Evidence for multiple cases of recurrent <i>Legionella</i> infection: a Danish national surveillance study.

Abstract

While case reports have documented recurrence of Legionnaires' disease, the frequency of recurrent infections has not been systematically examined at a national level over multiple decades. Between 2000 and 2020 in Denmark, 21 individuals had repeat laboratory-identified <i>Legionella</i> infection, totalling 48 episodes of hospitalisation. The majority of these individuals had underlying comorbidities. In at least 3 of the 21 cases, a different <i>Legionella</i> serogroup was detected during the second episode of infection, which could indicate reinfection from a new source. These results emphasise that <i>Legionella</i> can, and does, reinfect high-risk individuals causing multiple hospitalisations.