Protostrongylus rufescens: Red lungworm

General Description: Slender, reddish nematodes, 16 to 35mm 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 faeces. On pasture these larvae must penetrate a snail of the Helicella, Theba, Abida, Zebrina, or Arianta genera. In the snail, they moult 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.

Location: Airways of lungs.

Geographical Distribution: Europe, Africa, Australia, New Zealand, North America.

Significance: 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 faeces.

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