Haemonchus contortus
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Current revision
Haemonchus contortus
It is very common parasite and one the most pathogenic nematode of ruminants. Adult worms are attached to abomasal mucosa and feed on the blood.
| Kingdom | Animalia |
|---|---|
| Phylum | Nematoda |
| Class | Secernentea |
| Subclass | Rhabditia |
| Order | Strongylida |
| Genus | Haemonchus |
| Species | H. contortus |
| Binomial | Haemonchus contortus |
[edit] Transmission
The adult female worm can release between 5,000 – 10,000 eggs which will be passed out in the feces. Eggs then develop in moist conditions in the feces and continue to develop into the L1 (rhabditiform), and L-2 juvenile stages by feeding on bacteria in the dung. The L-1 stage usually occurs within 4–6 days under the optimal conditions of 24–29 °C. The L-2 rhabditform sheds its cuticle and then develops into the L-3 filiariform infective larvae. The L-3 have a protective cuticle, however under dry hot conditions will not survive long. The L-3 then crawl up the blades of wet grass and wait to be ingested by a grazing animal. Sheep, goats and other ruminants become infected when they graze and eat grasses containing the L3 infecting larvae. The infecting larvae pass through the first three stomachs to reach the abomasum. There the L-3 sheds its cuticle and burrows into the internal layer of the abomasum where they develop into L-4, usually within 48 hours, or pre-adult larvae. The L-4 larvae then molts and develops into the L-5 adult form. The male and female adults mate and live in the abomasum, where they feed upon the blood.
[edit] Pathogenic Activity
The nematode piercing the abomasum causes a number of significant complications in the infected ruminants that can lead to death. The infected animals can display severe dehydration, diarrhea, unthrift appearance, lethargy, depressed low energy behavior, rough hair coat and uncoordinated movements. Furthermore significantly reduced growth and poor reproductive performance has been observed. The accumulation of fluid in the abdomen, gut wall, thoracic cavity and submandibular tissue – a phenomenon commonly called “Bottlejaw”, also is a common association with this infection. Severe blood loss, white mucous membranes, and anemia/PCV are common complications of the infection.
