Neoehrlichia mikurensis and Borrelia miyamotoi co-infection in an immunocompromised patient.

Background

Neoehrlichia mikurensis and Borrelia miyamotoi are emerging tick-borne pathogens that primarily cause disease in immunocompromised individuals. Human co-infection with both pathogens has not previously been reported. CASE PRESENTATION A 55-year-old man receiving rituximab for primary progressive multiple sclerosis developed persistent fever, fatigue, malaise, and neck pain following a tick bite on Bornholm, Denmark. Multiple erythema migrans resolved after phenoxymethylpenicillin treatment, but systemic symptoms persisted. Borrelia burgdorferi serology was negative. Owing to ongoing symptoms and B-cell depletion, blood was analysed by 16S rRNA sequencing and species-specific PCR. Both B. miyamotoi and N. mikurensis DNA were detected and confirmed by independent laboratories. Treatment with doxycycline resulted in rapid clinical improvement and complete recovery.

Conclusion

To our knowledge, this is the first reported human co-infection with B. miyamotoi and N. mikurensis. The case highlights the importance of molecular diagnostics for emerging tick-borne infections in patients receiving anti-CD20 therapy.