Isolation of Treponema hyodysenteriae from wild rodents

Rodents from swine-producing farms were examined for the presence of Treponema hyodysenteriae. Wild mice (n = 257) and rats (n = 41) were trapped on eight farms. Ceca were removed aseptically, and the contents and mucosal scrapings were cultured on selective medium (blood agar containing 400 micrograms of spectinomycin per ml). T. hyodysenteriae was detected in the cecal scrapings of four mice from three different farms where swine dysentery had occurred. Gross lesions were detected in the ceca in two of the four mice. In addition, Treponema innocens was detected in the cecal scrapings of 12 mice and 13 rats. Three of the four T. hyodysenteriae isolates were pathogenic when inoculated intragastrically into swine. The results of this investigation suggest that wild rodents may be carriers of T. hyodysenteriae.