A case of human neoehrlichiosis with myocarditis in Germany: Clinical presentation and molecular diagnosis of the pathogen

Although rare, neoehrlichiosis in humans caused by N. mikurensis has gained increasing attention as an emerging tick-borne zoonosis, especially in immunocompromised patients in Europe. Here we report on a case of human neoehrlichiosis in Germany, which occurred in a 66-year-old woman with a history of granulomatosis with polyangiitis (GPA), B-cell depletion therapy, and secondary antiphospholipid syndrome. While undergoing long-term treatment for GPA with the monoclonal anti-CD20 antibody rituximab, the patient was hospitalized because of a prolonged fever of unknown origin (FUO) and hyperinflammatory syndrome. Neoehrlichiosis was diagnosed directly through eubacterial 16S rRNA PCR screening of EDTA whole blood from the patient, followed by genetic sequence analysis of the amplicon. In addition to a systemic infection, the patient also suffered from complicating myocarditis. Her condition eventually improved after treatment with doxycycline and a follow-up PCR revealed that the neoehrlichia DNA was finally cleared from her blood. Our findings provide further evidence that human neoehrlichiosis is endemic in Germany and suggest that N. mikurensis can also cause myocarditis. Consequently, in potential areas of endemicity, N. mikurensis should be considered in immunocompromised individuals with FUO and signs of infection.