First case of a rare, sexually transmitted form of ringworm reported in the USA

For the first time, a sexually transmitted case of ringworm caused by a rare fungus has been reported in the United States.

The case report from doctors at NYU Langone Health in New York City, published Wednesday in JAMA Dermatology, comes at a time when doctors around the world are increasingly reporting problems treating fungal infections.

“We think a lot about antibacterial resistance, but now it’s very important for us to think about fungal resistance as well,” said Mahmoud Ghannoum, a professor of dermatology at Case Western Reserve University School of Medicine in Cleveland. He was not involved in the new report.

The new case involves a man in his 30s from New York City who said he had sex with several men during a trip to England, Greece and California. When he returned home, he developed a red, itchy rash on his legs, groin and buttocks.

Tests revealed that he had a sexually transmitted fungus called Trichophyton mentagrophytes type VII. This is the first time the fungus has been detected in the United States. Last year, doctors in France reported 13 such cases. Twelve of these patients were men who have sex with men.

The American’s infection responded well to standard antifungal medications, but it took four and a half months to fully heal.

He was given fluconazole for four weeks without improvement, then terbinafine for six weeks, and itraconazole for about eight more weeks. All are oral antifungals.

He had no other infections that could have made the problem worse.

Dr. Avrom Caplan, assistant professor of dermatology at NYU Grossman School of Medicine and author of the new report, said the case should raise awareness but not cause public alarm.

“There’s no evidence that this is widespread or that this is something that people really need to be concerned about,” he said. “But if people have itchy rashes in areas like the groin and it doesn’t get better, they should see a doctor.”

The rash may look like eczema

Although the infection was most likely transmitted through sexual contact, Caplan could not rule out the possibility that the man contracted the fungus in a sauna he visited two months before his symptoms began. The man said his sexual partners had shown no signs of ringworm.

Caplan said the rash may look more like an eczema outbreak than typical ringworm, which forms in circles. The infection is not life-threatening but can leave permanent scarring.

He had previously identified the first two cases of another ringworm infection in 2023. These infections, caused by Trichophyton indotineaeare not considered sexually transmitted diseases, but are drug-resistant and highly contagious.

Since then, Caplan’s team at NYU Langone Health has identified a total of 11 cases of Trichophyton indotineae Ringworm in men and women in New York City.

The new case report is “remarkable,” said Jeremy Gold, a medical epidemiologist at the Centers for Disease Control and Prevention, stressing that doctors should consider fungi, along with viruses and bacteria, as a possible cause of sexually transmitted diseases.

“It often happens that these patients receive several courses of antibacterial medication, but these do not relieve the fungal infection,” he said. “Doctors should keep this in mind so that patients receive the appropriate treatment.” He was not involved in the new case report.

Caplan also encouraged people to speak up and seek treatment. Trichophyton mentagrophytes type VII is treatable.

“If you have a rash or skin lesions that don’t get better and you think it might be ringworm,” he said, “go see your doctor.”

This article was originally published on NBCNews.com.