APPLICATION OF AN IMMUNOASSAY TO DETERMINE RISK-FACTORS ASSOCIATED WITH PORCINE CYSTICERCOSIS IN RURAL-AREAS OF YUCATAN, MEXICO

A Western blot assay for identification of 26 kDa and/or 8 kDa antigen s in a crude saline extract (CSE) of Taenia solium metacestodes, previ ously developed for human cysticercosis, was evaluated for use with pi gs. The test population used for assay standardisation consisted of 45 cysticercotic pigs (5 pigs positive by necropsy and 40 selected by to ngue palpation and LL-Gp immunoblot but not confirmed by necropsy), 48 pigs with heterologous infections and 40 negative controls from endem ic and non-endemic areas. The test detected 93% of the cysticercotic g roup and was 100% specific. In a field study this antigen preparation was compared by immunoblot with antibody recognition for Gp13-50 antig ens in a lentil-lectin semi-purified glycoprotein extract of T. solium (LL-Gp). The seroprevalence to CSE antigen was slightly lower (26/75) when compared to LL-GI! (29/75) and this represented a non-significan t difference. The CSE Western blot assay was used to assess seropreval ence of T. solium cysticercosis in pig populations in the state of Yuc atan, Mexico. A total of 1099 pigs sampled at random from 25 villages revealed a seroprevalence of 23% (253/1099). Seroprevalence in intensi vely reared, farmed pigs was 2% (7/228). In comparison with farmed pig s, the seroprevalence was 33% (172/513) in free-roaming backyard pigs (OR=13.86, CI=4.07-47.22, p<10(-6)) and 25% (74/98) in semi-confined b ackyard pigs (OR=14.03, CI=5.60-35.16, p<10(-6)). There was no signifi cant difference in seroprevalence by sex (p=0.23). Seroprevalence decr eased with age (chi(2)-test for linear trend=7.803, p<0.006). Results of this study demonstrate that the CSE Western blot can be applied for reliable immunodiagnosis of T. solium cysticercosis in pigs. Furtherm ore, variation in pig husbandry in Yucatan indicated significantly hig her exposure to cysticercosis in free-roaming backyard pigs compared t o intensively reared animals from the same area. (C) 1998 Elsevier Sci ence B.V. All rights reserved.