Duration of Infection of Jirds (Meriones unguiculatus) with Trichostrongylus colubriformis

Jirds (Meriones unguiculatus) were infected with 700 infective larvae (L3) of Trichostrongylus colubriformis. The fecal egg counts (epg) were followed regularly until 340 days postinoculation, and worm numbers were determined on necropsy at 315 and 350 days postinoculation. The epg increased to a peak of 2,600 on day 24 postinoculation. Thereafter, the epg showed continuous decrease from day 31 until day 318 postinoculation. The rates of inoculum recovery were 0.29–1.43% on day 315 and 0.142–0.428% on day 350 postinoculation. On day 315 postinoculation, 12 male worms were recovered from 2 of 3 animals necropsied. On day 350 postinoculation, all 6 animals were infected, and 6 female and 4 male worms were recovered. The systemic IgM, IgG, and intestinal mucous IgA responses were significantly higher in infected groups compared with negative control groups necropsied on 315 and 350 days postinoculation (P < 0.001). These results confirm that the T. colubriformis–jird system is a useful model for studies on the various host–parasite relationships of chronic trichostrongylosis.