First US cases of treatment-resistant ringworm found in patients in New York City

The US Centers for Disease Control and Prevention is reporting the first known cases of an antifungal-resistant ringworm in the United States and urging providers to be on the lookout for such infections.

The details of the cases were reported to the CDC in February and shared in a report published Thursday. The patients - two unrelated women in New York City - first had symptoms in 2021 and 2022. One patient had no international travel history, suggesting that there is some community spread in the US.

Despite the name, ringworm is not caused by a worm; rather, it is caused by one of 40 species of fungus. In this case, the infections were caused by Trichophyton indotineae, a recently discovered fungus.

Cases were first concentrated in patients in South Asia, but they've now also been found in countries in Europe. These are the first known US cases.

Ringworm can take several forms but often causes what looks like a superficial skin rash that forms a ring around otherwise normal-looking skin. It is a highly uncomfortable and itchy rash.

In the case of the first patient, the 28-year-old woman seemed to develop the rash in the summer of 2021. She went to see a dermatologist in December and said she had not traveled internationally, nor had she any known exposures to someone with a similar rash.

The report says the woman had "large annular, scaly, pruritic plaques" over her neck, stomach, pubic region and buttocks. Doctors put her on an oral therapy that she started taking in January 2022.