Epidemiology of Tularemia among Humans and Animals, Baden-Wuerttemberg, Germany, 2012–2022

Abstract

Tularemia, a zoonosis caused by Francisella tularensis, is endemic in Baden-Wuerttemberg, Germany. To determine tularemia epidemiology in this region, we characterized the genetic diversity of F. tularensis in human and animal isolates during 2012–2022 by using whole-genome sequencing, combined with human and veterinary surveillance data analysis. Human case numbers varied; most cases occurred in 2021 (n = 34). Arthropod bites were reported most in cases with information on animal exposure (45%, n = 43). Poisson regression confirmed a significant increase in human cases during the study period (p<0.001). No seasonal pattern was identified, but case numbers were lowest in winter. Human surveillance data often lacked exposure details. Positivity rates in animals were 5%–34%, increasing since 2017. Human isolates often clustered with hare-derived strains, although transmission routes often remain unclear. These findings emphasize the importance of combining genome sequencing with detailed epidemiologic tracing to identify infection sources and improve surveillance data.