Abstract
The coypu (Myocastor coypus Molina) is an aquatic rodent that has become a widespread pest in the south-east of England. Since the natural habitat of this animal is aquatic, the possibility of infection with leptospires was investigated. Twenty-nine coypu were trapped and examined by serological, histological and cultural methods. Of these, there was serological evidence of infection in seven coypus and Leptospira interrogans var. Wolffii was isolated from a further animal. This appears to be the first report of the isolation of leptospira from a coypu in Great Britain.