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Pneumonia is an inflammatory condition of the lung affecting primarily the microscopic air sacs known as alveoli. It is usually caused by infection with viruses or bacteria and less commonly other microorganisms, certain drugs and other conditions such as autoimmune diseases.〔 Typical signs and symptoms include a cough, chest pain, fever, and difficulty breathing. Diagnostic tools include x-rays and culture of the sputum. Vaccines to prevent certain types of pneumonia are available. Treatment depends on the underlying cause. Pneumonia presumed to be bacterial is treated with antibiotics. If the pneumonia is severe, the affected person is generally hospitalized. Pneumonia affects approximately 450 million people globally per year (7% of the population) and results in about 4 million deaths. Although pneumonia was regarded by William Osler in the 19th century as "the captain of the men of death," the advent of antibiotic therapy and vaccines in the 20th century has seen improvements in survival.〔 Nevertheless, in developing countries, and among the very old, the very young, and the chronically ill, pneumonia remains a leading cause of death.〔 In the terminally ill and elderly, especially those with other conditions, pneumonia is often the immediate cause of death. In such cases, particularly when it cuts short the suffering associated with lingering illness, pneumonia has often been called "the old man's friend."〔 ==Signs and symptoms== People with infectious pneumonia often have a productive cough, fever accompanied by shaking chills, shortness of breath, sharp or stabbing chest pain during deep breaths, and an increased rate of breathing.〔 In the elderly, confusion may be the most prominent sign. The typical signs and symptoms in children under five are fever, cough, and fast or difficult breathing.〔 Fever is not very specific, as it occurs in many other common illnesses, may be absent in those with severe disease, malnutrition or in the elderly. In addition, a cough is frequently absent in children less than 2 months old.〔 More severe signs and symptoms may include blue-tinged skin, decreased thirst, convulsions, persistent vomiting, extremes of temperature, or a decreased level of consciousness.〔〔 Bacterial and viral cases of pneumonia usually present with similar symptoms.〔 Some causes are associated with classic, but non-specific, clinical characteristics. Pneumonia caused by ''Legionella'' may occur with abdominal pain, diarrhea, or confusion, while pneumonia caused by ''Streptococcus pneumoniae'' is associated with rusty colored sputum, and pneumonia caused by ''Klebsiella'' may have bloody sputum often described as "currant jelly". Bloody sputum (known as hemoptysis) may also occur with tuberculosis, Gram-negative pneumonia, and lung abscesses as well as more commonly with acute bronchitis.〔 ''Mycoplasma'' pneumonia may occur in association with swelling of the lymph nodes in the neck, joint pain, or a middle ear infection.〔 Viral pneumonia presents more commonly with wheezing than does bacterial pneumonia.〔 Pneumonia was historically divided into "typical" and "atypical" based on the belief that the presentation predicted the underlying cause.〔 However, evidence has not supported this distinction, thus it is no longer emphasized.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「pneumonia」の詳細全文を読む スポンサード リンク
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