinical studies are needed to clarify the role of tafenoquine and determine the most effective treatment strategies for relapsing babesiosis.
Persistent or relapsing babesiosis should not automatically be considered antimicrobial resistance, particularly in immunocompromised patients, as some individuals improve with retreatment or longer courses of therapy.
Related Articles
Prolonged Babesia Infection in a Patient with Asplenia
Congenital Transmission of Babesia Diagnosed in a 5-Week-Old Twin
Babesia Symptoms: Signs, Symptoms, and Diagnosis
Babesia Treatment: Current Treatment Options
References
- Prasad PJ, Wormser GP. Failure of an Approximately Six Week Course of Tafenoquine to Completely Eradicate Babesia microti Infection in an Immunocompromised Patient. Pathogens. 2022;11(9).
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
Dr. Cameron, I was just wondering if you’ve ever had success with treating Babesia with Alinia (nitazoxanide)? Thank you so very much for your time.
I don’t have enough experience to guide you.
For Babesia infection, treatment protocol using Ciprofloxacin can clear the parasite. 250mg x 3 times/day for five days can be curative. Cipro is good for mycoplasma infection too.
I have not seen any published evidence that ciprofloxacin is effective for Babesia.
I was diagnosed with babeesia in July. Still feel awful. Was given 10 days of azithromyicin and Avitoquoine. Seeing a Lyme dr. But he keeps giving me supplements that don’t help.
I have patients who have done well if their Babesia was treated long or retreated.
There are plenty of studies. Read the text carefully and start using fluoroquinolones (Cipro) for Babesia treatment. Curative protocol and can clear the infection really fast, one week treatment and the infection is cured, no symptoms and huge improvement.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6166754/
Thanks for sharing. I had not seen the intro study. The investigators included fluoroquinolones that are not available. I hope the investigators proceed to work with humans or animals. I would be interested in how humans tolerate fluoroquinolones as some patients with with Lyme disease and Babesia report tendonitis and muscle pain.