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Respiratory > Ruminant lungworms > Flashcards

Ruminant lungworms Flashcards

1
Q

What causes bovine lungworm?

A

Dictyocaulus viviparus

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2
Q

Where is Dictyocaulus viviparus found?

A

found in the trachea and larger bronchi –> parasitic bronchitis (husk, hoose)

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3
Q

Other than cattle, what species can Dictyocaulus viviparus affect?

A

farmed deer

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4
Q

Outline immunity to bovine lungworm?

A
  • rapidly acquired

- minimal age resistance

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5
Q

What are the different stages of D. viviparus infection? 4

A
  1. Penetration phase (week 1)
  2. Prepatent phase (weeks 1-3)
  3. ) Patent phase (weeks 4-8)
  4. ) Post-patent phase (weeks 8-12)
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6
Q

What happens in the penetration phase (bovine lungworm)?

A

Week 1 - larvae migrate to lungs, no CS

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7
Q

What happens in the pre-patent phase (bovine lungworm)?

A

Weeks 1-3
Development + migration of larvae –> bronchiolitis –> eosinphilic exudate –> blocks passage of air –> alveolar collapse distal to blockage –> CS (tachypnoea, dyspnoea)

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8
Q

What happens in the patent phase (bovine lungworm)?

A

Weeks 4-8
Worms mature and become egg-producing –> bronchitis (adult worms) and parasitic pneumonia (reaspiration of eggs as larvae –> cellular infiltration by polymorphs, macrophages, FB giant cells)

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9
Q

What happens in the post-patent phase (bovine lungworm)?

A

Weeks 8-12
Period at end of disease when most worms expelled, but CS flare up in 25% cases due to alveolar epithelialisation (alveolar cells replaced by cuboidal cells), interstitial emphysema, pulmonary oedema and secondary bacterial infection

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10
Q

When can cows become reinfected with bovine lungworm?

A

Immune cows only show CS if exposed to massive challenge. Larvae reach lungs but killed by IR. Pathology: parasite granuloma (5mm, grey-green) and eosinophilic plugs in bronchioles)

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11
Q

How can a diagnosis of bovine lungworms be made in calves?

A
  • seasonal (mid-late summer)
  • grazing hx
  • CS
  • Faecal exam (Baerman) –> larval ID
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12
Q

Features of lungworm larva? 3

A
  • short (300 micrometers)
  • blunt tail
  • intestinal GRANULES
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13
Q

Features of GIT larvae

A
  • Longer than lungworm larve (700-1000micrometers)
  • longer tails
  • intestinal CELLS
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14
Q

Which larvae can be present in bovine faeces?

A

Lungworm only. GIT worms shed eggs so only if faecal sample is left unrefrigerated does it have larvae which hatch out of eggs.

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15
Q

how should you do a faecal exam for bovine lungworm?

A

examine healthy and sick animals - all positive samples are potentially significant - carrier animals possible (30% yearlings and 5% cows, also vaccinated cows)

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16
Q

Outline PME findings for bovine lungworm

A
  • lesions on diaphragmatic lobes
  • Plum coloured areas of consolidation
  • Lung perfusion technique to retrieve worms
17
Q

How can you make a diagnosis of bovine lungworm in adult cattle? 7

A
  • season
  • grazing hx
  • CS
  • Faecal exam - Baerman - as for calves
  • Blood and milk ELISA (variable results depending on Ag used, herd results better than individual results)
  • grass examination (larvae around dungpats)
  • response to anthelmintics
18
Q

Outline bovine lungowmr vaccination

A

Bovilis HUSKVAC

  • 1st season calves > 2months old, reared indoors
  • Oral vaccine (irradiated L3)
  • 6 and 2 weeks pre-turnout
  • never mix vaccinated and unvaccinated animals (may increase pasture L3 levels to the point that vaccinated animals’ immunity is overcome)
19
Q

What is an anamestic response?

A

it is a second response to a vaccine (e.g. Bovilis HUSKVAC) where there is an exaggerated Ab response (especially compared to the 1st vaccine where there is a reasonable Ab response)

20
Q

Outline the result of Huskvac vaccination - 3

A
  • lifelong protection following 2 doses (immunity reinforced by field challenge)
  • prevents disease not infection
  • breakdown (overwhelming challenge, improper storage, admin or concurrent disease)
21
Q

Outline anthelmintic control of bovine lungworm

A
  • long residual activity anthelmintics - e.g. doramectin at 0 and 8 weeks post-turnout (5 weeks residual activity against lungworm) but clinical disease may occur if long grazing season.
22
Q

Name 3 ovine lungworm species

A
  • Dictyocaulus filaria*

- Muellerius and Protostrongylus

23
Q

Outline Dictyocaulus filaria LC

A
  • Direct (like D.viviparus)

- PPP 5 weeks (longer than D.viviparus)

24
Q

Outlien Muellerius and Protostrongylus LC

A
  • Indirect (mollusc IH)
  • Adult worms live in alveoli/parenchyma (Muellerius) or small bronchioles (Protostrongylus)
  • PPP 6-10 weeks (Muellerius) or 5-6 weeks (Protostrongylus)
25
Q

Outline pathogenesis of the ovine lungworm species

A
  • DICTYOCAULUS FILARIA - similar to D. viviparus, lesions less widespread as fewer worms
  • MUELLERIUS - nodular lesions contain adult worms, eggs and larvae in lung parenchyma
  • PROTOSTRONGYLUS - adult wroms block small bronchioles –> debris accumulates distal to blockage
26
Q

Diagnosis - ovine lungworms - 4

A
  • Season
  • grazing hx
  • faecal exam (Baerman) - healthy and sick lambs/kids, ID larvae to genus level to differentiate whether Dictyocaulus or not as this is the most pathogenic of the 3 ovine lungworms and to aid prognosis.
  • PME
27
Q

What is the main difference between the larvae of Dictyocaulus filaria and Muellerius spp?

A
  • DICTYOCAULUS - protoplasmic knob on head

- MUELLERIUS - blunt tail with spine

28
Q

What is the PME like for D. filaria?

A

Similar to D.viviparus in cows - lesions mainly in the diaphragmatic lobes and there are plum-coloured areas of consolidation

29
Q

What is the PME like for Muellerius?

A

Palpable nodles (‘lead shot’) on/just below the lung surface (adults worms, eggs and larvae)

30
Q

What is the PME like for Protostrongylus?

A

Adult worms –> block small bronchioles –> debris accumulates distal to the blockage and forms a conical/triangular area of consolidation in the lung

31
Q

Outline control strategies for D.filaria

A
  • difficult, outbreaks unpredictable
  • PGE control measures normally prevent disease
  • OUTBREAK - treat affected, house/move to clean grazing
  • Vaccine - no longer available in UK
32
Q

Outline control strategies for Muellerius and Protostrongylus

A
  • Unlikely to be necessary as NON-PATHOGENIC

- Difficult since wide range of IHs, prolonged survival of larvae in faeces.

Respiratory (34 decks)

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