Expulsion mechanism of adult-taeniid cestodes induced by mucosal responses of definitive hosts.

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The taeniids are of interest not only because of their disease roll in domestic animals, some species are also of immense importance to Public health.To date, research on resistance to these cestodes has mainly focused on the intermediate host, and therefore on the larval cestode stage. The reasons for this were, that a suitable definitive host model has not been established, and experiments using the natural definitive host pose a grave threat to liuinan health, creating a barrier to safe investigative methods.To overcome this, this laboratory has investigated the possibility of using as experimental hosts for the five taeniid species Echinococcus multilocularis(Em), E. granulosus(Eg), Taenia crassiceps(Tc), T. saginata(Ts) and T. hydatigena(Th), the rodent species golden hamster(GH), Mongolian gerbil(MG) and 10 species of wild carnivorous rodents obtained from New Mexico, U.S.A.1) Tc/GH group. Adult worms developed in the small intestine of predonisolone treated and imtreated hamster … More s, and produced normal eggs.2) TC/MG group. In the treatment group worm expulsion was hindered as in the GH. A marked impediment to egg formation was noted.3) Em/GH group. Sexually mature worms were recovered from imtreated GH on day 25 post inoculation(PI). In inbred strains the presence of a defensive reaction to reinfection was suggested.4) Em/MG group. Susceptibility varied with age of host, and high worm recovery rate showed that the eggs liad Iiigli infectivity in this 1-iost.5) Em/Kangaroo rat etc. group. In tlie early stages of infection these rodents match the natural definitive host for worm recovery rate and worm development.Also, a complete substitute definitive host model for Em and Tc was established for the first time, and we could begin to explain phenomena such as the association between worm expulsion and antibody response.Apart from this, by achieving growth to sexual maturity of the human tapeworm T. saginata in treated Mongolian Gerbils, we have broken down the barriers to research in this field. Less