First human-to-human transmission of the dermatophilosis bacterium

Around forty cases had been identified in France as of June 1, 2026, including about thirty in Lyon (east-central France), according to Dr. Maxime Bonjour, a public health physician at the Croix-Rousse Hospital in Lyon and one of the lead authors of a study published in the June issue of the journal Emerging Infectious Diseases (EID). It all started with the report of the discovery of a "atypical bacteria", in some of his patients undergoing preventive HIV treatment, who presented with pustules and scabs on the genitals, beard or torso.

Tests revealed they were suffering from dermatophilosis, a disease usually contracted by animals, visible on their backs. And it is a disease that has very rarely developed in certain professions (farmers, veterinarians, horse riders) – only 12 scientific articles, sometimes mentioning several cases, have been written since 1974. "But human-to-human transmission had never been identified.", according to Mr. Bonjour, also a doctor at the Cegidd in Lyon (HIV, hepatitis and sexually transmitted infection screening center).

"We hypothesize that this bacterium is sexually transmitted."

Read moreThe flu continues to rise, the peak is probably imminent.

The first nine patients identified in Lyon, who were part of the EID study, reported no contact with animals. However, all had frequented gay saunas where they had sexual relations, as had other men also affected in Spain at the same time, who were being monitored by teams in Barcelona.

"We hypothesize that this bacterium is sexually transmitted. A sexually transmitted dermatological infection occurring through close skin-to-skin contact, which would be facilitated by a warm and humid environment."Dr. Bonjour further explains.

Read moreIn Colombia, a mosquito factory to fight dengue fever and misinformation

Read alsoHantavirus: what really differentiates it from Covid-19

The disease "It is very easily treated with antibiotics and local care."

Good news: the disease "It is very easily treated with antibiotics and local care.", adds the doctor, who advises going to a Cegidd center when symptoms appear.

This discovery is "a further manifestation of the One Health concept" , Mr. Bonjour further notes that animal, human, and environmental health are interconnected. The European Union's health agency, the ECDC, is due to publish its first report on this disease on June 18, 2026.