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

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.Peer Reviewe

Outbreak of Tularemia in a Group of Hunters in Germany in 2018—Kinetics of Antibody and Cytokine Responses

In November 2018, an outbreak of tularemia occurred among hare hunters in Bavaria, Germany. At least one infected hare was confirmed as the source of infection. A number of hunting dogs showed elevated antibody titers to Francisella tularensis, but the absence of titer increases in subsequent samples did not point to acute infections in dogs. Altogether, 12 persons associated with this hare hunt could be diagnosed with acute tularemia by detection of specific antibodies. In nine patients, the antibody and cytokine responses could be monitored over time. Eight out of these nine patients had developed detectable antibodies three weeks after exposure; in one individual the antibody response was delayed. All patients showed an increase in various cytokines and chemokines with a peak for most mediators in the first week after exposure. Cytokine levels showed individual variations, with high and low responders. The kinetics of seroconversion has implications on serological diagnoses of tularemia