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→Introduction
== Introduction ==
== Introduction ==
''Dictyocaulus viviparus'' causes [[Respiratory Parasitic Infections - Pathology#Dictyocaulus viviparus|parasitic bronchitis]]
[[Parasitic Bronchitis - Cattle]]
[[Parasitic Bronchitis - Cattle]]
Then the prepatent phase lasts 1- 3 weeks and is the development and migration of larvae leading to [[Bronchitis#Bronchiolitis|bronchiolitis]] and then eosinophilic exudate, causing the air passage to be blocked, resulting in alveolar collapse (distal to blockage). This is when clinical signs such as tachypnoea and coughing being to arise.
Then the prepatent phase lasts 1- 3 weeks and is the development and migration of larvae leading to [[Bronchitis#Bronchiolitis|bronchiolitis]] and then eosinophilic exudate, causing the air passage to be blocked, resulting in alveolar collapse (distal to blockage). This is when clinical signs such as tachypnoea and coughing being to arise.
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The patent phase then lasts around 4- 8 weeks and the mature worms produce eggs during this period. Signs of [Bronchitis|Bronchitis]] are seen due to mature worms and [Verminous pneumonia|Parasitic pneumonia]] is seen due to aspiration of eggs and larvae causing cellular infiltration of [[Neutrophils|neutrophils]], macrophages and giant cells.
The patent phase then lasts around 4- 8 weeks and the mature worms produce eggs during this period. Signs of [[Bronchitis|Bronchitis]] are seen due to mature worms and [[Verminous pneumonia|Parasitic pneumonia]] is seen due to aspiration of eggs and larvae causing cellular infiltration of [[Neutrophils|neutrophils]], macrophages and giant cells.
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Finally, the postpatent phase, which lasts around 8- 12 weeks is seen and here, the majority of worms are expelled. In 25% of cases clinical signs may reappear as a result of alveolar epithelialisation, which may occur together with [[Pulmonary Emphysema|interstitial emphysema]] and [[Pulmonary Oedema|pulmonary oedema]], or secondary bacterial infection.
Finally, the postpatent phase, which lasts around 8- 12 weeks is seen and here, the majority of worms are expelled. In 25% of cases clinical signs may reappear as a result of alveolar epithelialisation, which may occur together with [[Pulmonary Emphysema|interstitial emphysema]] and [[Pulmonary Oedema|pulmonary oedema]], or secondary bacterial infection.
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The disease is carried form year to year by overwintering L3 on pasture, as well as carrier animals. Knowledge of the full epidemiology of the disease is not yet understood. Calves pick up the overwintered L3 on pasture and a patent infection occurs producing L1 on the pasture. These migrate from the dungpat via fungus (Pilobolus) and the rest of the calves then become infected. There may be multiple cycles in one year. Immunity however, is rapidly acquired.
The disease is carried form year to year by overwintering L3 on pasture, as well as carrier animals. Knowledge of the full epidemiology of the disease is not yet understood. Calves pick up the overwintered L3 on pasture and a patent infection occurs producing L1 on the pasture. These migrate from the dungpat via fungus (Pilobolus) and the rest of the calves then become infected. There may be multiple cycles in one year. Immunity however, is rapidly acquired.
== Signalment ==
== Signalment ==