Experimental Studies on Trichuris muris in Mice with an Appraisal of Its Use for Evaluating Anthelmintics

Attempts to infect white mice from five commercial sources with Trichuris muris yielded discouraging results. DBA-2 hybrid mice, particularly weanlings, were the most useful experimental hosts among nine types of rodents studied for susceptibility. In these mice, from 10 to 27 per cent of the administered eggs developed. Approximately 1 month was required for the worms to mature, and mature worms persisted for 2 to 3 months. However, the infections appeared to be of limited value in drug screening for trichuricidal activity, since they were refractory to treatment with the known trichuricides: dithiazanine iodide and pyrvinium chloride. Infection of laboratory rodents with Trichuris muris (Schrank, 1788) was first reported by Shikhobalova (1937). He experimentally infected white mice to study the developmental stages, with reference to the use of the worm for chemotherapeutic testing. Tissue reactions to the parasite in the cecum of white mice were described by Efremov and Shikhobalova (1939), and resistance of white mice to superinfection with T. muris was demonstrated by Shikhobalova (1940, 1941). Attempts to induce immunity in mice by oral or parenteral vaccination with extracts of T. muris were reported by Leikina (1944). Previously, T. vulpis in dogs had been the main experimental trichurid infection (Lammler, 1958). The limitations of work with this host, in contrast to a small rodent, are readily apparent. Fahmy (1954) induced T. muris infections in laboratory-reared albino mice with eggs from wild house mice. He described the main points of the life cycle, including the morphogenesis of the larval stages, but failed to disclose the strain of mice used, the proportion of exposed mice that became infected, or the relative susceptibility among strains. Each of these factors may influence decisively the maintenance of the infection on a routine basis in the