Atlas of livestock parasites
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Bunostomum trigonocephalum



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Bunostomum trigonocephalum

Nematodes with an anterior end that is bent toward its back. The mouth is cup-shaped and has two cutting plates. Males are 12 to 17 mm long with a large bursa. Females are 19 to 26 mm. long.

Life Cycle:

Direct life cycle with infection occurring by either ingestion or skin penetration. Eggs in faces may hatch and reach the infective third larval stage in 5 days. Those that penetrate the host’s skin are carried in blood to the lungs. From here they migrate up the trachea toward the mouth, are swallowed, and develop to the adult stage in the small intestine. The prepatent period is 8 to 10 weeks.


Small intestine.

Geographical Distribution:
Worldwide, especially in warm, moist climates.

Unthriftiness of sheep infected with hookworms makes this parasite a costly one. Damage attributed to Bunostomum is increasing.

Effect on Host:
Adults attach to the intestinal wall and suck blood. Bleeding continues after the worms have finished feeding, making blood loss considerable. Iron-deficiency anemia, edema ("bottle jaw"), and malnourishment occur as with Haemonchus infections. In addition, larvae entering sheep through skin may cause much irritation and itching. This is common in feet and stomach.

Diagnostic Information:
Strongyle-type eggs appear in faces, but may be scarce, even in heavy infections.


Use of well-drained pastures and removal of manure from areas where sheep are kept reduce hookworm populations. Infected animals may be treated with anthelmintics.


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