Two peer-reviewed papers in the June issue of Emerging Infectious Diseases, the CDC's open-access epidemiology journal, document suspected sexual transmission of Dermatophilus congolensis, a skin bacterium previously known only from cattle and sheep, among men who have sex with men in Barcelona and in Lyon and Paris, between December 2025 and March 20261. Dermatophilosis causes crusted skin lesions in cattle and sheep, and these papers document the first suspected spread of the organism from one person to another.
The Barcelona series of nine cases found lesions at contact sites, two confirmed partner pairs, and whole-genome sequencing placing the isolates 0 to 4 single-nucleotide differences apart. That genetic tightness, not the case count, is the signal: a cluster this close points to one human-transmitting lineage rather than repeated, separate spillover from animals. The authors judge skin-to-skin contact during sex the likely main route. This is the peer-reviewed evidence behind the 50-case sauna observation the ECDC, the European Centre for Disease Prevention and Control, flagged earlier.
The finding is best read as a surveillance observation in a community where sexual-health screening is unusually dense, which raises the odds of catching a novel organism early, rather than a sign of unusual or alarming spread. Frequent screening detects a rare bacterium here before it would surface in less-tested groups, which says more about where testing is thorough than about where the organism is concentrated. The ECDC's rapid risk assessment, its formal scientific judgement on the threat level, is due 23 June.
