Allergic reactivity and socio-economic level in a tropical environment.

As some factors associated with the tropical environment can modify the expression of atopic disease, various indicators of allergic reactivity were compared between allergic and non-allergic subjects of different socio-economic level in Caracas, Venezuela (Lat. 10 degrees N). The socio-economic levels considered were high (HSEL), medium-high (MSEL) or low (LSEL). As generally found in temperature climates, in the HSEL the total serum IgE levels of allergic patients were significantly greater than those of non-allergic individuals (geometric means of 274 vs 126 IU/ml, respectively), as were also the specific serum IgE antibody levels (55.6 vs 23.8% positive, respectively, for house dust). These results correlated closely with the skin-test reactivity of these subjects (60.3 vs 17.5% positive for house dust). In this group, the degree of intestinal helminthic infection was low (5.6% positive for Ascaris). In contrast, for the MSEL where the degree of parasitic infection was higher (13.0%), the total serum IgE levels were elevated in both allergic and non-allergic subjects (602 vs 363 IU/ml). Similarly, positivity for specific IgE antibody was high, and comparable between allergics and non-allergics of this group (61.5 vs 54.2%), as was also the case for skin-test reactivity (71.9 vs 60.4%). In the LSEL, parasitic infection was prevalent (47.6%), and the total serum IgE levels were markedly elevated, with little difference occurring between allergic and non-allergic individuals (2269 vs 1981 IU/ml). The positivity for specific IgE antibody was high, and effectively independent of the allergic state (75.6 vs 53.7%), but in contrast the skin test reactivity was relatively low (22.0 vs 9.8%).(ABSTRACT TRUNCATED AT 250 WORDS)