"Ringworm" - Tinea faciei
As most of you know, ringworm isn’t really a “worm”, or even an animal parasite. The condition is caused by one of over forty species of fungi (called dermatophytes) that live on the skin surface, and feed on keratin. The spores thrive on warm, wet surfaces, but can entrench themselves almost anywhere on the body. The name of the condition is determined by the location of infection - tinea capitis is on the scalp, tinea pedis is on the foot (athlete’s foot), tinea cruris is in the groin (jock itch/”crotch rot”), etc.
As the fungi are extremely easily spread by person-to-person contact, kids and people in institutional settings tend to contract the condition much more often than independent adults.
The original treatments for ringworm included mercury (oral and topical), sulfur, and iodine. Treatment of the scalp (tinea capitis) was considered more difficult than on the body, and frequently, x-ray treatment was used to kill the fungus.
The routine and accepted use of ionizing radiation to cure tinea capitis led to a long-standing incident among the Ashkenazi communities in Europe and the Middle East, called the "Ringworm affair". Starting in 1910, several hundred thousand people (mostly children) from close-knit Jewish communities were treated for the condition, in an attempt to eradicate it from a population known to routinely harbor or manifest the condition. However, the treatments were poorly-executed, the patients rarely had full information as to what was being done to them, and the excessive exposure to ionizing radiation is estimated to have killed at least 6,000 children shortly after receiving treatment (within 2 weeks). At least 100,000 other people have had long-term effects from the program, such as cancers, genetic anomalies in their children, and thyroid function problems.
The x-ray treatment program, which was for the most part well-intentioned but disastrously-executed, did not end until 1959, when the first effective and relatively safe antifungal compound, griseofulvin, was developed.
Illustrated Skin Diseases, An Atlas and Text-Book. William S. Gottheil, 1906.