Stimulation of immune response in dogs against echinococcus granulosus

Abstract

Hydatidosis is a cyclozoonosis that is caused by the larval stage of the cestode Echinococcus granulosus. It is of major veterinary and public health importance in many parts of the world. Several measures are available for its control but mass chemotherapy, using praziquantel is the main method used in dogs. Although the drug used is 100% effective against adult stages of this tapeworm it is not only expensive but also offers no protection against reinfection to treated dogs. Hence, today there exists a great need for the prolonged protection of dogs against this parasite. In the present study vaccination of dogs against Echinococcus granulosus and their response to challenge infections were investigated. Intraperitoneal immunization of sixteen dogs was carried out using dead or live Echinococcus granulosus protoscoleces obtained from hydatid cysts of sheep origin, and later challenged with oral infection of about 34,000 protoscoleces in gelatin capsules. The degree of immunity stimulated was assessed by the rate of worm development and worm burdens in the vaccinated groups as compared to those in controls. Antibodies raised against these protoscoleces were detected using a crude protoscolex antigen in an enzyme linked immunosorbent assay. Results showed that there were no significant differences in the levels of immunity developed by the vaccinated dogs as compared to the controls. Innate resistance was thought to have played a major role in the failure of establishment and development of Echinococcus granulosus worms in these dogs. It is then felt that this line of research utilizing crude protoscolex antigen offers little hope in inducing immunity in dogs against this parasite.