Schistosomiasis Research Unit, Institute of Biological Sciences, Federal University of Minas Gerais, National Institute for Endemic Diseases, Research Center “René Rachou” (FIOCRUZ), and Department of Animal Sciences, Veterinary School, Federal University of Minas Gerais, C. Postal 2486, 30.000 Belo-Horizonte, Brazil
Histamine diphosphate was injected intradermally, at dilutions of 10-3, 10-4, and 10-5, into 25 boys (10–12 yr old), and 25 men (20–30 yr old) with active schistosomiasis mansoni. A linear relationship between the mean area of the wheals and the logarithm of histamine concentrations was determined. Both equations (men and boys) were significant (P < 0.05) but showed no difference between their regression coefficients. These findings contrast with those obtained with the intradermal test performed with Schistosoma mansoni antigens, in which skin response in men is significantly greater than in boys.