The European brown hare (Lepus europaeus) is a quite adaptable species, but populations have been decreasing for several decades in different countries, including Germany. To investigate infectious diseases as possible influences on observed population decline in the German federal state Schleswig-Holstein, 118 deceased free-ranging European brown hares were collected between 2017 and 2020 and underwent detailed postmortem examination with extended sampling. Infectious diseases were a major cause of death (34.7%). The number of juveniles found exceeded the adult ones. The main pathomorphological findings were hepatitis (32.8%), pneumonia (22.2%), nephritis (19.1%), liver necrosis (12.9%), and enteritis (40.7%). An unusual main finding was steatitis (20.9%) of unknown origin. Animals were mainly emaciated and showed high infection rates with Eimeria spp. (91.3%) and Trichostrongylus spp. (36.2%). European Brown Hare Syndrome Virus reached an epidemic status with few fatal infections (4.2%) and high seroprevalence (64.9%), whereas the prevalence of Rabbit Haemorrhagic Disease Virus 2 was very low (0.8%) in hares in Schleswig-Holstein. Pathogens such as Yersinia pseudotuberculosis (5.9%), Pasteurella multocida (0.8%), and Staphylococcus aureus (3.4%) only caused sporadic deaths. This study illustrates the wide distribution of various infectious pathogens with high mortality and even zoonotic potential. Infectious diseases need to be considered as an important influence on population dynamics in Schleswig-Holstein.
The lagomorph‐infecting Treponema paraluisleporidarum is a close relative of the human syphilis‐bacterium Treponema pallidum. There is a paucity of information on the epidemiology of hare syphilis and its relationship to the rabbit‐ and human‐infecting treponemes that cause syphilis. In our study, we tested 734 serum samples from European brown hares (Lepus europaeus) collected between 2007 and 2019 in the federal state of Lower Saxony, Germany, for the presence of antibodies against T. paraluisleporidarum. Since T. paraluisleporidarum cross‐reacts with T. pallidum antigen, we used a commercially available T. pallidum‐particle agglutination (TP‐PA) assay to test for the presence of antibodies. A high seropositivity (n = 405/734) was detected. An additional 233 serum samples were retested using a fluorescent treponemal antibody absorption test to confirm the results of the TP‐PA assay. Our results show that infection is widespread in Lower Saxony and suggest a horizontal (sexual) transmission mode since adult hares show significantly higher seropositivity than subadults (odds ratio: 0.03 [95% CI 0.02–0.05], p < .0001). No difference was detected based on gender (odds ratio: 0.79 [95% Cl 0.58–1.07], p = .1283). Further studies are warranted to genetically characterize the T. paraluisleporidarum strains that infect wild hares.
Treponema paraluisleporidarum infects lagomorphs and is a close relative of the human syphilis-bacterium Treponema pallidum. There is paucity of information on the epidemiology of hare syphilis and its relationship to rabbit- and human-infecting Treponema. We have found a high seropositivity (405/734) for Treponema paraluisleporidarum-infection in hares of Lower Saxony, Germany.
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