Drug-resistant ringworm cases triple as fungus spreads to 29 countries, CDC finds

Reported cases of a drug-resistant ringworm fungus tripled over a nearly four-year period, with the strain now identified in 29 countries, according to a new study. The first U.S. case was reported in 2023, and researchers say the fungus is likely being undercounted in parts of Africa, India and the Middle East where it is already known to be common.

The study, published in the medical journal Emerging Infectious Diseases, analyzed data from March 2022 through the end of 2025. The drug-resistant strain does not respond to terbinafine, the antifungal medication used to treat most ringworm cases, allowing infections to persist for months.

Ringworm is a common fungal infection that causes an itchy, scaly, circular rash on the skin. The fungi that cause ringworm can also lead to infections such as athlete’s foot, and spread through skin-to-skin contact and through contaminated items such as towels, clothing, bedding and hairbrushes.

Most documented cases have been detected in Europe, but researchers say that likely reflects stronger surveillance and laboratory testing rather than a higher rate of infection. Limited access to advanced testing and tracking tools may be preventing health officials in other regions from fully measuring its spread, according to the report.