Pneumonia

Pneumonia is usually caused by infection with viruses or bacteria, and less commonly by other microorganisms.^[a] Identifying the responsible pathogen can be difficult. Diagnosis is often based on symptoms and physical examination.^[8] Chest X-rays, blood tests, and culture of the sputum may help confirm the diagnosis.^[8] The disease may be classified by where it was acquired, such as community- or hospital-acquired or healthcare-associated pneumonia.^[18]


Risk factors for pneumonia include cystic fibrosis, chronic obstructive pulmonary disease (COPD), sickle cell disease, asthma, diabetes, heart failure, a history of smoking, a poor ability to cough (such as following a stroke), and a weak immune system.^[5][7]


Vaccines to prevent certain types of pneumonia (such as those caused by Streptococcus pneumoniae bacteria, linked to influenza, or linked to COVID-19) are available.^[10] Other methods of prevention include hand washing to prevent infection, and not smoking.^[10]


Treatment depends on the underlying cause.^[19] Pneumonia believed to be due to bacteria is treated with antibiotics.^[11] If the pneumonia is severe, the affected person is generally hospitalized.^[19] Oxygen therapy may be used if oxygen levels are low.^[11]


Each year, pneumonia affects about 450 million people globally (7% of the population) and results in about 4 million deaths.^[12][13] With the introduction of antibiotics and vaccines in the 20th century, survival has greatly improved.^[12] Nevertheless, pneumonia remains a leading cause of death in developing countries, and also among the very old, the very young, and the chronically ill.^[12][20] Pneumonia often shortens the period of suffering among those already close to death and has thus been called "the old man's friend".^[21]