Epidemiological investigation of a tularaemia outbreak after a hare hunt in Bavaria, Germany, 2018

Abstract

In November 2018, a tularaemia outbreak occurred in Bavaria, Germany, among participants of a hare hunt and butchery employees handling the hares. We con-ducted an epidemiological outbreak investigation, including a retrospective cohort study among hunting participants, to identify likely transmission routes and activi-ties associated with infection. Twelve of 41 participants were antibody- positive for Francisella (F.) tularensis (attack rate: 29%). Cases reported influenza- like symptoms (n= 11), lymphadenopathy (n= 1) and conjunctivitis (n= 1). Infection only occurred in those hunting participants present while hares were processed, while risk of infec-tion was highest when directly involved (RR = 10.0; 95%CI: 2.6–392). F. tularensiswas isolated from 1/4 hares. Only two individuals reported using some of the rec-ommended personal protective equipment (PPE). Occurrence of mainly non-specific symptoms, likely due to early treatment, was not indicative of a specific transmis-sion route. Transmissions via direct (skin/mucosa) contact and by inhalation of con-taminated aerosols seem plausible. Promoting and increasing appropriate use of PPE among people processing hares is crucial to prevent future outbreaks.