COMPARISONS OF ELISA AND WESTERN-BLOT ASSAYS FOR DETECTION OF CRYPTOSPORIDIUM ANTIBODY

A seroprevalence survey was conducted using ELISA and Western blot (WB ) assays for antibody to three Cryptosporidium antigens on 380 blood d onors in Jackson County, Oregon. The purpose was to determine if eithe r assay could detect serological evidence of an outbreak which occurre d in Talent, Oregon 6 months earier. The ELISA, which tested for combi ned IgG, IgA and IgM, and the WE, which tested separately for IgG and IgA, detected an almost twofold increase in serological response for p ersons who consumed Talent drinking water during the previous 11 month s. The increases, however, were statistically significant (P < 0.05) o nly for the WE. The identification of serological evidence of infectio n, using sera collected 6 months after the end of the outbreak in a po pulation not selected because of cryptosporidiosis-like illness, sugge sts that assays of Cryptosporidium-specific IgG and IgA may assist in estimating the magnitude of asymptomatic infections in the population.