Quantitative Aspects of the Intradermal Test with Cercarial Antigen in Schistosomiasis

Abstract

The intra-dermal test was performed in 250 patients with stools positive for Schistosoma mansoni eggs. The patients were taken from 3 age groups: 10 to 15 years (100 individuals); 16 to 19 years (50 individuals) and 20 years and more (100 individuals). Injections were applied to the flexor surface of the forearms on the same occasion for each patient and 5 different concentrations of the antigen (10-7 to 10-3) and a control were used. Areas of the wheals were determined with a planimeter. Analysis of the results gave evidence of the following: the relation of the mean response to log concentration of the antigen was linear within the range of the concentrations 10-6 to 10-3; the greatest response was observed in the oldest age group and the smallest in the youngest one, for all concentrations.