Researchers in New York have found an emerging threat of ringworm fungus, Trichophyton indotineae, which is often resistant to standard therapy, according to a study published May 15 in JAMA Dermatology.
The fungus has been detected worldwide, but data is sparse for its spread in the U.S., the researchers said. In May 2023, public health officials reported the first two confirmed T. indotineae cases in the U.S., but antifungal susceptibility testing data uncovered more infections, spanning back to 2017.
From May 2022 to May 2023, 11 patients in New York City had confirmed T. indotineae infections, and nine reported previous travel to Bangladesh. All had widespread lesions, diagnostic delays and did not respond to antifungal monotherapies. Terbinafine, the preferred treatment, was ineffective for seven patients.
Patients treated with fluconazole and griseofulvin improved in two of four and two of five instances, respectively, and itraconazole was effective for five of seven treated patients. Since these cases happened before May 2023, dermatologists were often unaware of T. indotineae at the time of treatment, the researchers said.
The fungal infection has the opportunity to become more widespread, they concluded, because they detected hundreds of single nucleotide variations, "which could indicate several independent introductions of T. indotineae or variants of T. indotineae isolates within New York City."
CIDRAP said the findings represent a new, emerging public health threat.