Pneumonia refers to an infection or inflammation of the lung tissue. It is a serious condition, usually caused by any of dozens of viruses and bacteria, often following a severe cold, the flu or bronchitis. Pneumonia can be life-threatening, particularly for people over 65, and anyone with emphysema, chronic bronchitis, heart disease or diabetes.
It's unusual to contract pneumonia from someone else. You will usually develop pneumonia because your immunity is weakened, not because of exposure to germs.
Many pneumonia-causing germs reside in your throat naturally. Normally, your body keeps these germs from entering your lungs and making you sick. But if your immunity is weak, you may not be able to prevent them from entering one or both lungs. Once you've had pneumonia, you're at risk of getting it again.
Symptoms can vary depending on the type of organism causing the problem.
Bacterial pneumonia can cause chills, chest pain, high fever, and a severe cough that produces a rust-colored (bloody) or greenish phlegm. It can be treated with antibiotics.
Viral pneumonia, usually caused by a flu virus, can cause fever, dry cough, headache, muscle pain and weakness, and increasing breathlessness. It is treated primarily with rest. SEEK MEDICAL CARE IF: You have an unexplained fever and/or a persistent cough or breathlessness, particularly following a cold or flu. Be watchful as pneumonia symptoms can be subtle.
Pneumonia becomes deadly when the inflammation in the lungs interferes with breathing; or when the infection enters the bloodstream, spreading to other organs.
Prevention: Because pneumonia is a complication of the flu, getting an annual flu shot can help. People at high risk for getting bacterial pneumonia should discuss getting a one-time pneumococcal vaccine with their health care provider.
Source: Mayo Clinic Family Health Book