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Protostrongylus rufescens



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Protostrongylus rufescens
Red lungworm

General Description:
Slender, reddish nematodes, 16 to 35 mm in length.

Life Cycle:
Indirect, with snail as the intermediate host. Adults in airways lay eggs which hatch to first-stage larvae in lungs, migrate up the trachea, are swallowed, and pass out in feces. On pasture these larvae must penetrate a snail of the Helicella, Theba, Abida, Zebrina, or Arianta genera. In the snail, they molt twice and become third-stage, infective larvae. This requires about 12 to 14 days in the snail. Sheep eat snails while grazing; digestion releases the infective larvae which penetrate the intestinal wall and travel in the blood to the lungs where they become adult lungworms.

Airways of lungs.

Geographical Distribution:

Europe, Africa, Australia, North America.

Red lungworms may cause serious disease and death in infected sheep.

Effect on Host:
Pneumonia may be a complication of infection by lungworms.

Diagnostic Information:
Larvae appear in feces.

Protostrongylus spp. larvae

Length 320-400 µm
Posterior half of body may be curled
The features shown are used to confirm diagnosis and to distinguish from free-living and other nematodes that might be present.

Use of well-drained pastures with measures to eliminate snails. Do not graze lambs on pasture following infected stock.


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P.rufescens tail
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