A survey of 631 preschool children in Panama and the Canal Zone revealed an over-all prevalence rate of 6.3 per cent hypersensitivity to histoplasmin and 3.5 per cent hypersensitivity to PPD skin tests.
Among forty children with positive histoplasmin skin tests there was evidence of clinical disease in only three. Roentgenographs of the chest revealed infiltration or adenopathy in six, and calcifications in four. Complement-fixation tests were positive in nineteen.
Present address: The Children's Memorial Hospital, Chicago, Illinois.
Present address: Department of Bacteriology, Walter Reed Army Institute of Research, Washington 12, D. C.