The bacteria are carried by air contaminated with soil dust and are breathed into the lungs. In rare cases, the bacteria enter the body by being swallowed or by passing through the skin. Chronically ill people and those receiving drugs that suppress the immune system are at increased risk for nocardiosis. However, about half of the people with nocardiosis, usually the elderly, have no preexisting disease. Symptoms Nocardiosis often begins as a lung infection, such as pneumonia.
Abscesses develop in or beneath the skin in about a third of the cases.
With pneumonia caused by Nocardia , the most common symptoms are a cough, general weakness, chills, chest pain, shortness of breath, fever, loss of appetite, and weight loss. These symptoms are similar to those of tuberculosis or other types of bacterial pneumonia. About a third of people with nocardiosis develop brain abscesses and experience severe headaches and altered sensations or weakness. The part of the body that becomes weakened depends on where in the brain the abscess is located. The diagnosis of nocardiosis is based on identifying Nocardia asteroides in samples of body fluid or tissue taken from an infected person.