The Use of Excretory and Secretory Antigens of the Scolex of Taenia ovis for the Serodiagnosis of Infection in Dogs

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Abstract
The excretory and secretory antigen from the evaginated scoleces of T. ovis were collected for 3 days in vitro, and used in an ELISA [enzyme linked immunosorbent assay] test to detect antibodies to T. ovis in the serum of dogs. When tested on sequentially collected sera, diagnostic ELISA values could be detected in many dogs 4 wk after infection, and remained for an average of a further 4 wk after worms were removed from dogs with an anthelmintic. Using an ELISA discriminant value that eliminated all false positives from 70 uninfected laboratory dog sera and from 57 uninfected farm dog sera, 54/62 true positives were found in sera from dogs infected with various numbers of T. ovis for various intervals. Sera from dogs infected with T. hydatigena gave 11/15 false positive reactions, whereas sera from 15 dogs infected with Echinococcus granulosus or 7 dogs infected with T. pisiformis were all negative. For T. ovis the test had a high repeatability, was not greatly influenced by the number of worms carried by the dog and higher titers were correlated with long-standing infections. Approximately 1000 scoleces could be recovered from each experimentally infected sheep. Using the ELISA test with undiluted antigen and serum diluted 1:40, .apprx. 10 sera could be tested in duplicate with the excretions and secretions from each T. ovis scolex.