VPA 211: General Veterinary Parasitology and Helminthology (3+1)

GENUS: PROTOSTRONGYLUS RUFESCENS

Genus: Protostrongylus rufescens

Location: Small bronchioles
Host: Sheep, goats and deer
Morphology: The male is 16-28 mm long and female is 25-35 mm long.

• The spicules are 0.26 mm long, tubular, with broad membranous expansions.
• The vulva opens near the anus.
• The eggs are unsegmented when they are laid and measure 75-120 by 45-82 µm.

Life cycle:

• The eggs develop in the lungs of the host and the first stage larvae which is passed in the faeces.
• The life cycles requires intermediate host snail species viz. Helicella, Theba, Abida, Zebrina, Arianta. The first stage larvae penetrate the foot of the snail and development takes place in two weeks time with two moulting takes place.
• The final host infected on ingestion of snail along with food and the larvae pass to the lungs of the host via mesenteric lymphatic glands, in which the third ecdysis takes place.

Pathogenesis:

• The worms live in the small bronchioles.
• They produce a local area inflammation, the inflammatory process spreads to the peribronchial tissues.
• The affected alveolar and bronchial epithelium is desquamated, blood vessels are occluded and an infiltration with round cells and proliferation of connective tissue takes place in the area.

Diagnosis: Finding the eggs in faeces.

Treatment: Levamisole-20mg/kg, ditrazine-100mg/kg both given subcutaneously, fenbendazole-20-80 mg/kg, albendazole-5mg/kg.