Highly Contagious and Drug-Resistant Ringworm Reported in US for First Time

New York City is home to the country’s first-ever reported cases of ringworm infections that are highly contagious and resistant to common anti-fungal treatments, according to the Centers for Disease Control and Prevention.

Two cases were reported to state health officials by the dermatologist in February, and those cases are briefly documented in a case study released Thursday in the CDC’s Morbidity and Mortality Weekly Report.

“On February 28, 2023, a New York City dermatologist notified public health officials of two patients who had severe tinea that did not improve with oral terbinafine treatment, raising concern for potential T. indotineae infection; these patients shared no epidemiologic links,” according to CDC.

The first case dates back to the summer of 2021, and it involved a pregnant woman in her twenties who had never left the country, was in perfect health, and had never been in contact with anyone else who had a similar rash. This incident may indicate that the fungus is spreading subtly throughout the area.

Her infection from 2021 wasn’t treated until early 2022.

Patient A, a woman aged 28 years, developed a widespread pruritic eruption during summer 2021. She had a first dermatologic evaluation in December 2021, at which time she was in her third trimester of pregnancy. She had no other underlying medical conditions, no known exposures to a person with similar rash, and no recent international travel history. Dermatologists noted large, annular, scaly, pruritic plaques over the neck, abdomen, pubic region, and buttocks. She received a diagnosis of tinea and began oral terbinafine therapy in January 2022 after the birth of her baby. Because her eruptions did not improve after 2 weeks of therapy, terbinafine was discontinued, and she began itraconazole treatment. The rash resolved completely after completing a 4-week course of itraconazole; however, she is being monitored for potential recurrence of infection and the need for resumption of itraconazole.

A woman in her forties who visited Bangladesh and came back with a severe case of ringworm was the second person to be diagnosed with this particular condition.

Patient B, a woman aged 47 years with no major medical conditions, developed a widespread, pruritic eruption in summer 2022 while in Bangladesh. There, she received treatment with topical antifungal and steroid combination creams and noted that several family members were experiencing similar eruptions. After returning to the United States, she visited an emergency department three times during autumn 2022. She was prescribed hydrocortisone 2.5% ointment and diphenhydramine (visit 1), clotrimazole cream (visit 2), and terbinafine cream (visit 3) with no improvement. In December 2022, she was evaluated by dermatologists who noted widespread, discrete, scaly, annular, pruritic plaques affecting the thighs and buttocks (Figure). She received a 4-week course of oral terbinafine, but her symptoms did not improve. She then received a 4-week course of griseofulvin therapy, resulting in approximately 80% improvement. Itraconazole therapy is being considered pending further evaluation given the recent confirmation of suspected T. indotineae infection. Her son and husband, who live in the same house and report similar eruptions, are currently undergoing evaluation.

U.S. Centers for Disease Control and Prevention concludes:

The cases in these two patients highlight several important points. Patient A had no recent international travel history, suggesting potential local U.S. transmission of T. indotineae.

Health care providers should consider T. indotineae infection in patients with widespread tinea, particularly when eruptions do not improve with first-line topical antifungal agents or oral terbinafine. Culture-based identification techniques used by most clinical laboratories typically misidentify T. indotineae as T. mentographytes or T. interdigitale; correct identification requires genomic sequencing.

Health care providers who suspect T. indotineae infection should contact their state or local public health department for assistance with testing, which is available at certain public health laboratories and specialized academic and commercial laboratories. Successful treatment using oral itraconazole, a triazole antifungal, has been documented.

However, providers should be aware of challenges with itraconazole absorption, which can lead to variable serum drug concentrations; itraconazole’s interactions with other drugs; the need for up to 12 weeks of therapy (3); and the documented emergence of triazole resistance (4,5). Antimicrobial stewardship efforts are essential to minimize the misuse and overuse of prescribed and over-the-counter antifungal drugs and corticosteroids.

In addition, health care providers can educate patients about strategies to prevent the spread of the dermatophytes that cause tinea.

Finally, public health surveillance efforts and increased testing could help detect and monitor the spread of T. indotineae.