Haemonchus contortus

CLASS: SECERNENTEA

ORDER: STRONGYLIDA

CHARACTERISTIC STOMA (PHOTO)

CHARACTERISTIC BURSA (DRAWING), (PHOTO)

VERTEBRATE PARASITES

FAMILY: TRICHOSTRONGYLIDAE

Haemonchus contortus

Common name: barber pole worm

Characteristics: Bursa characteristic of the order. Common name is derived from white uteri and ovaries winding around the red blood-filled intestine giving a twisted barberpole appearance.

HEAD (DRAWING)
MALE TAIL (DRAWING)
ADULT (PHOTO)
MALE TAIL (PHOTO)

The copulatory bursa (A) has an asymmetrical dorsal lobe with a Y-shaped dorsal ray (B), which is often confused with the spicules (C).

Importance: This is one example of a large group of parasitic nematodes known as the trichostrongylids which has many genera and species which cause significant economic losses in domestic animals.

Hosts: sheep, goats, cattle, wild ruminants.

Distribution: More prevalent in warm moist regions than in cold, dry areas.

Direct. Adults in abomasum (true stomach).

Eggs pass with feces.

J1 and J2 feed on bacteria in feces.

J3 retain J2 cuticle, do not feed, are eaten by host,

exsheath (lose J2 cuticle) in rumen (anterior to abomasum), then pass to abomasum.

In abomasum molt to J4 and to adult, copulate, lay eggs.

Symptoms/Pathogenicity:

Result from loss of blood and injection of hemolytic proteins into the host (anemia, emaciation, edema, intestinal disturbances).

Management: Drug therapy via drenches, in feed, or in salt.

"Self-cure" - adult worms are spontaneously expelled. Occurs when animals are reinfested at regular intervals. Exsheathment of J3 causes a pH change in the intestine, and adults are unable to hold on.

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