A change in the preponderant etiologic agent of tinea capitis in the United States has been occurring during the last 20 to 30 years. Before the 1950s, the Microsporum sp, M audouinii and M canis, were the organisms most commonly isolated in patients with tinea capitis. In the 1950s, Trichophyton tonsurans was introduced into the southern and southwestern states1,2 from Puerto Rico and Mexico, where epidemics of tinea capitis from this organism previously had occurred. In the early 1960s, the problem of scalp infections caused by T tonsurans also was reported in urban areas in the Midwest and East.3 In the 1970s, as Prevost reports (p 1765), T tonsurans is now the preponderant organism causing tinea capitis in Charleston, SC, a change also reported in other locations.4,5
The emergence of T tonsurans as the preponderant cause of tinea capitis is important, for scalp infections caused by this