RELATED STORIES • Walking pneumonia ASTHMA & RESPIRATORY SYSTEM Emphysema • Bronchitis • Pneumonia • Pleurisy • Sarcoidosis • Cystic fibrosis • Emphysema • Respiratory syncytial virus • Pulmonary embolism • Bronchiolitis • Asbestosis • Interstitial lung disease ASTHMA & RESPIRATORY SYSTEM Respiratory System • Bronchitis • Pneumonia • Pleurisy • Respiratory syncytial virus • Bronchiolitis

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Every year, more than 60,000 Americans die of pneumonia — an inflammation of the lungs usually caused by infection with bacteria, viruses, fungi or other organisms. Pneumonia is a particular concern for older adults and people with chronic illnesses or impaired immune systems, but it also can strike young, healthy people. Worldwide, it's a leading cause of death in children, many of them younger than a year old.

There are more than 50 kinds of pneumonia ranging in seriousness from mild to life-threatening. 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 also can be associated with other illnesses or occur on its own.

Although antibiotics can treat some of the most common forms of bacterial pneumonias antibiotic-resistant strains are a growing problem. For that reason, and because the disease can be very serious, it's best to try to prevent infection in the first place.

Pneumonia can be difficult to spot. It often mimics a cold or the flu, so you may not realize you have a more serious condition. What's more, signs and symptoms can vary greatly, depending on any underlying conditions you may have and the type of organism causing the infection:

• Bacteria. Dozens of types of bacteria can cause pneumonia. Bacterial pneumonia can occur on its own, or you may develop it after you've had a viral upper respiratory infection such as influenza. Signs and symptoms, which are likely to come on suddenly, include shaking chills, a high fever, sweating, chest pain (pleurisy) and a cough that produces thick, greenish or yellow phlegm. Ironically, high-risk groups such as older adults and people with a chronic illness or compromised immune system are likely to have fewer or milder symptoms than less vulnerable people do. And instead of the high fever that often characterizes pneumonia, older adults may even have a lower than normal temperature.
• Viruses. About a dozen different viruses can cause pneumonia. Viral pneumonia strikes primarily in the winter and tends to be more serious in people with cardiovascular or lung disease. It usually starts with a dry (nonproductive) cough, headache, fever, muscle pain and fatigue. As the disease progresses, you may become breathless and develop a cough that produces a whitish phlegm. When you have viral pneumonia you run the risk of also developing a secondary bacterial pneumonia.
• Mycoplasma. This tiny bacterium causes signs and symptoms similar to those of other bacterial and viral infections, although symptoms appear more gradually and are often mild and flu-like. If you've been told you have "walking pneumonia," it's probably caused by mycoplasma. You may not be sick enough to stay in bed or to seek medical care, and may never even know you've had pneumonia. Mycoplasma pneumonia spreads easily in situations where people congregate and is common in child-care centers and among school children and young adults. It may account for as many as one-third of childhood cases. Mycoplasma pneumonia responds well to treatment with the appropriate antibiotics, although you may continue to have a dry, nagging cough during your convalescence.
• Chlamydia. This bacterium causes symptoms similar to those of mycoplasma pneumonia. Although everyone is at risk, chlamydia pneumonia is most common in school-age children. When it does strike older adults, it can be particularly serious, though it does respond to antibiotics. Although the name is the same, the chlamydia bacterium that causes pneumonia isn't the same bacterium that causes sexually transmitted infections.
• Fungi. Certain types of fungus also can cause pneumonia, especially Histoplasma capsulatum, which is common in the and Ohio River valleys and spreads in bird droppings. Most people experience few if any symptoms after inhaling this fungus, but some develop symptoms of acute pneumonia, and still others may develop a chronic pneumonia that persists for months.
• Pneumocystis carinii. Pneumonia caused by P. carinii is the most common opportunistic infection affecting Americans living with AIDS. People whose immune systems are compromised by organ transplants, chemotherapy, or treatment with corticosteroids or other immune-suppressing drugs such as tumor necrosis factor (TNF) inhibitors also are at risk. The signs and symptoms of Pneumocystis carinii pneumonia (PCP) include a cough that doesn't go away, fever and trouble breathing. In the past, P. carinii was considered a type of parasite, but more recent studies suggest that this microorganism is more closely related to fungi.

