Immunoblot analysis of human antibody (IgG) response to S. mansoni antigens extracted with n-butanol from the adult worm membrane fraction. (a) Immunoblot profile of BE with sera (n = 40) from San Sebastián de los Reyes (old endemic site with no transmission since 35 years ago); (b) immunoblot profile of BE with sera of individuals from J.L. Chirinos (n = 12), Caraballeda (n = 10), and Belén (n = 10) infected with the following: T. trichura, A. lumbricoides, S. stercoraris, E. vermicularis, N. americanus, Ancylostoma sp., H. nana, E. histolytica, Entamoeba coli, I. butschlii, E. nana, G. lamblia, and/or B. hominis. Cyst, cysticercosis sera (n = 4); C(-), sera from healthy people (n = 5); C(+), S. mansoni-positive sera (n = 3); CC, conjugate control. Molecular mass markers (in kilodaltons) are shown on the left.