The role of the coypu (Myocastor coypus), an invasive aquatic rodent species, in the epidemiological cycle of leptospirosis: a study in two wetlands in the East of France

Abstract

Leptospirosis is caused by pathogenic species of the Leptospira genus. Animals can have two roles in the epidemiological cycle: they can be an accidental host and suffer of the disease or a reservoir host which does not express any clinical sign and shed bacteria in their urine. Some of the most known reservoirs for leptospirosis are certain rodent species, but the situation is less clear for aquatic rodents, especially for coypu (Myocastor coypus). It has been shown that this species can have kidney carriage for leptospirosis, but the relationship between carriage and individuals or population health has not been investigated yet. We trapped 133 coypus in two wetlands in the East of France during 3 years. For each animal, a complete necropsy, leptospirosis serology, and a specific real-time quantitative PCR (qPCR) for pathogenic leptospires were performed; in addition, for some animals, a specific kidney culture for leptospires and histology on kidney were performed. In spite of a high seroprevalence (respectively 76 % and 64 %) and of a significant prevalence of kidney carriage in both areas (respectively 12.1 % and 8.0 % of positive qPCR on kidney), the trapped animals seemed in good health, and the population did not seem to be affected by the circulation of the bacteria. These findings are concurring arguments to consider coypu as a real reservoir for leptospirosis.