Prevalence of Lawsonia intracellularis, Brachyspira hyodysenteriae, and Brachyspira pilosicoli infection in hunted wild boars (Sus scrofa) in Germany

Lawsonia intracellularis, Brachyspira hyodysenteriae, and Brachyspira pilosicoli are important pathogens in domestic pig production, responsible for porcine intestinal adenomatosis, swine dysentery, and porcine intestinal spirochetosis, respectively. They are widely distributed among pig-producing units around the world, and transmission is accomplished by relatively weak immunity, long shedding intervals, sequential shedding, and actual environmental survival. Little information is available on occurrence, prevalence, and quantity of these pathogens in free-ranging wild boars. The aim of the present study was to evaluate L. intracellularis, B. hyodysenteriae, and B. pilosicoli infections in wild boars in Germany. Tissue samples from ileocaecal mucosa of 165 wild boars from 18 hunting grounds situated in 14 of the 16 federal states of Germany were examined by conventional PCR and quantified by multiplex real-time PCR. None of the wild boars did show any gross pathological signs of enteritis. The overall prevalence for L. intracellularis, B. hyodysenteriae, and B. pilosicoli was 20.6%, 2.4%, and 12.1%, respectively. None of the three agents was detected in 68.5% of the wild boars and in 11.1% of the hunting grounds. Numbers of bacteria per sample were below the limit of quantification (100 cells/PCR reaction). This is the first study on L. intracellularis and Brachyspira spp. in free-ranging wild boars. The study revealed colonised animals without signs of disease. The meaning of these findings remains unclear, and we do not know whether and to what extent these three pathogens are exchanged between wild boars and domestic pigs. Further research is needed to get insight into the epidemiological impact of the results.