Overview
- In mid-June 2026 investigators reported about forty confirmed cases of dermatophilosis, with roughly thirty cases linked to Lyon and others reported in Barcelona and several French cities.
- Laboratory sequencing showed nearly identical strains in France and Spain, and teams say shared sexual exposures support probable human-to-human transmission rather than animal contact.
- Most patients have been men who have sex with men and many recalled recent sexual encounters in gay saunas, places researchers say may amplify spread because heat and humidity help the bacterium's waterborne zoospores reach skin.
- Clinical cases have been mild so far, presenting as pustules, vesicles or crusts on the genitals, trunk or beard, and patients have improved quickly with oral antibiotics and topical care.
- Health teams in Lyon and Barcelona are expanding epidemiologic tracing and surveillance to define the outbreak and advise clinicians to consider this diagnosis when skin lesions resemble common sexually transmitted infections.