Difference between revisions of "Dictyocaulosis - Cattle"
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***Egg-producing mature worms | ***Egg-producing mature worms | ||
***[[Bronchitis|Bronchitis]] - due to 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) | **Postpatent phase (weeks 8-12) | ||
***Majority of worms are expelled | ***Majority of worms are expelled | ||
| Line 38: | Line 38: | ||
*Two other types of lesion in lung tissue due to this worm have been reported: | *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 | **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 [[ | + | **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]] |
Revision as of 18:50, 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