An Outbreak of Microsporum canis infection at a military base associated with stray cat exposure and person-to-person transmission

Tinea corporis caused by Microsporum canis is usually associated with exposure to animals, but outbreaks with anthropophilic transmission were described. A large outbreak in a military base was investigated. We investigated the outbreak’s source and risk factors for infection in order to contain and eliminate it. All staff-members at the base were interviewed and examined. A case-control analysis of symptomatic patients was used to elucidate risk factors. Stray cats were captured and sampled. M. canis isolated from skin and fur specimens of patients and cats were genotyped by microsatellite sequencing. Fifty-three of 502 staff-members were symptomatic. Logistic regression showed risk associated with female gender, cat contact at base and performance of guarding duty. Multiple stray cats were found at the base. M. canis isolates from 4 cats and 4 patients had an identical genotype, while 2 patients had different genotypes. We describe the largest M. canis outbreak reported until now. Epidemiological and phylogenetic tools were used to investigate the source of the outbreak. Multiple exposures to stray cats caused infection of mainly young female soldiers performing guarding duty. Other persons were infected by person-to-person transmission. These findings aided in the termination of the outbreak.