The golden hamster as a definitive host of Taenia solium and Taenia saginata.

Immunosuppressants have been extensively used to increase the susceptibility of various laboratory animals to several species of nematodes (Campbell , 1963; 1968; Campbell & Collette, 1962 ; Di Netta , Katz & Campbell , 1972 ; Miller, 1966; Mougeot & Lancastre, 1970 ; Parker, 1961; Ritterson, 1959 ; Wiest, 1972; Wakelin, 1970). Only a few of these compounds have been used to increase susceptibility to cestodes. Corticosteroids were used by: Verster (1971) to increase the susceptibility of golden hamsters to Taenia solium and Taenia saginata; by Ritterson (1971) in Chinese hamsters and by Moss (1972) in mice for Hymenolepis microstoma and by Hopkins, Subramanian & Stallard (1972) in mice for Hymenolepis diminuta. The latter authors found that mice treated with anti-lymphocytic serum (ALS) did not reject H. diminuta 9 to 12 days after infestation while Okamoto & Koizumi ( 1972) showed that antithymocytic serum (ATS), but not ALS, abolished the acquired immunity of mice to Hymenolepis nana. Although mice t reated with the anti-metabolite methotrexate did not expel H. diminuta, these ceased to grow after 16 days (Hopkins et a!., 1972). In rats neither cortisone nor methotrexate prevented destrobilation of H. microstoma which usually occurs after nine days (Goodall, 1972). Mice fed either an antihistamine drug or an antiserotonin drug or one possessing both properties, had heavier burdens of Trichinella spira!is 17 and 21 days after infestation than untreated mice (Campbell , Hartman & Cuckler, 1963). When guinea pigs infested with Trichostrongylus co!ubriformis are treated with antihistamines the development of resistance is suppressed and the paras ites are not rejected (Rothwell Dineen & Love, 1971). Verster ( 1971) showed that golden hamsters treated with Depo-Medrol(l) are markedly more susceptible to infestation with T. solium than with T. saginata. Their susceptibility to T. so/han is directly correlated with the amount of Depo-Medrol administered. The rate of differentiation of the genitalia of the tapeworms is primarily dependent on the amount of immunosuppressant used but is also influenced by the number of worms present in a host. Despite the fact that the tapeworms developed to sexual maturity they did not become patent. 1 mmunosuppression, however, also increased the susceptibility of hamsters to various infections and this influenced the period they could survive such treatment.