Commonly called the wire worm, this trichostrongyle nematode parasitizes sheep.
Unembryonated eggs are shed in the feces. After a day or two, first stage larvae hatch. The larvae feed on microorganisms in feces and develop to L2 larvae and then L3 larvae, which are still within the sheath of the L2 stage. L3 larvae are ingested with grass while grazing. The sheath is cast off in the definitive site, the abomasum; here the larvae molts two or three more times. In favorable conditions, adult worms develop and feed on the host's blood. Young adults (L4 larvae) can also take blood and cause anemia.
Infected sheep have constipation (more often than diarrhea), weakness, lethargy, and pale mucus membranes. Infected animals are also anemic and may have bottle jaw and chronic weight loss. Heavy infections can be fatal.
This page was last updated on: January 1, 2008
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