Ringworm of the scalp is caused by several species of fungi, the most common being the Microsporon audouini and Microsporon lanosum.The M. audouini is capable of causing widespread out- breaks.Other species of fungi causing sporadic cases of tinea capitis are the M. fulvum, Achorion schoenleinii (favus), and other tricho- phyton organisms.This paper will deal chiefly with the M. audouin&i infections.In recent years, epidemic outbreaks of ringworm of the scalp in large city areas, especially in the eastern United States, have been repeatedly reported in dermatological and general medical literature.Little has been written in public health journals and the author believes that there should be greater recognition by public health officials of the seriousness of this communicable disease. INCIDENCEAs early as 1899, Dr. C. J. White reported on ringworm as it existed in Boston.Lewis and Hopper in 1939 reported a series of 278 cases observed and treated at the New York Post Graduate Medical School and Hospital during the period between 1935 and 1938.All of these cases were proved by culture-M.audouini accounting for 39.3 percent and M. lanosum, 39.6 percent, together causing 229, or 78.9 percent, of the cases.Benedeck and Felscher of Chicago reported 140 cases for the period between May 1, 1940, through August 31, 1942.Of this number, 81.5 percent were due to M. audouini and 12.2 percent to M. lanosum.Livingood and Pillsbury of Philadelphia in 1941 reported a series of 130 cases, 125, or 96.2 percent of which were due to M. audouini.Lewis, Hopper, and Reiss reported 312 cases at the New York Hospital fromJuly 1, 1943, to June 30, 1945.M. audouini was present in 275 of these cases.Miller, Lowenfish, and Beattie at the Vanderbilt Clinic in New York City Lewis, Silvers, Cipollaro, Muskatblit, and Mitchell reported in 1944 that of the 432 cases occurring in Astoria Queens, New York, during an epidemic in 1943, 411 were due to the M. audouini.Statistics at the New York Skin and Cancer Hospital show that during the period from 1935 to 1942, 292 of the 616 cases of tinea capitis reported were due to M. audouini.In 1943, of 572 cases of tinea capitis treated there, 496 were due to M. audouini.Lynch reported that the estimates of the incidence of the infection in Chicago varied from 5,000 to 65,000 cases.In St. Paul the disease increased to a point where the Minnesota Dermatological Society was impelled in 1944 to call to the attention of public health authorities, the danger of an impending epidemic.At the time of his report he estimated that there were between 150 and 500 cases of the disease in St. Paul.Carrick has reported on an interesting and valuable survey in 1946 among Detroit elementary school children.Of 3,565 children selected at random in a city-wide survey, 96, or 2.7 percent, showed evidence of infection under filtered ultraviolet light.On the basis of total enrollment of children susceptible to tinea, it was estimated that there were about 6,000 cases of ringworm of the scalp among the 220,291 children in Detroit public schools.In this survey, the principal of each of the 21 schools of the 7 large districts in Detroit selected alphabetically every fifth child under 13 years of age for examination under Wood's light.Ringworm of the scalp has an epidemic character and is prevalent and widespread in schools and institutions.Many children with this infection are kept out of school for an average of 6 months or more.Some cases are cured in 6 months but others remain under treatment and out of school for several years.Epidemics of ringworm of the scalp resulting from M. audouini have occurred in Europe, especially in France and England, for years.In the United States, sporadic epidemics have been observed and reported but it was not until about 1942 that widespread epidemics were reported in the large eastern cities.One of the first outbreaks was reported in Astoria, New York City, by Lewis, Silvers, Cipollaro, Muskatblit, and Mitchell.They felt that the outbreaks resulted from the fact that during the war there was decreased maternal care and supervision, and that infected children were moved from place to place because of changes of residence of their parents who were in the armed forces or were war workers.During this period most of the children's institutions were crowded and had ineffi- cient supervision.It is also pointed out that the disease was inadequately dealt with by health authorities, partly because of ignorance concerning its epidemiology, lack of experience with the epidemic character of the disease, procrastination be- cause the disease causes no mortality, and the difficulty of carrying out a diagnostic and treatment program of city-wide proportions. CHARACTERISTICS OF THE DISEASERingworm of the scalp is characterized by localized, round scaly patches of alopecia with short broken-off hair.The fungus invades the hair and hair follicle, multiplies, and progresses down the wall of the follile.Soon large numbers of mycelia form around the hair between it and the walls of the follicle.The mycelia and spores increase and proceed downward in the hair to the point where the hair bulb begins.The hair papiUla which is responsible for the reproduction of new hair is never involved in this process.However, the hair will break off at the weakest point, which is the position of greatest parasitic invasion, just a few millimeters above the surface of the ' Imported.