pyrantel-tartrate and Trichostrongyloidiasis

Haemonchus contortus- and Trichostrongylus colubriformis-infected jirds (Meriones unguiculatus) are useful for anthelmintic studies. With concurrent infections of these parasites established in the jird, questions of not only anthelmintic activity, but to some extent spectrum, could be assessed in a single model system. This report outlines a model using immunosuppressed (0.02% hydrocortisone in feed) jirds concurrently infected with H. contortus and T. colubriformis. Immunosuppressed jirds were inoculated with approximately 1,000 exsheathed infective larvae of each species, treated per os on day 10 postinoculation (PI), and killed on day 13 PI. Stomachs and small intestines were removed, opened longitudinally, incubated in distilled water at 37 C for 5 hr, fixed in formaldehyde solution, and stored for subsequent examination. Contents of both organs were examined using a stereomicroscope (15-45 x). Various standard anthelmintics were evaluated in the model; modern broad-spectrum ruminant anthelmintics (benzimidazoles, febantel, ivermectin, levamisole hydrochloride, and milbemycin D) are active uniformly and in most cases at doses comparable to those required for efficacy against these parasites in ruminants. This model, using worms of 2 genera living in distinct sites, allows preliminary evaluation of anthelmintic activity and spectrum for experimental compounds in a single cost- and resource-efficient experiment.

Topics: Animals; Anthelmintics; Anti-Bacterial Agents; Benzimidazoles; Bithionol; Diethylcarbamazine; Gerbillinae; Guanidines; Haemonchiasis; Macrolides; Piperazine; Piperazines; Pyrantel Tartrate; Rodent Diseases; Trichostrongyloidiasis

Two experiments were carried out to define the effect of repeated anthelmintic treatments with or without repeated infections by H. polygyrus on the receptivity of the mouse to subsequent infections by the same parasite. The aim of the first experiment was to show the effect of these interventions on the future development of host resistance. This experiment did not reveal a marked difference in behaviour between treated or non-treated animals. During the second experiment a modification of the acquisition of resistance during the period of infections and multiple treatments was looked for. It was shown that multiple treatments of the host during the period of immunity markedly improved the mechanisms of defense against a new infection. Any direct action of anthelmintics was ruled out in explaining this mechanism. Two drugs were compared: pyrantel tartrate and levamisole. No difference has been shown between these two drugs. It is possible, however, that the multiple treatments act by enabling a more intense renewal of the parasitic population and therefore by increasing the stimulus initiating protection.

Topics: Animals; Female; Immunity; Levamisole; Male; Mice; Pyrantel; Pyrantel Tartrate; Trichostrongyloidea; Trichostrongyloidiasis