Is It Lyme Disease—or Borrelia miyamotoi in California?
Relapsing fever—but not Lyme?
Are tests missing the diagnosis?
Borrelia miyamotoi may be overlooked.
What if it’s not Lyme disease? In patients with relapsing fevers and negative Lyme tests, another tick-borne infection may be missed.
“Although B. miyamotoi has been identified in ticks in California for more than 20 years, locally acquired human cases in the western United States have not been described in the literature,” according to Rubio et al.
In this case report, the authors describe an immunocompromised man living in California diagnosed with Borrelia miyamotoi infection.
The man had multiple sclerosis and was receiving an anti–B lymphocyte CD20 monoclonal antibody (ocrelizumab). He presented with intermittent, relapsing fevers over two months.
“The febrile episodes typically lasted 1 day, occurred every 10–14 days, and were associated with night sweats, mild vision changes, and nausea,” the authors write.
A key pattern is relapsing fever. Symptoms occurred in cycles rather than a continuous illness.
“Laboratory confirmation of B. miyamotoi infection can be challenging because the spirochetes share many proteins with B. burgdorferi and B. hermsii, resulting in cross-reacting antibodies.”
The patient tested positive for Epstein-Barr viral capsid and nuclear antigen IgG, with thrombocytopenia and elevated C-reactive protein. However, tests for Borrelia burgdorferi, brucellosis, and leptospirosis were negative.
A key pattern is diagnostic mismatch. Symptoms suggest infection, but standard Lyme testing is negative.
Testing Confirms Borrelia miyamotoi Infection
Given the patient’s immunocompromised status and relapsing fevers, clinicians pursued further evaluation using plasma microbial cell-free DNA sequencing.
“Borrelia miyamotoi infection was diagnosed through molecular testing with unbiased plasma mcfDNA sequencing, an increasingly used tool for evaluating patients with fever of unknown etiology,” the authors write.
Few laboratories currently offer testing for B. miyamotoi.
A key pattern is advanced testing. Diagnosis required methods beyond standard serologic testing.
The patient was treated with a 4-week course of doxycycline, resulting in complete resolution of symptoms.
A key pattern is reversibility. Symptoms resolved with appropriate treatment.
Tick Investigation and Exposure
The state health department collected ticks from areas surrounding the patient’s home in Marin County, California. Nineteen I. pacificus ticks were identified, but none tested positive for B. miyamotoi. One tick was positive for Borrelia burgdorferi.
The authors note that the patient had traveled to Ohio two months prior to symptom onset, raising the possibility of exposure outside California.
“Our study suggests that B. miyamotoi is an emerging human pathogen in California.”
Clinical Implications
A key pattern is overlap. Borrelia miyamotoi infection can resemble Lyme disease but may not be detected with standard testing.
If patients present with relapsing fever and negative Lyme testing, consider alternative tick-borne infections.
Authors Conclude:
- “For patients with high or relapsing fever during Ixodes tick activity, clinicians should consider B. miyamotoi infection alongside other Borrelia species.”
- “Cross-reacting antibodies can complicate diagnosis.”
- Immunocompromised status may increase risk of persistent infection.
Authors Suggest:
- Maintain suspicion in relapsing fever without clear etiology and consider molecular testing.
Related Articles:
What does Borrelia miyamotoi cause?
References:
- Rubio LA, Kjemtrup AM, Marx GE, et al. Borrelia miyamotoi infection in an immunocompromised patient, California, USA. Emerg Infect Dis. 2023.
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
