Pneumonia: Symptoms & Signs

Pneumonia often starts with symptoms typical of a cold or upper respiratory infection, like sore throat, nasal congestion, and cough. As the infection develops in the lung, high fever is apparent along with chills and a cough that produces thick sputum. Chest pain can occur if the outer layer (pleura) of the lungs is involved in the inflammatory process. The skin color may become bluish or purplish if there are insufficient levels of oxygen in the blood. Nonspecific symptoms that can accompany pneumonia include headache, muscle aches, fatigue, and weakness.

Causes of pneumonia

Pneumonia is most often caused by infections that may be bacterial, viral, or sometimes due to fungi or parasitic infections. Streptococcus pneumoniae is the most common bacterial type that causes pneumonia. Influenza and respiratory syncytial virus (RSV) are the most common viral causes of pneumonia. Other bacteria that can cause pneumonia include Mycoplasma pneumoniae, Legionella pneumophila, and Chlamydia pneumoniae. Fungal pneumonia may be caused by Histoplasma capsulatum, Cryptococcus neoformans, Coccidioides immitis, or other types of fungi. Fungal pneumonia and pneumonia due to the parasite Pneumocystis jiroveci are most common in people with compromised immune systems.

REFERENCE:

Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.

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