Rare animal skin infection jumps to humans in Spain and France.

A rare skin infection usually found in animals has jumped to nearly two dozen people, sparking fears it can now spread between humans. Experts analyzing two separate CDC reports identified distinct clusters of this condition among men who have sex with men in Spain and France.

Dermatophilosis, also known as rain rot, is caused by a bacterium that typically affects livestock and wildlife. Human cases are uncommon and usually occur after contact with cattle, sheep, horses, or animals like raccoons and skunks.

Historically, the disease thrives in tropical or wet climates, and human-to-human transmission has never been documented before. However, these recent cases present a puzzle. None of the infected men reported touching livestock or traveling to tropical regions.

Instead, researchers found a pattern linking the infections to sexual venues and specific behaviors. In the Spanish cluster, patients visited doctors in December 2025 and March 2026, while others sought care for sexually transmitted infections between January and March 2026.

Four of the men traveled to other European cities for sexual encounters. They all visited sex venues the week before their symptoms appeared. Eight patients also reported visiting saunas. Two pairs were regular sexual partners, while others mentioned partners with similar symptoms who had not been tested.

Symptoms included an itchy, red rash featuring scabs, nodules, and pustules. These lesions typically appeared on the face, genitals, legs, abdomen, thighs, groins, and bearded areas. The condition often clears up on its own, but severe cases require a seven-day course of oral antibiotics.

All infected men received antibiotics and fully recovered. Lab tests confirmed the presence of the Dermatophilus bacterium in each case.

The researchers drew a clear conclusion based on the evidence. They stated that attendance at sexual venues likely played a role in spreading the infection.

Furthermore, the specific locations of the skin lesions suggest direct skin-to-skin contact during sexual activity is the main route of transmission. Genomic data supports the finding that this bacterium can now transmit among humans.

Researchers confirm that dermatophilosis may act as a sexually transmissible infection within specific networks. This conclusion follows a cluster of genetically similar cases found in sexual communities. Environmental transmission remains a possibility, yet the evidence points strongly toward human-to-human spread.

A recent CDC report details a French outbreak involving nine men who visited University Hospital in Lyon between December 2025 and February 2026. These patients sought treatment for suspected sexually transmitted infections. Doctors later identified their condition as dermatophilosis.

Every patient identified as a man who has sex with men. None reported contact with livestock, wildlife, or travel to tropical regions. Symptoms appeared on genitals, abdomens, legs, and around the mouth. These lesions included papules and pustules on the bearded area and scrotum.

Seven of the nine men recently visited a gay sauna in Lyon before symptoms emerged. One patient listed multiple partners across various Paris saunas. Another patient visited one of the same locations. All men recovered fully after antibiotic treatment.

Researchers noted that the infection's clinical presentation differed from classical symptoms. They suggested a distinct clinical phenotype exists for this group. The combination of close genomic relatedness and shared sexual exposures suggests interhuman transmission within sexual networks.

This finding highlights how government directives and regulations must adapt to emerging public health threats. Officials must consider how sexual networks influence disease spread beyond traditional vectors. Community health risks grow when infections cross conventional boundaries.