Pneumonia is an infection in one or both lungs. Bacteria and viruses are the most common causes of pneumonia. Fungi can induce pneumonia, too. The infection causes inflammation in the air sacs of the ...

While pneumonia, an infection in the lungs, itself isn’t contagious, the viruses and bacteria that cause it often are. People with weakened immune systems may be at a greater risk from contagious ...

Pneumonia is an inflammation of one or both lungs, typically due to a bacterial, viral, or fungal infection. With pneumonia, the tiny air sacs inside the lungs fill with fluid or pus, leading to ...