Difference between revisions of "Dictyocaulosis - Cattle"
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| + | *''Dictyocaulus viviparus'' causes [[Respiratory Parasitic Infections - Pathology#Dictyocaulus viviparus|parasitic bronchitis]] | ||
| + | [[Parasitic Bronchitis - Cattle]] | ||
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| + | [[Image:Dictyocaulus viviparus.jpg|right|thumb|100px|<small><center>Dictyocaulus viviparus (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]] | ||
| + | [[Image:Parasitic bronchitis.jpg|right|thumb|100px|<small><center>Parasitic bronchitis (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]] | ||
| + | *Found in [[Tracheitis#Infectious causes of tracheitis|trachea]] and [[Bronchitis#Infectious causes of bronchitis or bronchiolitis|large bronchi]] | ||
| + | *Causes parasitic bronchitis, synonyms: bovine dictyocauliosis, husk, hoose | ||
| + | *Primary infection: | ||
| + | **Penetration phase (week 1) | ||
| + | ***Larvae migrate to lungs, no clinical signs | ||
| + | **Prepatent phase (weeks 1-3) | ||
| + | ***Development and migration of larvae -> [[Bronchitis#Bronchiolitis|bronchiolitis]] -> eosinophilic exudate -> air passage blocked -> alveolar collapse (distal to blockage) -> clinical signs (tachypnoea, coughing) | ||
| + | **Patent phase (weeks 4-8) | ||
| + | ***Egg-producing mature worms | ||
| + | ***[[Bronchitis|Bronchitis]] - due to mature worms | ||
| + | ***[[Verminous Pneumonia|Parasitic pneumonia]] - due to aspiration of eggs and larvae -> cellular infiltration of [[Neutrophils|neutrophils]], macrophages, giant cells | ||
| + | **Postpatent phase (weeks 8-12) | ||
| + | ***Majority of worms are expelled | ||
| + | ***In 25% of cases clinical signs may reappear as a result of alveolar epithelialisation | ||
| + | ***May be together with [[Pulmonary Emphysema|interstitial emphysema]] and [[Pulmonary Oedema|pulmonary oedema]], or secondary bacterial infection | ||
| + | *Reinfection syndrome: | ||
| + | **Immune cattle show clinical signs only if exposed to large numbers | ||
| + | **Pathogenesis - large numbers of larvae reach bronchioles where they are killed by immune response | ||
| + | **Pathology - parasite granulomata (grey-green, 5mm diameter, macrophages, giant cells, eosinophils) and eosinophilic plugs in bronchioles | ||
| + | <small>Above from RVC Parasitology study guide (2005-2006)</small> | ||
| + | *Preferentially in dorsocaudaland ventrocaudal regions | ||
| + | |||
| + | *Histologically | ||
| + | **Bronchial epithelium may show hyperplasia due to the chronic irritation | ||
| + | **Cross-sections of the parasites | ||
| + | **Exudate contains many eosinophils | ||
| + | **Foci of necrosis in the rest of the lung tissue due to aspiration of eggs and larvae fromhese adults | ||
| + | **In mild infestations, the adults are normally expelled in two months - self cure | ||
| + | *Repeated infestation and secondary bacterial infection are common | ||
| + | |||
| + | *Two other types of lesion in lung tissue due to this worm have been reported: | ||
| + | **Nodules (2-4mm in diameter) with greenish centres in the reinfection of an immune animal - the host mounting a successful defence and preventing larval migration | ||
| + | **Pulmonary oedema and emphysema - thought to be a hypersensitivity response to a massive invasion of larvae in previously- sensitised animals - the gross and microscopic appearance is similar to that of [[Acute Bovine pulmonary Emphysema and Oedema|fog fever]] | ||
| + | |||
| + | |||
| + | [[Category:Respiratory Diseases - Cattle]] | ||
| + | [[Category:Bronchi and Bronchioles - Pathology]] | ||
| + | [[Category:Respiratory Parasitic Infections]] | ||
| + | [[Category:To Do - Kate]] | ||
Revision as of 16:13, 1 March 2011
Clinical
- Dictyocaulus viviparus causes parasitic bronchitis
- Found in trachea and large bronchi
- Causes parasitic bronchitis, synonyms: bovine dictyocauliosis, husk, hoose
- Primary infection:
- Penetration phase (week 1)
- Larvae migrate to lungs, no clinical signs
- Prepatent phase (weeks 1-3)
- Development and migration of larvae -> bronchiolitis -> eosinophilic exudate -> air passage blocked -> alveolar collapse (distal to blockage) -> clinical signs (tachypnoea, coughing)
- Patent phase (weeks 4-8)
- Egg-producing mature worms
- Bronchitis - due to mature worms
- Parasitic pneumonia - due to aspiration of eggs and larvae -> cellular infiltration of neutrophils, macrophages, giant cells
- Postpatent phase (weeks 8-12)
- Majority of worms are expelled
- In 25% of cases clinical signs may reappear as a result of alveolar epithelialisation
- May be together with interstitial emphysema and pulmonary oedema, or secondary bacterial infection
- Penetration phase (week 1)
- Reinfection syndrome:
- Immune cattle show clinical signs only if exposed to large numbers
- Pathogenesis - large numbers of larvae reach bronchioles where they are killed by immune response
- Pathology - parasite granulomata (grey-green, 5mm diameter, macrophages, giant cells, eosinophils) and eosinophilic plugs in bronchioles
Above from RVC Parasitology study guide (2005-2006)
- Preferentially in dorsocaudaland ventrocaudal regions
- Histologically
- Bronchial epithelium may show hyperplasia due to the chronic irritation
- Cross-sections of the parasites
- Exudate contains many eosinophils
- Foci of necrosis in the rest of the lung tissue due to aspiration of eggs and larvae fromhese adults
- In mild infestations, the adults are normally expelled in two months - self cure
- Repeated infestation and secondary bacterial infection are common
- Two other types of lesion in lung tissue due to this worm have been reported:
- Nodules (2-4mm in diameter) with greenish centres in the reinfection of an immune animal - the host mounting a successful defence and preventing larval migration
- Pulmonary oedema and emphysema - thought to be a hypersensitivity response to a massive invasion of larvae in previously- sensitised animals - the gross and microscopic appearance is similar to that of fog fever