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''Dictyocaulus'' is a genus of nematode parasites of the bronchial tree of horses, sheep, goats, deer, and cattle. ''Dictyocaulus arnfieldi'' is the lungworm of horses, and ''Dictyocaulus viviparus'' is the lungworm affecting ruminants. == ''Dictyocaulus viviparus'': lungworm of cattle, deer== ''D. viviparus'' is the most common lungworm of cattle; the infection is also known as ''husk'' or ''parasitic bronchitis''. Although classified as the same parasite, some people believe that the ''D. viviparus'' of deer and elk should be reclassified as a different species, including ''D. eckertii'' in New Zealand. However, both species have been shown capable of cross-infecting cattle and cervids (at least in New Zealand) . The parasite has a simple but interesting life cycle, with dipersal facilitated by a fungus. 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 Stage 1 larvae (L1) in the gastrointestinal tract of the ruminant host. These L1 larvae are shed in the feces or manure. In the feces, larvae mature through two stages and become infective as L3 stage larvae. Cattle feces supports the growth of ''Pilobolus'' sp. fungi. The L3 larvae of ''D. 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 L3 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 mature once again into L4 stage larvae. The L4 larvae use the blood supply and the lymphatic system to reach the lungs, where they become adults. The life cycle is completed. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Dictyocaulus」の詳細全文を読む スポンサード リンク
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