Babesia in a MS Patient  Go Here for Podcast


babesia microti in MS patient

Welcome to another Inside Lyme Podcast. I am your host Dr. Daniel Cameron. In this episode, I will be discussing the case of a 54-year-old male with a 12-year history of multiple sclerosis who was diagnosed with Babesia microti.

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.

Disease Modifying Therapy

Ocrelizumab (sold under the brand name Ocrevus™ in the US) was approved in 2017 for the treatment of multiple sclerosis (MS). It is a humanized anti-CD20 monoclonal antibody, which targets mature B-cells that contribute to demyelination and damage to nerve cells.

Ocrelizumab is a disease modifying therapy (DMT) approved to treat both primary progressive MS and relapse-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 been associated with rare infections in non-MS patients including severe or relapsing Babesia microti infections, the authors wrote.

MS patient fails treatment

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

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

He was hospitalized with malaise, fever, fatigue for one week and episodes of syncope. He failed treatment with 4 different disease modifying drugs ─ glatiramer acetate, natalizumab, dimethyl fumarate, and fingolimod.

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

6 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 with PCR test results for Babesia microti returning positive.

The man was treated with 500mg daily azithromycin and 750mg twice daily atovaquone. 

“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 cases of Babesia microti 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.²

“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 with Babesia?



Inside Lyme Podcast Series


  1. Haberli N, Coban H, Padam C, Montezuma-Rusca JM, Creed MA, Imitola J. Babesia microti infection in a patient with multiple sclerosis treated with ocrelizumab. Mult Scler Relat Disord. Feb 2021;48:102731. doi:10.1016/j.msard.2020.102731
  2. Ezequiel M, Teixeira AT, Brito MJ, Luis C. Pseudotumor cerebri as the presentation of Lyme disease in a non-endemic area. BMJ Case Rep. 2018;2018.



This case brings up a very important point: MS can be caused or exacerbated by tick-borne infections. Immune-suppressing drugs are contraindicated for people with TBI’s. The only caveat to that is if they are used in conjunction with antibiotics.

I can’t help but wonder how many other patients are out there with this exact same scenario.

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