Biological parameters of Trichostrongylus colubriformis in Meriones unguiculatus

In a series of three experiments, 64 jirds, Meriones unguiculatus, were inf ected with 700 infective larvae of Trichostrongylus colubriformis for the s tudy of several biological parameters of this laboratory host-parasite mode l. In jirds the third stage larvae of T. colubriformis were shown to reach the fourth larval stage by the Day 6 post-infection(PI). By Day 10 PI, all the worms harvested had reached the immature adult stage. All immature adul t stages of T. colubriformis developed to sexually mature adult stage by Da y 12 PI when the female worms showed developing eggs in their uteri. Develo ped eggs were observed in the uteri of females on Days 13 and 14 PI. The fi rst eggs of I: colubriformis appeared in the faeces of jirds on Day 13 PI. The peaks of egg production were recorded between Day 21 and Day 31 PI. Imm unosuppression of jirds infected with 700 L-3, by administration of dexamet hasone from Day 57 to Day 94 PI led to increased faecal egg count when comp ared to untreated controls. All the worms were located in the small intesti ne. The jirds of dexamethasone treated group harboured higher number of adu lt worms than those of the untreated group. The number of adult worms was s ignificantly higher in the first part of the small intestine than in the th ree other similar parts of the small intestine. The coefficient of correlat ion between the faecal egg count and worm number on the day of necropsy of jirds ranged between r = 0.58 and r = 0.89. Patent infections in jirds were maintained till the end of experiment on Day 100 PI, indicating that in th is host and unlike other laboratory hosts, T. colubriformis is responsible for long lasting infections similar to what happens in domestic ruminants. The results of the present study suggest that the jird is a suitable labora tory model to study various aspects of this host-parasite relationship. (C) 1999 Elsevier Science B.V. All rights reserved.