Prevalence of antibody to Borrelia burgdorferi by indirect fluorescent antibody assay, ELISA, and western immunoblot in healthy adults in Wisconsin and Arizona.

The prevalence of antibody to Borrelia burgdorferi in healthy adults from Wisconsin and Arizona was determined by indirect fluorescent antibody assay (IFA), ELISA, and Western immunoblotting. A total of 301 sera from adult volunteer blood donors were collected from three areas of Wisconsin and compared with 49 consecutive anonymous adult volunteer donor sera from Tucson, Arizona, an area without reported Lyme borreliosis. Regional differences in seropositivity were found for Western immunoblotting (34[11%] of 301 from Wisconsin and none of 49 from Tucson; P less than .01) but not IFA or ELISA. No correlation was found among Western immunoblotting and IFA or ELISA results. For persons living in Madison or Milwaukee, Wisconsin (cities not endemic for Lyme borreliosis), 19 (86%) of 22 with a positive Western blot, but only 12 (48%) of 25 with a positive IFA or ELISA, had a significant exposure risk to B. burgdorferi-infected Ixodes dammini (odds ratio, 6.9; 95% confidence interval, 1.4-43.5). Western blot results were consistent with epidemiologic exposure to B. burgdorferi and implied frequent asymptomatic infection among healthy adults living in or visiting areas endemic for Lyme borreliosis.