New ringworm fungi spread sexually and are increasingly difficult to kill

Dermatologists are sounding the alarm about two new species of fungus that can cause severe bouts of ringworm. In a new report on Wednesday, they describe the first known case in the U.S. of a ringworm fungus that can spread sexually, while another recent paper describes the emergence of a species that is resistant to the most common antifungal drugs used to treat these infections.

RingwormDespite the name, it has nothing to do with parasitic worms. Rather, it is a reference to the circular rashes that are often caused by certain fungal infections of the skin. These infections are also known as tinea and can have other nicknames depending on the part of the body where they occur, such as athlete’s foot and tinea cruris for infections near the armpits or groin.

There are about 40 different types of fungi that can cause ringworm. These infections are usually mild (though very itchy) and treatable with antifungal medications. In recent years, however, dermatologists in Asia, Europe, and most recently the United States have observed ringworm infections that are a little stranger and more stubborn than usual.

Avrom Caplan, a doctor at New York University who specializes in autoimmune skin diseases, and his colleagues recently came across one of these cases. Their patient, a man in his 30s, developed scaly, circular rashes directly on and around his genitals. Initial tests identified the man’s fungus as a type that typically causes athlete’s foot or fungal infections of the toenails, but genetic sequencing revealed that it was actually the newly emerging fungus Trichophyton mentagrophytes ITS genotype VII or TMVII.

TMVII has been identified in parts of Europe and may be spread primarily through sexual contact, which is rare for other causes of ringworm. One study examined 13 cases of TMVII in France. published In the last year, there was evidence of sexual transmission in almost all cases. In these cases, all of the cases involved men, with 12 of them reporting that they had had regular sexual intercourse with men. Other Research has traced the origin of TMVII to Southeast Asia, where its initial spread may have been facilitated by contact with infected sex workers.

The French paper was actually what prompted Caplan and his colleagues to start looking for TMVII in the first place. And indeed, it didn’t take long for them to find a case on their radar. This latest case, published In Wednesday’s JAMA Dermatology, what appears to be the first case of TMVII reported in the United States has been reported, and it shares some of the same characteristics as previous cases. The patient reported recently traveling to Europe and California and having sex with multiple male partners during his travels.

“The takeaway for clinicians is that TMVII has arrived in the U.S. and we should be aware of it,” Caplan told Gizmodo.

Amazingly, this is the second fungus Caplan has crossed with recently. Last May, he and other researchers, including local and CDC health officials, detailed the first known cases of Trichophyton indotineae in the USA Last May, Caplan and others wrote an essay about this and other cases recently uncovered in New York City.

T. indotineaewhich probably first appeared in India, is concerning for several reasons. First, it tends to cause more severe ringworm, with itchy, sometimes atypical rashes all over the body that could be confused with eczema. Second, topical over-the-counter antifungal creams usually don’t work. The fungus is also often resistant to the main drug, terbinafine, even when taken orally, and often to two other oral drugs, fluconazole and griseofulvin. There is one drug that seems to work reliably at the moment, itraconazole, but treatment can take eight weeks or more for the infection to clear up completely, and it can interact with other common medications. As if that wasn’t bad enough, the fungus also seems to be able to sexually transmitted.

“Given the significant impact on quality of life, the potential for spread to other people, the typical failure of first-line oral antifungals, and the long duration of treatment required with an oral antifungal, this is very concerning and different from the more common ringworm that people may have, which is often treated with over-the-counter topical antifungal creams,” Caplan said.

We currently know less about TMVII, but that disease also appears to be more difficult to treat than the common type of ringworm. Caplan’s patient did not respond to an initial four-week course of fluconazole, although his condition improved after six weeks of terbinafine. Eventually, the patient was switched to a course of itraconazole, which seemed to clear the infection for good, Caplan said (the patient is still being monitored for safety).

At least for now, these new fungi do not pose an urgent public health problem in the United States. Importantly, the team found no evidence that TMVII or T. indotineae have become endemic to the area. But we need more research to better understand these new and different fungal threats, Caplan said.

For example, it is currently not possible to tell exactly how resistant these fungi are to a particular drug based on laboratory results alone, as doctors sometimes do for other types of infections. This lack of information can then delay a patient’s course of treatment. The team also hopes that their work can encourage other dermatologists to learn about these fungi in the first place. Both TMVII and T. indotineae can be confused with other common causes of ringworm during conventional testing, which can further delay appropriate treatment and prolong the patient’s suffering.

Caplan and others are working with public health authorities and the American Academy of Dermatology to spread the news about these fungi and develop easily accessible resources for the effective diagnosis and treatment of these infections.

“There are a lot of really great people working on these problems. And while these infections are concerning, there is a concerted effort to get them under control,” Caplan said.