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15 Cards in this Set

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Genera of Trichostrongyles found in the abomasum

Haemonchus


Ostertagia


Trichostrongylus (axei)

Common name and main hosts of Haemonchus genus

Barber's pole worm


Sheep, cattle, deer, camel

Haemonchus species

H. contortus


H. placei

Which species occurs in sheep (and rarely cattle)

H. contortus

Which species occurs in cattle (and rarely sheep)

H. placei

Hosts and location of Haemonchus

Sheep/cattle


Abomasum

Features of genus Haemonchus

2-3 cm long (largest in abomasum)


Red


Tooth in buccal capsule


Prominent cervical papillae


"Barber's pole" in female


Female with large vulval flap


Asymmetrical dorsal ray


Spicules with barbs

Life cycle of Haemonchus

Direct


L3 burrows in between abomasal glands and moults to L4


Re-emerge to lumen

Pre patent period of Haemonchus

21 days

Effects on host of Haemonchus

L4 and adult feed on blood


Ingest 0.05ml/worm/day


Microcytic, hypochromic anaemia


Hypoproteinaemia: bottle jaw


Do not cause diarrhoea


Reduced exercise tolerance


Heavy infections: sudden death


Voracious blood sucker

Epidemiology of Haemonchus

High biotic potential (5-10,000 eggs/day)


Eggs will not hatch below 10 degrees


Larvae not resistant to desiccation

Haemonchus in summer rainfall areas

Increase in spring, maximum in february then decline


Overwinter as hypobiotic larvae

Haemonchus in winter rainfall areas

Summers too hot and dry, winter too cool


Develop in spring and autumn


Problems in spring lambs and autumn lambing ewes

Immunity towards Haemonchus

Self cure when threshold reached


Resulting immunity is labile


Do not always get strong immunity to reinfection after self-cure

Vaccine for Haemonchus

Available


Claim to have 75-95% protection used along with antihelmintics