created by Alissa L. Chow for Parasites and Pestilence at Stanford University

from the Oklahoma State University Center for Veterinary Health Sciences

SYNONYMS: trichostrongyloidiasism, trichostrongylosis, trichostrongylus

WHAT: At least 32 species. Looks similar to Hookworm. Causes "black scours" (severe diarrhea) in lambs, occasionally leading to death, but more commonly it causes loss of production. These l osses from Trichostrongylus species infections are not easy to measure because it is commonly present in mixed-species infections, with an additive effect.

WHERE: Small intestine (more common) or abomasum of host.

WHEN: More common in areas with winter rainfall.

IMPORTANCE: It has been estimated that annual losses in the US alone amount to more than $90 million in cattle and $20 million in sheep.  Several species of trichostrongyles have been reported as occasional parasites of humans.

These parasitic worms primarily cause problems in young animals. The presence of the intestinal species cause diarrhea, weight loss and loss of appetite. The worms suck blood from the lining of the intestines which causes irritation and swelling of the intestinal membrane. The damaged mucosa results in malabsorption, impaired digestion and protein loss. Heavy infestations may prove to be fatal to the young animal.