<i>Notes from the Field:</i> First Reported U.S. Cases of Tinea Caused by <i>Trichophyton indotineae —</i> New York City, December 2021–March 2023

Abstract

Tinea is a common, highly contagious, superficial infection of the skin, hair, or nails caused by dermatophyte molds.*During the past decade, an epidemic of severe, antifungalresistant tinea has emerged in South Asia because of the rapid spread of Trichophyton indotineae, † a novel dermatophyte species; the epidemic has likely been driven by misuse and overuse of topical antifungals and corticosteroids § (1,2).T. indotineae infections are highly transmissible and characterized by widespread, inflamed, pruritic plaques on the body (tinea corporis), the crural fold, pubic region, and adjacent thigh (tinea cruris), or the face (tinea faciei) (1).T. indotineae isolates are frequently resistant to terbinafine, a mainstay of tinea treatment (1,3).T. indotineae infections have been reported throughout Asia and in Europe and Canada but have not previously been described in the United States (3).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.Skin culture isolates from each patient were previously identified by a clinical laboratory as Trichophyton mentagrophytes and were subsequently forwarded to the Wadsworth Center, New York State Department of Health, * Commonly known as "ringworm," tinea is most often caused by dermatophyte molds belonging to the genus Trichophyton.The infection spreads easily by skin-to-skin contact with infected animals or persons, secondary spread from other affected body sites, and fomites.Most skin infections are localized and resolve with topical antifungal treatment, and oral antifungal therapy is generally reserved for cases that do not improve with topical treatment or those with extensive disease or infection of the hair follicles.https://www.cdc.gov/fungal/diseases/ringworm/definition.html† The etiologic agent causing the epidemic of drug-resistant tinea in South Asia was initially identified as T. mentagrophytes ITS genotype VIII.However, based on recent genomic studies, scientists determined that these frequently terbinafine-resistant Trichophyton strains were sufficiently different from T. mentagrophytes to be considered a new species, T. indotineae.§ The emergence and spread of T. indotineae in South Asian countries have been linked to the inappropriate use of widely available topical combination creams containing antifungals, antibiotics, and high-potency corticosteroids.https:// www.cdc.gov/fungal/diseases/ringworm/dermatophyte-resistance.