Pneumonia is an inflammatory illness of the lung. Frequently, it is described as lung parenchyma/alveolar inflammation and abnormal alveolar filling with fluid. (The alveoli are microscopic air-filled sacs in the lungs responsible for absorbing oxygen from the atmosphere.) Pneumonia can result from a variety of causes, including infection with bacteria, viruses, fungi, or parasites, and chemical or physical injury to the lungs. Its cause may also be officially described as idiopathic—that is, unknown—when infectious causes have been excluded.
The viruses and bacteria that cause pneumonia are contagious and are usually found in fluid from the mouth or nose of an infected person. Illness can spread when an infected person coughs or sneezes on a person, by sharing drinking glasses and eating utensils, and when a person touches the used tissues or handkerchiefs of an infected person.
Some cases of pneumonia are contracted by breathing in small droplets that contain the organisms that can cause pneumonia. These droplets get into the air when a person infected with these germs coughs or sneezes. In other cases, pneumonia is caused when bacteria or viruses that are normally present in the mouth, throat, or nose inadvertently enter the lung. During sleep, it is quite common for people to aspirate secretions from the mouth, throat, or nose. Normally, the body’s reflex response (coughing back up the secretions) and immune system will prevent the aspirated organisms from causing pneumonia. However, if a person is in a weakened condition from another illness, a severe pneumonia can develop.
The initial symptoms of viral pneumonia are the same as influenza symptoms: fever, a dry cough, headache, muscle pain, and weakness. Within 12 to 36 hours, there is increasing breathlessness; the cough becomes worse and produces a small amount of mucus. There is a high fever and there may be blueness of the lips.
There are many kinds of pneumonia ranging in seriousness from mild to life-threatening. Pneumonia acquired while in the hospital can be particularly virulent and deadly. Although signs and symptoms vary, many cases of pneumonia develop suddenly, with chest pain, fever, chills, cough and shortness of breath. Infection often follows a cold or the flu, but it can also be associated with other illnesses or occur on its own.
Pneumonia usually starts when you breathe the germs into your lungs. You may be more likely to get the disease after having a cold or the flu. These illnesses make it hard for your lungs to fight infection, so it is easier to get pneumonia. Having a long-term, or chronic, disease like asthma, heart disease, cancer, or diabetes also makes you more likely to get pneumonia.
People who have trouble swallowing are at risk of aspiration pneumonia. In this condition, food, liquid, or saliva accidentally goes into the airways. It is more common in people who have had a stroke, Parkinson’s disease, or previous throat surgery.
Preventing pneumonia is always better than treating it. The best preventive measures include washing your hands frequently, not smoking, and wearing a mask when cleaning dusty or moldy areas. There is a vaccine for pneumococcal pneumonia, a bacterial infection which accounts for up to a quarter of all pneumonias.
There are several ways to keep from getting pneumonia. One is to get all your shots because one of them can help to prevent a type of pneumonia called pneumococcal (say: new-mo-cock-al) pneumonia. Getting a flu shot can also help guard against getting pneumonia, particularly in kids who have asthma or certain other lung conditions. Getting enough rest is also very important because lack of sleep may make it harder for your immune system to fight infections.