Normal hosts may present with mild chronic respiratory tract symptoms. The presence of fever and leukocytosis is variable. After the initial infection, the organism has a tendency to disseminate, especially in severely immumosuppressed patients.
Nocardia bacteria are common saprophytes in the soil and water.
This bacteria does not commonly colonize the upper respiratory tract. Therefore, when the organism is isolated it should be considered a pathogen. Two species of Nocardia account for most of the disease seen in humans. Nocardiosis also has been described in patients with chronic obstructive lung disease, diabetes, systemic lupus, and pulmonary alveolar proteinosis. Nocardia infection shows both suppurative and granulomatous features.