Babesia microti Infection in a Multiple Sclerosis Patient on Ocrevus

Welcome to another Inside Lyme Podcast. I am your host Dr. Daniel Cameron. In this episode, I discuss the case of a 54-year-old man with a 12-year history of multiple sclerosis who was diagnosed with Babesia microti while receiving ocrelizumab (Ocrevus).

Haberli and colleagues describe the case in the journal Multiple Sclerosis and Related Disorders.¹

Babesia microti, a tick-borne pathogen that infects red blood cells, can cause severe disease in immunocompromised individuals. This patient was immunocompromised due to multiple sclerosis (MS) and the immunosuppressive drug he was receiving, ocrelizumab. Learn more about Babesia infections and their role in tick-borne illness.

Disease-Modifying Therapy

Ocrelizumab (sold under the brand name Ocrevus™ in the United States) was approved in 2017 for the treatment of multiple sclerosis (MS). It is a humanized anti-CD20 monoclonal antibody that targets mature B cells involved in demyelination and nerve cell injury.

Ocrelizumab is a disease-modifying therapy (DMT) approved for both primary progressive MS and relapsing-remitting MS. Ocrevus™ can cost just over $65,000 per year if not covered by insurance.

The patient was prescribed Ocrevus™. “The use of ocrelizumab has been associated with increased risk of infections involving upper respiratory, gastrointestinal, and urinary tracts, in addition to herpes simplex reactivation,” wrote the authors.

“Data from one randomized clinical trial has shown a statistically significant increase in the incidence of malignancy among ocrelizumab users compared to placebo and interferon β1,” they added.

Rituximab, a medication with a similar mechanism of action, has also been associated with rare infections in non-MS patients, including severe or relapsing Babesia microti infection, the authors wrote.

MS Patient Fails Treatment

This is the first published case of Babesia microti infection in a patient treated with Ocrevus™.

The 54-year-old man had major depressive disorder, hypertension, and a 12-year history of relapsing-remitting multiple sclerosis.

He had previously been hospitalized with malaise, fever, fatigue for one week, and episodes of syncope. He had failed treatment with four disease-modifying drugs — glatiramer acetate, natalizumab, dimethyl fumarate, and fingolimod.

The man refused further therapy and was lost to follow-up.

Six Years Later, MS Symptoms Worsen

Six years later, the man’s MS symptoms worsened and he was prescribed Ocrevus™.

Four months later, he was hospitalized and treated for possible sepsis. He had unexplained thrombocytopenia (low blood platelet count).

Tests Positive for Babesia microti

As part of his sepsis work-up, the patient was tested for tick-borne infections, and PCR test results for Babesia microti returned positive.

The man was treated with azithromycin 500 mg daily and atovaquone 750 mg twice daily. “At week 8, his therapy was discontinued due to complete resolution of pancytopenia, negative B. microti PCR, and negative Giemsa-stained blood smear,” wrote the authors.

There have been other reported cases of Babesia microti infection in patients treated with Ocrevus™. “There were five babesiosis cases associated with ocrelizumab reported between June 2018 and August 2020 on the FAERS database,” the authors wrote.¹

“There were two females and two males with an age range of 45 to 51 years old, and one female 65 to 85 years old, all of whom had serious events without reported fatalities,” wrote the authors based on a review of the FDA Adverse Event Reporting System (FAERS) public dashboard.

The following questions are addressed in this podcast episode:

1. What is Babesia microti?
2. How do you diagnose Babesia?
3. Is testing accurate?
4. How severe is Babesia?
5. Are there asymptomatic cases of Babesia?
6. Why do immunosuppressive drugs pose a risk to Babesia patients?
7. What are the risk factors for symptomatic Babesia?
8. What is a disease-modifying agent?
9. What is Ocrevus™?
10. What was the treatment for Babesia?
11. What is the significance of 8 weeks of treatment for Babesia?

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Key Point

Babesia microti infection can occur in patients receiving immunosuppressive therapies such as ocrelizumab. Tick-borne infections should remain on the differential when immunocompromised patients present with unexplained fever, fatigue, cytopenias, or sepsis-like illness.

Clinical Insight

As disease-modifying therapies become more common in multiple sclerosis and other autoimmune disorders, clinicians should remain alert for opportunistic infections, including tick-borne pathogens such as Babesia microti.

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Thanks for listening to another Inside Lyme Podcast. You can read more about these cases in my show notes and on my website at DanielCameronMD.com. As always, your likes, comments, reviews, and shares help spread the word about Lyme disease. Until next time on Inside Lyme.

Please remember that the advice given is general and not intended as specific advice for any particular patient. If you require specific advice, please seek care from an experienced professional.

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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