Antibody responses and resistance against Ascaris lumbricoides infection among Venezuelan rural children: the influence of ethnicity.

We studied the production of anti parasite antibodies and the resistance against A. lumbricoides infection among the school population of three different Venezuelan ethnic groups: Warao Amerindians, Afro- Americans and white 'Creole' descendents. The prevalence and intensity of A. lumbricoides were determined before and after 1 year of anthelminthic treatment. Parasitic loads were associated to pre-treatment serum levels of anti A. lumbricoides IgE and IgG4 antibodies. The intensity of the infection and the proportion of re-infected children were significantly lower (p < 0.0001) among the Warao Amerindians, exhibiting higher levels of IgE (p < 0.0001) and lower levels of IgG4 (p < 0.0001) compared to their non-Amerindian counterparts. IgE levels correlated inversely with the proportion of re-infected children, whereas the levels of IgG4 were positively associated. These results suggest that ethnicity may influence the balance of IgE/IgG4 levels, modulating the intensity of A. lumbricoides and the resistance to the infection.