SERUM ANTIBODIES IN CANINE ECHINOCOCCOSIS

Specific IgG, IgA and IgE antibodies against E. granulosus protoscolex antigen were detected by enzyme-linked immunosorbent assay (ELISA) in sera from dogs experimentally or naturally infected with E. granulosu s. The specificities of the IgG, IgA and IgE ELISAs were 100, 100 and 97.3%, respectively. Sera from 626 dogs of different categories and ge ographic regions in Australia, Uruguay and Kenya were tested. There we re distinct differences in antibody responses in experimentally infect ed canids and in the number of naturally infected dogs found seroposit ive, depending on geographic region. The overall sensitivities of the ELISA (IgG, IgA and IgE) ranged between 73 and 84%, except for one geo graphic region where it was 54%. Genetic differences of the dogs and/o r antigenic variations of the parasite appear to be responsible for th e variations in specific antibody levels in infected dogs. In average, approximately one third of dogs from hyperendemic hydatid regions, wi thout E. granulosus worms at autopsy or negative for E. granulosus inf ection by arecoline testing, were seropositive for anti-E. granulosus antibodies, suggesting previous infection with or exposure to the para site. The results of this study demonstrate that, although the diagnos is of current intestinal E. granulosus infection on an individual dog basis is not always reliable by serology, serum antibody ELISA is usef ul as an epidemiological/educational tool for seroprevalence studies o n canine echinococcosis.