Your lungs are two spongy organs surrounded by a moist membrane (the pleura). When you inhale, air is carried through the windpipe (trachea) to your lungs in two major airways called bronchi. Inside your lungs, the bronchi subdivide nearly 20 times into a million smaller airways (bronchioles), which finally end in clusters of tiny air sacs called alveoli.

At each stage of this process, there are mechanisms to protect your lungs from infection. In fact, you're frequently exposed to bacteria and viruses that can cause pneumonia, but your body normally keeps them from entering your lungs and causing a problem. But sometimes — for reasons that aren't always well understood — these microorganisms can get past your body's defenses, finally finding their way into the lungs' air sacs.

There, white blood cells (leukocytes), a key part of your immune system, begin to attack the invading organisms. The accumulating pathogens, white cells and immune proteins cause the air sacs to become inflamed and filled with fluid, leading to the difficult breathing that characterizes many types of pneumonia.

Looking for pneumonia in all the right places
Pneumonia is sometimes classified according to where or how you're exposed to the disease:

• Community-acquired pneumonia. This refers to pneumonia you acquire in the course of your daily life — at school, work or the gym, for instance. Acute eosinophilic pneumonia, a rare and often fatal form of the disease that has developed in soldiers serving in and near Iraq, mimics community-acquired pneumonia. This raises the potential for misdiagnosis and delayed treatment.
• Hospital-acquired (nosocomial) pneumonia. If you're hospitalized, you're at a higher risk of pneumonia, especially if you are on a mechanical ventilator, are in the intensive care unit or have a compromised immune system. This type of pneumonia can be extremely serious, especially for older adults, young children and people with chronic obstructive pulmonary diseases or HIV/AIDS.
• Aspiration pneumonia. This type of pneumonia occurs when foreign matter is inhaled (aspirated) into your lungs — most often when the contents of your stomach enter your lungs after you vomit. This commonly happens when a brain injury or other condition affects your normal gag reflex.
• Pneumonia caused by opportunistic organisms. This type of pneumonia strikes people with compromised immune systems. Organisms that aren't harmful for healthy people can be extremely dangerous for those with AIDS, sickle cell disease and other conditions that impair the immune system. For example, P. carinii pneumonia almost never occurs in otherwise healthy people. Medications that suppress your immune system, such as corticosteroids or chemotherapy also can put you at risk of opportunistic pneumonia.

Adults age 65 or older and very young children, whose immune systems aren't fully developed, are at increased risk of pneumonia. You're also more likely to develop pneumonia if you:

• Have certain diseases. These include immune deficiency diseases such as HIV/AIDS and chronic illnesses such as cardiovascular disease, emphysema or diabetes. You're also at increased risk if you've had your spleen removed, or your immune system has been impaired by chemotherapy or long-term use of immunosuppressant drugs.
• Smoke, or abuse alcohol. Millions of microscopic hairs (cilia) cover the surface of the cells lining your bronchial tubes. The hairs beat in a wave-like fashion to clear your airways of normal secretions, but irritants such as tobacco smoke paralyze the cilia, causing secretions to accumulate. If these secretions contain bacteria, they can develop into pneumonia. Alcohol interferes with your normal gag reflex as well as with the action of the white blood cells that fight infection.
• Are hospitalized in an intensive care unit. Pneumonia is the most common acquired infection among people in hospital intensive care units. People who require mechanical ventilation are particularly at risk because the breathing tube (endotracheal tube) bypasses the normal defenses of the respiratory tract, prevents coughing, and can harbor bacteria and other harmful organisms.
• Are exposed to certain chemicals or pollutants. Your risk of developing some uncommon types of pneumonia increases if you work in agriculture, construction or around certain industrial chemicals or animals. Exposure to air pollution or toxic fumes can also contribute to lung inflammation.
• Live in certain parts of the country. Two types of fungus that occur in the soil in certain parts of the United States can cause lung infections and pneumonia. Coccidioidomycosis, for example, is widespread throughout Southern California and the desert Southwest. The majority of people exposed to the fungus don't get sick, but a few develop severe pneumonia.

