Potential role of coypus (Myocastor coypus) in the epidemiology of botulism in wetlands

Botulism in wild birds is a widespread disease. Decaying carcasses of wild birds are known to amplify and perpetuate the disease through the “carcass-maggot” cycle. The role that other vertebrates may play in this epidemiological system has been poorly addressed until now. Among these, the role of the coypu (Myocastor coypus), a widespread invasive alien species raises questions. The aim of our study was to investigate the possible carriage and shedding of Clostridium botulinum C/D (responsible for avian botulism outbreaks in France) in coypus living near a pond with recurrent avian botulism outbreaks. A total of 106 coypus were opportunistically swabbed. The gene encoding the botulinum neurotoxin C/D was detected using a PCR approach. Samples positive for C. botulinum C/D in coypus and in wild birds during previous outbreaks were compared using a MLVA method (Multilocus Variable-Number Tandem-Repeat Analysis). Seven rectal swabs were positive for C. botulinum type C/D indicating a prevalence of 8% [3–16%]. MLVA comparison showed that the same MLVA profile was detected in coypus as from liver samples collected from dead birds during previous outbreaks. This shows that coypus can be asymptomatic carriers (whether permanent or transient needs to be further determined) and active or passive shedders of C. botulinum C/D with a MLVA profile identical to that of the strains responsible for clinical signs in birds in the past. These findings suggest that coypus may play a role in the epidemiology of botulism as potential sources and spreaders of C. botulinum C/D in the waterfowl environment, thus opening up new avenues of research to explore.