Nocardia nova causing pulmonary nocardiosis of black crakes (Limnocorax flavirostra)

Abstract

Natural nocardial infection has been reported in many different species including mammals and fish, but reports in birds remain uncommon. Eight juvenile Black Crakes (Limnocorax flavirostra) died unexpectedly at the Basle Zoo. Necropsy revealed disseminated white, firm nodules, 1-3 mm in diameter, throughout the lung parenchyma. Histologically, the lungs contained multiple, often confluent granulomas with central necrosis. Delicate, gram-positive, 0.5-to l.0-μm-wide, branching, occasionally beaded, filamentous organisms were visible in necrotic centers. These organisms were acid fast when stained with Fite-Faraco. No histologiclesions were seen in other organs. Nocardia nova was isolated from liver. spleen, kidney, and lung. Granulomatous and necrotizing nocardial pneumonia with agonal septicemia was diagnosed, suggesting an aerogenous infection. To our knowledge, this is the first reported epizootic outbreak of nocardiosis in birds, which is additionally unusual because it was caused by N. nova.