  Histoplasmosis is a serious lung infection caused by a soil-borne fungus that's most prevalent in the Ohio and Mississippi River valleys. Infants, young children, older adults and people with chronic lung disease or HIV/AIDS are at increased risk of severe symptoms.

If you think you may have pneumonia, don't hesitate to get medical care. Serious pneumonia can be life-threatening. See your doctor right away if you have a persistent cough, shortness of breath, chest pain that fluctuates with your breathing (pleurisy), an unexplained fever — especially a fever of 102 F or higher for two or more days along with chills and sweats — or if you suddenly feel worse after a cold or the flu.

Be especially prompt about seeking medical care if you're an older adult, or you're affected by alcoholism, injury, chemotherapy or the use of drugs such as prednisone that suppress the immune system. For some older adults and people with heart failure or lung ailments, pneumonia can prove fatal in as little as 24 hours.

If you've received a diagnosis of pneumonia, your doctor will most likely schedule a follow-up visit four to six weeks after your initial diagnosis and treatment. By that time your infection should have cleared, but it's important for your doctor to see you, even if you're feeling better. If you're not feeling better, the follow-up visit is an opportunity for your doctor to schedule tests to determine more specifically what's causing your symptoms.

Your doctor may first suspect pneumonia based on your medical history and a physical exam. During the exam, your doctor will listen to your lungs with a stethoscope to check for abnormal bubbling or cracking sounds (rales) and for rumblings (rhonchi) that signal the presence of thick liquid. Both these sounds may indicate inflammation caused by infection.

You're also likely to have chest X-rays to confirm the presence of pneumonia and to determine the extent and location of the infection. If your immune system is compromised, or the X-rays aren't clear, you may have a more sophisticated imaging test known as a computerized tomography (CT) scan, which takes a series of computer-directed X-rays.

You may also have blood tests to check your white cell count, or to look for the presence of viruses, bacteria or other organisms. Sometimes your doctor may examine a sample of your phlegm or your blood to help identify the microorganism that's causing your illness.

How serious pneumonia is for you depends on your overall health and the type and extent of pneumonia you have. If you're young and healthy, your pneumonia can usually be treated successfully. But if you have heart failure or lung ailments, or if you're older, your pneumonia may be harder to cure. You're also more likely to develop complications, some of which can be life-threatening.

• Bacteria in the bloodstream. Pneumonia can turn deadly when inflammation from the disease fills the air sacs in your lungs and interferes with your ability to breathe. In some cases the infection may invade your bloodstream (bacteremia). It can then spread quickly to other organs.
• Fluid accumulation and infection around the lungs. Sometimes fluid accumulates between the thin, transparent membrane (pleura) covering your lungs and the membrane that lines the inner surface of your chest wall — a condition known as pleural effusion. Normally, the pleurae are silky smooth, allowing your lungs to slide easily along your chest wall when you breathe in and out. But when the pleurae around your lungs become inflamed (pleurisy) — often as a result of pneumonia — fluid can accumulate and may become infected (empyema). In that case, you may have a tube placed between your ribs to drain the fluid or, occasionally, a surgical procedure to clear out some of the infected material.
• Lung abscess. A cavity containing pus (abscess) that forms within the area affected by pneumonia is another potential complication. Abscesses usually are treated with antibiotics, but in rare cases they may need to be removed surgically.

