Difference between revisions of "Dictyocaulosis - Cattle"
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m (Text replace - "[[Trachea Inflammatory - Pathology" to "[[Tracheitis") |
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==Clinical== | ==Clinical== | ||
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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: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>]] | [[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 [[ | + | *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 | *Causes parasitic bronchitis, synonyms: bovine dictyocauliosis, husk, hoose | ||
*Primary infection: | *Primary infection: | ||
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***Larvae migrate to lungs, no clinical signs | ***Larvae migrate to lungs, no clinical signs | ||
**Prepatent phase (weeks 1-3) | **Prepatent phase (weeks 1-3) | ||
| − | ***Development and migration of larvae -> [[ | + | ***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) | **Patent phase (weeks 4-8) | ||
***Egg-producing mature worms | ***Egg-producing mature worms | ||
| − | ***[[ | + | ***[[Bronchitis|Bronchitis]] - due to mature worms |
***[[Lungs Inflammatory - Pathology#Verminous pneumonia|Parasitic pneumonia]] - due to aspiration of eggs and larvae -> cellular infiltration of [[Neutrophils|neutrophils]], macrophages, giant cells | ***[[Lungs Inflammatory - Pathology#Verminous pneumonia|Parasitic pneumonia]] - due to aspiration of eggs and larvae -> cellular infiltration of [[Neutrophils|neutrophils]], macrophages, giant cells | ||
**Postpatent phase (weeks 8-12) | **Postpatent phase (weeks 8-12) | ||
Revision as of 16:26, 19 February 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