comparison of the validity of different diagnostic methods in determining hydatidosis in larg ruminants

hydatidosis is caused by the larval stage (metacestode) of the tapeworm echinococcus granulosus. the disease has a worldwide distribution and iran is in the hyperendemic region. in the present study, the efficacy of dot-elisa and pcr tests for detecting hydatid cysts was investigated. blood samples and samples from liver and lung were collected from a number of 256 cattle and 132 water buffaloes. soluble antigen was obtained from hydatid cyst fluids (hcfs) and protoscolices (px) using concentration and sonication procedures. anti hcfs and px were provided from rabbits immunized with soluble antigens. for molecular analysis, dna was extracted from tissue samples and a 688 bp fragment of nda1 gene was amplified. necropsy findings indicated that lung and liver hydatid cyst infection was 18.4% for cattle and 8.3% for water buffaloes. results of dot-elisa test showed that 22.7% of cattle and 11.8% of water buffaloes were seropositive for hydatid cysts. infection rate using molecular detection were 26.1% in cattle and 14.3% in water buffaloes. using necropsy findings as gold standard test, sensitivity and specificity of dot-elisa was 81.01% and 95% for cattle, respectively. whereas sensitivity and specificity was 77.12% and 96.32% for water buffaloes. sensitivity and specifity of pcr test was 97.4% and 99.4% for examined cattle while these indexes were 91.2% and 99% for examined water buffaloes. data analysis showed that there is no significant difference between these two technique (p<0.05).  based on result of this study, dot-elisa technique can be considered as one of the useful methods in the screening of hydatid cyst in cattle and water buffalo.