If you have emphysema or pneumonia in both lungs (double pneumonia), you may need a mechanical respirator to help you breathe.

Treatments for pneumonia vary, depending on the severity of your symptoms and the type of pneumonia you have.

• Bacterial. Doctors usually treat bacterial pneumonia with antibiotics. Although you may start to feel better shortly after beginning your medication, be sure to complete your entire course of antibiotics. Stopping medication too soon may cause your pneumonia to return. It also helps create strains of bacteria that are resistant to antibiotics — an increasingly serious problem in the United States.
• Viral. Antibiotics aren't effective against viral forms of pneumonia. And although a few viral pneumonias may be treated with antiviral medications, the recommended treatment is the same as for the flu — rest and plenty of fluids. Overall, it may take you longer to recover from viral pneumonia than from bacterial pneumonia.
• Mycoplasma. Mycoplasma pneumonias are treated with antibiotics. Even so, recovery may not be immediate — it may take four to six weeks for you to recover completely if your pneumonia is serious. In some cases fatigue may continue long after the infection itself has cleared.

In addition to these treatments, your doctor may recommend over-the-counter medications to reduce fever, treat your aches and pains, and soothe the cough associated with pneumonia. You don't want to suppress your cough completely, though, since coughing helps clear your lungs. If you must use a cough suppressant, use the lowest dose that helps you get some rest.

If you have severe pneumonia, you may be hospitalized and treated with intravenous antibiotics or put on oxygen. Still, you may recover as quickly at home with oral antibiotics as in the hospital, especially if you have access to qualified home health care. Sometimes you may spend three or four days in the hospital receiving intravenous antibiotics and then continue to recover at home with oral medication.

You usually don't "catch" pneumonia from someone else. Instead, you develop the disease because your immune system is temporarily weakened, often for no known reason. The following suggestions can help keep you healthy:

• Get vaccinated. Because pneumonia can be a complication of the flu, getting a yearly flu shot is a good way to prevent pneumonia. In addition, get a vaccination against pneumococcal pneumonia at least once after age 65. Your doctor may recommend a pneumonia vaccine if you're younger but have a lung or cardiovascular disease, diabetes or sickle cell anemia, if your immune system is compromised or you've had your spleen removed for any reason. A vaccine known as Prevnar can also help protect young children against pneumonia. It's recommended for all children younger than age 2 and for children 2 years and older who are at particular risk of pneumococcal disease, such as those with an immune system deficiency, cancer, cardiovascular disease or sickle cell anemia. Side effects of the pneumococcal vaccine are generally minor and include mild soreness or swelling at the injection site.
• Wash your hands. Your hands are in almost constant contact with germs that can cause pneumonia. These germs enter your body when you touch your eyes or rub your nose. Washing your hands thoroughly and often can help reduce your risk. When washing isn't possible, use an alcohol-based hand sanitizer, which can be more effective than soap and water in destroying the bacteria and viruses that cause disease. What's more, most hand sanitizers contain ingredients that keep your skin moist.
• Don't smoke. Smoking damages your lungs' natural defenses against respiratory infections.
• Take care of yourself. Proper rest and a diet rich in fruits, vegetables and whole grains along with moderate exercise can help keep your immune system strong.
• Protect others from infection. If you have pneumonia, try to stay away from anyone with a compromised immune system. When that isn't possible, you can help protect others by wearing a face mask and always coughing into a tissue.

If you have pneumonia, the following measures can help you recover more quickly and decrease your risk of complications:

• Get plenty of rest. Even when you start to feel better, be careful not to overdo it.
• Drink lots of fluids, especially water. Liquids keep you from becoming dehydrated and help loosen mucus in your lungs.
• Take the entire course of any prescribed medications. Stopping medication too soon can cause your pneumonia to come back and contributes to the development of antibiotic-resistant bacteria.
• Keep all of your follow-up appointments. Even though you feel better, your lungs may still be infected. It's important to have your doctor monitor your progress.