A study of the pathogenesis of Trichostrongylus colubriformis infection in lambs with observations on the contribution of gastrointestinal plasma loss

A study of the pathogenesis of Trichostrongylus colubriformis infection in lambs with observations on the contribution of gastrointestinal plasma loss. International Journal for Parasitology 3: 743–757. Increased effusion into the gut of⁵¹Cr-labelled plasma protein was observed in 20-week-old Merino lambs which showed signs of trichostrongylosis after administration of 100,000 T. colubriformis larvae. In another trial, similarly infected 12-week-old meat type crossbred lambs did not have elevated gastrointestinal plasma loss, or signs of trichostrongylosis, although they generally carried heavier worm burdens than the Merinos. Differences in breed susceptibility were considered a possible explanation. Nine-week-old Merino lambs inoculated with 85,000 T. colubriformis had increased plasma loss into the gut beginning 10–12 days after infection, coinciding with onset of inappetance, hypoproteinaemia and weight loss. Weight loss was considered largely due to reduced feed intake, but infected lambs during the period of protein effusion into the gut lost more weight, or gained less, than pair fed controls. Hypoproteinaemia was related mainly to effusion of plasma into the gut. One infected lamb, and its pair fed control, died, probably due to malnutrition. Slight anaemia, and depressed faecal dry matter per cent were observed in infected lambs.