Intradermal test with histamine in schistosomiasis mansoni.

: 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 less than 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.