SEROLOGY AS AN INDICATOR OF TAENIA-SOLIUM TAPEWORM INFECTIONS IN A RURAL-COMMUNITY IN MEXICO

Serial stool examinations were carried out on a sample of 516 persons living in the town of El Salado (1993 inhabitants). In a group of 40 families (198 individuals), selected by random sampling, there were 2 cases of Taenia solium infection (1·2%); an additional group of 67 families (318 individuals), who volunteered for the study, had 4 cases (1·1%). 5 of the 6 T. solium cases were clustered in 4 neighbouring households. Serum antibodies to the larval stage of T. solium were detected by ELISA using bladder fluid as antigen. 22 members of the random sample group were positive (11%); 58 persons of the total sample of 478 were positive (12%). 43% of individuals living in the same household as a T. solium-infected person were positive, compared to 8·6% seropositive individuals among those not known to have been in daily contact with a T. solium carrier. Odds ratio analysis of the random and total samples showed that the risk of being seropositive when living in the same household as a tapeworm carrier was 9·05 and 6·85 respectively. The results showed a significant correlation between T. solium tapeworm clusters and higher seropositivity rates among contacts rather than among non-contacts. The immune response is a sensitive indicator of a tapeworm infection in a household or family, and is easier to determine than the traditional search for taeniid eggs in stool, a method which is difficult to apply in developing countries due to lack of trained personnel. We conclude that the use of a serological test for the detection of T. solium endemic rural communities would help central and local health authorities in the rational planning of control measures in countries where this zoonosis continues to be an important health problem. © 1990, Royal Society of Tropical Medicine and Hygiene. All rights reserved.