Respiratory Parasites I Flashcards
Lungworms (nematodes)
Dictyocaulus
Cattle lungworm
Dictyocaulus viviparus
Sheep lungworm
Dictyocaulus. filaria
Horse/donkey lungworm
Dictyocaulus. arnifieldi - disease in horses but rare in donkeys (donkeys more commonly infected but don’t display disease symptoms)
Dictyocaulus vivparus (6)
Life cycle of Dictyocaulus viviparus (9)
Penetration phase, pre-patent phase, patent phase, post-patent phase
- L1 larvae shed in faeces -> moult
- L2 in faeces -> moult
- L3 larvae:
- Migrate onto pastures and picked up by other cattle
- Disseminated by rain splash (raindrops)
- Disseminated by pilobolus fungi
- L3 ingested by cattle
- L3 migrate to blood/lymph system then lungs -> moult
- L4 in lungs -> moult
- L5 in lungs
- Adult worms in cattle live in main respiratory passages (trachea + bronchi)
- Female lay eggs in bronchi:
- Hatch almost immediately -> L1
- Get coughed up and then swallowed into the gut -> faeces = sluggish, brown food granules
- L1 -> L3 in 5 days under optimum conditions (wet + mild climate)
What does the penetration phase of Dictyocaulus viviparus involve? (5)
- 0-7 days post-infection (PI)
- L3 ingested
- Migrates to lymph nodes
- Moults to L4
- Bloodstream → Lungs
What does the pre-patent phase of Dictyocaulus viviparus involve? (5)
- 8-25 days PI
- L4 → alveoli
- Moults to L5
- Migrates → bronchi
- Matures to adult
What does the patent phase of Dictyocaulus viviparus involve? (3)
- 26 – 55 days
- PI Adult worms in upper respiratory tract
- L1 in faeces
What does the post-patent phase of Dictyocaulus viviparus involve? (3)
- 55 days PI
- Immune expulsion of worms = strong response
- Larval development can arrest
Pathogenesis and clinical signs of the pre-patent and patent phase (4)
Pathogenesis and clinical signs of the post-patent phase (5)
Cow with husk - severely affected by lungworm, may be reluctant to move, hold their head down, neck extended
Economic consequences of Dictyocaulus viviparus (5)
Epidemiology of Dictyocaulus viviparus - what is larval development and dispersal dependent on? (6)
Seasonality of Dictyocaulus viviparus (8)