Pneumonia is an inflammatory condition of the lung, which primarily affects the small air sacs known as alveoli. It is usually caused by infection with viruses or bacteria and less commonly by other microorganisms, certain medications and conditions such as autoimmune diseases. Pneumonia affects approximately 450 million people globally and results in about 4 million deaths per year. In developing countries, and among the very old, the very young, and the chronically ill, pneumonia remains a leading cause of death.
Other risk factors can include other lung diseases such as cystic fibrosis, COPD, and asthma, diabetes, heart failure, a history of smoking, a poor ability to cough such as following a stroke, or a weak immune system. Also, inhaling food particles or contents from the intestinal tract and some fungi.
Some types of pneumonia can be contagious, so if you are visiting someone that has symptoms, you should take precautions. Infections can be contagious for a few days before symptoms appear and for a few days after. The exact length of time a person is contagious depends on the type of microorganism causing the infection. Some forms of pneumonia, such as pneumonia caused by mycoplasma, remain contagious for several weeks. If a person has pneumonia, they should speak to a doctor about how long the infection will be contagious.
People with bacterial pneumonia will usually be prescribed antibiotics that stop the infection from progressing. Pneumonia will usually stop being contagious a day or two after treatment begins.
A person is also considered contagious during a fever, so it is best to stay home from work or school until the fever is gone. People who have been vaccinated against infections that can cause pneumonia, such as pneumococcal bacteria, are usually immune to those specific germs. Getting the vaccination can help prevent this type of infection from developing. Speak to your Doctor about these vaccinations; they are usually covered by your insurance.