Muellerius
- Common, although not major pathogens; little economic importance.
Life-Cycles
- Indirect life-cycle involving mollusc intermediate hosts
- L1 passed in faeces, penetrate foot of mollusc, develop to L3 in 2-3 weeks
- Infected mollusc ingested with grass
- L3 released by digestion and travel to lungs by lymphatic route
- Adults found in alveoli/parenchyma (Muellerius) or small bronchioles (Protostrongylus)
- Prepatent period 6-10 weeks (Muellerius), 5-6 weeks (Protostrongylus)
Epidemiology
- High prevalence because of wide range of intermediate hosts, prolonged survival of larvae in faeces, long periods of patency (>2 years) and poor host immunity
Muellerius capillaris
- Muellerius capillaris common parasite of sheep and goats in respiratory infections
- Common in sheep and goats
- Rarely any clinical significance
- Grossly:
- Multifocal interstitial pneumonia grossly evident as firm "lead-shot" nodules throughout the parenchyma, often with enveloping granulomatous response
- Early stages are reddish in colour, turning later to greyish green, may calcify
- Mostly in dorsal region of caudal lung lobes
- Histologically:
- Damaged alveolar septa with mild fibrous thickening and lymphocytic infiltrate
- In more developed host resistance, foci of eosinophils around larvae, hyperplastic epithelium, macrophages, giant cells
- May be some calcification