The first case of a 'highly contagious' ringworm infection spread through sex has arrived in the US, researchers say

• A sexually transmitted fungal infection, TMVII, has been reported in the US for the first time.
• The infection, which resembles eczema, often affects men who have sex with other men.

Researchers in New York are warning that a sexually transmitted fungal infection that can take months to resolve has been reported for the first time in the US.

In a report published on Wednesday in the peer-reviewed journal JAMA Dermatology, medical experts highlighted the case of a man in his 30s who had just arrived in New York City.

He suffered a fungal infection on his penis, buttocks, and limbs after arriving from a trip to England, Greece, and California, wrote the researchers from New York University and the New York State Department of Health in Albany.

These rashes were found to have been caused by a ringworm called the Trichophyton mentagrophytes type VII, or TMVII, according to the study.

One of their concerns is that the infection can be confused as lesions from eczema and can go untreated.

The infection appears to often affect men who have sex with other men, researchers said, citing 13 cases reported in France last year.

The male patient in the newly published study reported engaging in sex with multiple male partners on his travels, they added.

They warned that even if treated, infections like these can take months to clear up and are highly contagious.

"Healthcare providers should watch out for new and highly contagious forms of ringworm or jock itch, which are emerging as a potential public health threat," read an NYU press release about the report.

John Zampella, a senior author of the paper and an associate professor of dermatology at NYU's Grossman School of Medicine, encouraged doctors to check on rashes they see around their patients' groin and buttocks.

The researchers said the infection can often be difficult to treat but seems to respond well to terbinafine, an antifungal medicine that can be administered orally or as a gel on the skin.

Meanwhile, another fungus that causes contagious rashes like those from TMVII has been found to resist the medicine, the researchers said.

They highlighted T. indotineae, which they said they tested in 11 patients from May 2022 to 2023. Patients affected by the fungus didn't have their rashes improve even after 42 days of treatment with terbinafine, they added.

T. indotineae has largely affected India, but more cases have been reported globally in recent years.

Researchers wrote that itraconazole, an antifungal treatment, appears to work well. However, if used for prolonged periods, it can often interfere with other medicines or cause side effects such as diarrhea.