Lungworms of LA Flashcards
What are the 2 main types of lungworm?
Trichostrongyloidea and Metastrongloidea
What are the types of lung worm that cause disease in cattle, sheep, horses and cervids?
Trichostrongyloidea Cattle - Dictyocaulus viviparus Sheep - Dictyocaulus filaria Equine - Dictyocaulus arnfieldi Cervids - Dictyocaulus eckerti
Describe the lifecycle of Dictyocaulus viviparus
How long are adult lungworm?
< 8cm
What are the clinical signs of parasitic bronchitis?
- Mildly affected animals ( <100 worms) - intermittent coughing
- Moderately affected animals - coughing at rest, tachypnoea (>60bpm), hypernoea (crackles in posterior lung lobes)
- Severely affected animals (> 1000 worms) - harsh cough, tachypnoea (>80bpm), dyspnoea, mouth breathing, pyrexia due to secondary bacterial infection
What are the pathogenic stages?
- Pre-patent stage - larvae migrating through the lungs
- Patent phase - mature adults in airways
What occurs in the prepatent phase?
- L4 and young adults migrate up the resp. tree
- Acute inflammatory response (monocytes, eosinophils)
- Mucus/cellular plugs due to collapse of alveoli
- Clinical signs are first seen
What occurs in the patent phase (26-60d)?
- Clinical signs worsen
- Lesions occur due to worms in bronchi
- profuse inflammatory exudate
- hyperplasia of bronchial epithelium
- overinflation of alveoli
- interstitial emphysema and oedema
- lots of eosinophils
- Lesions due to aspirated eggs/larvae:
- granulomatous response to aspirated eggs
What occurs in the postpaten phase?
- Expulsion of adult worms due to immune response
- Most animals recover gradually and willhave strong aquired immunity
- Some animals - clinical signs will increase (fatal), due to alveolar epithelialisation OR secondary bacterial infection (acture interstitial pneumonia)
How is parasitic bronchitis diagnosed?
- Clinical signs depend on the time of year
- Grazing/vaccination/anthelmintic history
- L1 larvae present in faeces - Baermann technique (not present during prepatent phase)
- Bronchoalveolar lavage see eosinophilia
- ELISA - detects antibody to adult and L3 antigens (reflects exposure to infection)
Describe the epidemiology of lung worm
- Temperate regions with high rainfall
- UK - get disease July to Oct
- L3 can overwinter
- Carrier animals are important
- Sm. no. of L3s can cause infection (100-1000 worms)
- Development of L1 to L3 is rapid in optimal conditions
- Is traditionally the disease of 1st season grazing cattle
What are the preventative measures taken against lungworm?
- Vaccination - Huskvac, vaccinate first season calves before turnout
- Pasture rotation
- Anthelmintics
What are the available treatments for lungworm?
Anthelmintics:
- use early to reduce pathology
- Mildly affected animals - treat and move to clean pasture
- Severely affected animals - house, hydrate NSAIDs, antibiotics if pyretic (treatment may exacerbate clinical signs)
