Difference between revisions of "Dictyocaulosis - Cattle"

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

Revision as of 18:50, 19 February 2011

Clinical

Parasitic Bronchitis - Cattle

Dictyocaulus viviparus (Image sourced from Bristol Biomed Image Archive with permission)
Parasitic bronchitis (Image sourced from Bristol Biomed Image Archive with permission)
  • 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)
    • 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
  • 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