PARASITOLOGY - Lungworm Flashcards
What are the two main families of nematode which cause parasitic bronchitis in large animals?
Trichostrongyloidea
Metastrongyloidea
What type of lifecycle do trichostrongloidea have?
Direct lifecycle
List three species of trichostrongyloidea which cause parasitic bronchitis in large animals
Dictyocaulus viviparus
Dictyocaulus arnfieldi
Dictyocaulus filaria
What is the host of dictyocaulus viviparus?
Cattle
What is the infective stage of the dictyocaulus viviparus lifecycle?
L3 larvae
Describe the lifecycle of dictyocaulus viviparus
- L3 larvae are ingested by host
- L3 larvae penetrate the intestinal mucosa and travel to the mesenteric lymph nodes where they moult into L4 larvae
- L4 larvae travel via the blood and lymphatics to the bronchioles where they moult into young adults
- Young adults migrate to the bronchi where they moult into mature adults and produce eggs
- L1 larvae hatch from the eggs and migrate to the lungs and up the trachea where they are coughed up and swallowed
- L1 are shed in the faeces
- L2 and L3 develop in the faeces
What is the pre-patent period (PPP) of dictyocaulus viviparus?
26 days
What is the clinical sign of a mild parasitic bronchitis?
Intermittent cough
What are the four clinical signs of a moderate parasitic bronchitis?
Coughing at rest
Tachypnea
Hyperpnea
Lung crackles
What is tachypnea?
Rapid breathing
What is hyperpnea?
Deep breathing
What are the four clinical signs of a severe parasitic bronchitis?
Harsh cough
Tachypnoea
Hyperpnoea
Open-mouth breathing
When would an individual with parasitic bronchitis also present with pyrexia?
If there is a secondary bacterial infection
What are the four phases of parasitic bronchitis pathogenesis?
Penetration phase
Pre-patent phase
Patent phase
Post-patent phase
Describe the penetration phase of parasitic bronchitis
Between days 1-7, the larvae are migrating to the bronchioles and there are no clinical signs
Describe the pre-patent phase of parasitic bronchitis
Between days 8-25, larvae are migrating through the bronchioles, stimulating an acute inflammatory response and the beginning of clinical signs
Describe the patent phase of parasitic bronchitis
Between days 26-60, the mature adults in the bronchi produce eggs, stimulating hypertrophy of the epithelium, profuse inflammatory response and oedema
Describe the post-patent phase of parasitic bronchitis
Between days 61-90, there will be expulsion of the adult worms due to the actions of the immune response and most animals will begin to recover and gain strong immunity to this infection
What are the five methods that can be used to diagnose dictyocaulus viviparus?
Assess clinical signs
Grazing, vaccination and anthelmintic history
Identify L1 larvae in a faecal sample
ELISA
Bronchioalveolar lavage
Which technique should be used to identify L1 dictyocaulus viviparus larvae in a faecal sample?
Baermann technique
What is re-infection syndrome?
Re-infection syndrome occurs when cattle are exposed to such a heavy infection that their acquired immunity from the initial infection is overwhelmed
What should be done to diagnose re-infection syndrome?
Assess clinical signs
History
In which climate is dictyocaulus viviparus usually found?
Temperate climates with high rainfall
During which months of the year is a dictyocaulus viviparus infection most common?
July to September/October
