Lungworm is the most common respiratory disase in adult cattle.

Lungworms are nematode worms. Dictyocaulus viviparus is the most common lungworm of cattle; the infection is also known as “Husk” or more technically as “Parasitic Bronchitis”.


LIFE-CYCLE

Adult D. viviparus worms reside in the bronchial tree of the animal's lungs. They lay eggs into the airways (bronchi). These eggs are coughed up and subsequently swallowed by the host. The eggs hatch into larvae in the gastrointestinal tract of the ruminant host.

These larvae are shed in the faeces. In the faeces, larvae mature through two stages and become infective. Cattle faeces are a great place for the growth of Pilobolus fungi. The larvae of Dictyocaulus viviparus invade the inside of these fungi, and wait in the fungal sporangium. When the fungus sporulates, the larvae are dispersed as much as 10 feet in a pasture.

Cattle grazing then ingest the larvae. These larvae go through the intestinal system and penetrate the intestinal wall. They use the lymphatic system to reach the mesenteric lymph nodes, where they use the blood supply and the lymphatic system to reach the lungs, where they become adults.

The life cycle is then completed.
 

CONTROL

The vaccine is an aqueous suspension of Dictyocaulus viviparus larvae which have partially inactivated by ionizing radiation so they cannot complete their life cycle.

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