- MULTIFOCAL TO COALESCING GRANULOMATOUS AND EOSINOPHILIC INTERSTITIAL PNEUMONIA
- MUELLERIUS CAPILLARIS
- Armed Forces Institute of Pathology
- Muellerius capillaris is a common small (12 -24 mm adults) lungworm of goats and sheep, which is not visible grossly. Infection with this nematode is often characterized by nodular inflammation with eosinophils and giant cells; however, the inflammation depends on the amount of larvae/adults present in the alveoli. Eggs are rapidly hatched and first-stage larvae are found in alveolar spaces. These are coughed up, swallowed and eventually found in the feces. Intermediate hosts are snails and slugs and the life cycle of the nematode is completed when the ruminant digests the intermediate host. Less severe or early infections are often restricted to the dorsal regions of the caudal lung lobes. Typically, alveoli contain a mixture of adults, larvae and eggs, which also may be present in mucus plugs within airways. Interestingly, goats infected with Muellerius will develop a diffuse interstitial pneumonia, but not the characteristic nodules.