Respiratory Parasites I Flashcards
Name three Dictyocaulus lungworms
- D.viviparous- cattle
- D.filaria- Sheep
- D.arnifieldi- horses/ donkeys
What does dictyocaulus viviparous cause?
Causes parasitic bronchitis in cattle
What does dictyocaulus viviparous require to survive?
Wet, mild climate and permanent pastures
What do the dictyocaulus vivparous worms look like?
Adult worms (4-8cm) in trachea and bronchi
What are the four lifecycle phases?
- Penetration phase
- Pre-patent phase
- Patent phase
- Post-Patent phase
What does parasitic bronchitis look like in the pre-patent and patent phase?
Worms and frothy white mucus in the bronchi
What does parasitic pneumonia look like in the pre-patent and patent phase?
Aspiration of eggs into the alveoli
coughing, increased breathing rate, laboured breathing, anorexia
What are the clinical signs in the post-patent phase?
- Inflamed tissues
- flare-ups can be fatal ‘
- aspiration of dead/ dying material
- secondary bacterial infection goes on to cause pneumonia
What are some of the economic consequences of lung worms?
- Reduction in milk in the dairy herd
- Potential deaths
- Recovery takes 10-20 days
What is the epidemiology of dictyocaulus
Larval development and dispersal is dependent on
* Mild temperature
* High rainfall
* Permanent pasture
* Presence of Pilobilus fungi- grows on cow pats
What are some of the risk factors of lungworms?
- Wet summers
- Heavy stocking densities
- Host age/ immunity
How is immunity acquired?
It is rapidly acquired under field conditions
What are the two major components of immunity?
- Decrease in larvae reaching the lungs
- Destruction of adult worms that have reached the lungs, this can be remembered for 2 years
What is re-infection syndrome?
- Immunity to larvae reaching the lungs can wane
- If cattle return to heavily-infected pasture they can be re-infected
- longer-lasting immune response -> hypersensitivity response and acute illness
What is the treatment for lung worms?
- Rapid use of anthelmintics
- Treated cattle are then transferred to clean pasture
- Prognosis depends on disease severity
- Supportive therapy for those severley effected
What is D.filaria in sheep like?
- Pathology and epidemiology is similiar to viviparus
- Clinical signs are less common- coughing and unthriftiness
- Control is acheived by strategies used to manage worms
What is D.arnifieldi in sheep and donkeys like?
- Infection is much more prevalent in donkeys than horses
- Infection in older horses -> coughing, nasal discharge, increased respiration
- Control- avoid co-grazing
What are the typical features of metastrongylus?
- found in lungs and associated blood vessels
- indirect lifecycle
- larvae found in faeces
- Definitive hosts = pigs, sheep, dogs, cats etc.
- kinky tails
What are the main features of angiostrongylus vasorum?
- Called lungworm or ‘french heartworm’
- Adults = 2.5cm long
- PPP =6-8 weeks
- Infections last over 2 years
What is the epidemiology of angiostrongylus vasorum
- Worldwide but data is patchy
- Wild canids are the reservoir hosts
- Infection is more common in younger dogd
What is the pathogenesis of metastrongyles?
- they are poorly understood
- inflammatory response to eggs and larvae causes granulomas, haemorrhage and fibrosis
- therefore there is blockage of blood vessels by adults, larvae and eggs
What are the common clinical signs of metastrongyles?
- Pulmonary
- Coagulopathy
- Cardiovascular
- Neurological signs
- Death
What is the name of the fungi that assists in D. viviparous transmission?
Pilobolus fungi
How does fungi assist in viviparous transmission?
- Larvae migrate up the stalks of the fungi
- Larvae are then projected up to 3m when the seed capsule is discharged
Name three risk factors for viviparous
- Heavy stocking densities
- Wet summers
- Host age/ immunity
What calves are most affected by viviparous?
dairy or dairy cross calves
How long does the patent viviparous infection last?
Does not last longer than 2-3 months
When may cattle become re-infected?
If cattle return to heavily contaminated pasture
What are the main clinical signs of D.filaria in sheep?
Coughing and unthriftiness
