Life cycle of Trichostrongylus retortaeformis in its natural host, the rabbit (Oryctolagus cuniculus).

The chronology of the life cycle of Trichostrongylus retortaeformis (Zeder, 1800) (Nematoda, Trichostrongyloidea) is studied in its natural host Oryctolagus cuniculus. The free living period lasted 5 days at 24 degrees C. Worm-free rabbits were each infected per os with T. retortaeformis larvae. Rabbits were killed at 12 h post-infection (p.i.) and every day from one day to 13 days p.i. By 12 h p.i., all the larvae were exsheathed and in the small intestine. The third moult occurred between 3 and 5 days p.i. and the last moult between 4 and 7 days p.i. The prepatent period lasted 12 to 13 days. The patent period lasted five and a half months. The four known life cycles of species of Trichostrongylus in ruminants were compared with that of T. retortaeformis. No significant difference was found except in the duration of the prepatent period. These similarities in the life cycles confirm the previously formulated hypotheses on the relationship between the parasites of the two host groups (Durette-Desset, 1985).