During the year 1932 certain changes made in the scarlet fever quarantine requirements by the Illinois State Department of Health and the Chicago Board of Health offered an unusual opportunity for a study of the secondary case of scarlet fever and the duration of scarlet fever infectivity. Four series were investigated, in which 4,315 patients were discharged from the Municipal Contagious Disease Hospital under different regulations.
In the first group the quarantine period was four weeks for uncomplicated cases. Patients with abnormal discharges, however, were held in the hospital until they were clinically well, with the stipulation that the maximum period should not exceed ninety days. Under this arrangement, between Jan. 1 and July 6, 1932, there were discharged 1,454 patients, 235 of whom were adults. Among the 1,454 patients, sixty-two, or 4.2 per cent, were responsible for secondary or so-called return cases of scarlet fever. To these sixty-two patients,