Borrelia miyamotoi Meningoencephalitis: Case Report

Neurologic symptoms can occur even without immunosuppression.
Confusion and headaches were initially mistaken for a mini-stroke.
Borrelia miyamotoi should be considered when Lyme EIA is positive but Western blot is negative.

Borrelia miyamotoi meningoencephalitis can occur even in immunocompetent patients. A 73-year-old man was admitted to the hospital with a 16-day history of confusion and intermittent headaches. He was an avid gardener and reportedly had tick bites in the past but none that he noticed in the weeks prior to his symptoms.

Initially, he developed “right-sided facial droop and associated numbness, confusion, and word-finding difficulties,” the authors write in the article “Borrelia miyamotoi Meningoencephalitis in an Immunocompetent Patient.”

His symptoms, which had improved, were attributed to a mini-stroke.

Progressive neurologic symptoms despite no fever

However, “Over the next 2 weeks, he continued to feel numbness in his right face and developed worsening confusion, intermittent headaches, and excessive fatigue; he was afebrile throughout this time.”

Initial testing and treatment

The patient tested positive for Lyme disease by EIA but negative by Western blot.

He was “empirically treated with intravenous ceftriaxone for treatment of presumed Lyme meningoencephalitis, and his mental status rapidly improved,” the authors write.

READ MORE: What is Borrelia miyamotoi?

Borrelia miyamotoi meningoencephalitis confirmed

When repeat testing for Lyme disease was negative by Western blot, clinicians considered another tick-borne infection — Borrelia miyamotoi.

The man tested positive for B. miyamotoi and made a “nearly full neurological recovery with only residual intermittent right facial numbness” after anti-Borrelia antibiotic treatment.

This case demonstrates that Borrelia miyamotoi meningoencephalitis should be considered in patients presenting with neurologic symptoms, even when they are not immunocompromised.

Why this case matters clinically

This report highlights a diagnostic challenge that clinicians may encounter in endemic regions. Patients with neurologic symptoms may initially test positive on Lyme EIA screening yet fail to meet Western blot criteria for Lyme disease.

In these situations, clinicians may need to consider Borrelia miyamotoi, particularly when patients present with confusion, encephalopathy, headaches, or facial neurologic findings.

Authors’ conclusions

• “Our case therefore highlights the need to include B. miyamotoi disease in the differential diagnosis for any patient who presents with acute onset, progressive encephalopathy with culture-negative CSF in B. miyamotoi–endemic regions, not just those who are immunocompromised.”
• “Our case highlights the importance of considering B. miyamotoi in clinically suspicious cases of meningoencephalitis, including when B. burgdorferi EIA results are positive but the WB is negative.”

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