Multiple: Pneumonia

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Multiple: Pneumonia

Causes and Symptoms
The Future
For more information


Pneumonia is a serious inflammatory lung disorder in which the alveoli—tiny air-filled sacs in the lungs that ordinarily absorb oxygen from the air—fill with fluid or pus. As a result of this inflammation, the person cannot get enough oxygen into the bloodstream to meet the needs of body tissues. In addition, the disease organisms responsible for most cases of pneumonia can spread from the lungs into the bloodstream and infect other vital organs, thus causing the person's death.

Pneumonia has at least thirty different causes. Although most cases of pneumonia are caused by bacteria, viruses, or other disease organisms, the illness can also be the result of non-infectious causes such as chemical injuries to the lungs, food or saliva accidentally getting into the airway, or even by allergies to substances in the air.

Pneumonia is sometimes classified by the ways in which people can acquire it. Some common types of pneumonia include:

  • Nosocomial pneumonia: Nosocomial refers to infections acquired by hospital patients. This type of pneumonia can be very serious, partly because hospitalized people are already ill or weak from surgery, and partly because the bacteria found in hospitals are often more resistant to antibiotics.
  • Ventilator-associated pneumonia: Patients who must be placed on a ventilator to help them breathe are at increased risk of developing pneumonia.
  • Community-acquired pneumonia (CAP): CAP refers to pneumonia caused by disease organisms in people who have not been recently hospitalized.
  • Aspiration pneumonia: Aspiration is the medical term for getting saliva, food particles, or liquids into the airway and lungs. Aspiration pneumonia is common in the elderly, patients with Parkinson disease, and others who may have trouble swallowing normally. The materials that get into the lungs can cause pneumonia either by chemical irritation or by carrying bacteria that cause inflammation.
  • Opportunistic pneumonia: Opportunistic infections are caused in people with weakened immune systems by organisms that do not ordinarily cause disease in people with healthy immune systems. People with AIDS are vulnerable to a particular type of pneumonia called PCP, which stands for Pneumocystis carinii pneumonia. Pneumocystis is classified as a fungus.
  • Chemical pneumonia. Breathing in certain chemicals, particularly pesticides, can cause pneumonia.
  • Walking pneumonia: Walking pneumonia is an older term for pneumonia that does not make patients sick enough to stay in bed; that is, they are well enough to go about their ordinary activities in spite of coughing and headaches. Most cases of walking pneumonia are caused by mycoplasmas, a kind of bacteria, or by viruses.
  • Emerging diseases. Some emerging diseases, such as severe acute respiratory syndrome (SARS) and avian influenza (bird flu) can cause pneumonia in otherwise healthy people.

An Ancient Killer

Pneumonia has caused the death of many famous people, not just those who lived before the discovery of antibiotics, but also some who died in the late twentieth or early twenty-first century:

  • William Henry Harrison (1773–1841), ninth president of the United States. Died one month after catching a cold at his inauguration.
  • Stonewall Jackson (1824–1863), Confederate general during the Civil War. Died after being wounded at the battle of Chancellorsville.
  • Franz Liszt (1811–1886), composer. Died of pneumonia caught while attending a music festival.
  • Leo Tolstoy (1828–1910), novelist. Died of pneumonia at a railway station following exposure to cold.
  • Harriet Tubman (c. 1820–1913), former slave and leader of the Underground Railroad. Died of pneumonia following several years of declining health.
  • Bert Lahr (1895–1967), actor who played the Cowardly Lion in The Wizard of Oz. Died of pneumonia while making another film.
  • Jim Henson (1936–1990), puppeteer best known for the Muppets movies and

    television show. Died of multiple organ failure following bacterial pneumonia.
  • Luciano Pavarotti (1935–2007), opera singer. Died of pneumonia as a complication of treatment for pancreatic cancer.


Pneumonia is one of the oldest diseases known to humans, first described by Hippocrates in the fifth century BCE. Pneumonia can vary from a mild infection of the lungs that does not require hospital treatment to

a fatal illness. In the 1930s pneumonia was the leading cause of death in the United States. It is still the eighth most common cause, killing 60,000 people each year. Pneumonia can come on either suddenly or gradually. Its major symptoms include chest pain, fever, severe coughing, and greenish or pus-colored sputum (mucus or phlegm). The early stages of pneumonia are sometimes mistaken for a cold or flu. The severity of the symptoms depends on the organism causing the illness and the person's basic level of health.

Bacterial pneumonia often comes on suddenly with sweating, severe chest pain, high fever (up to 105°F/40.6°C), chills, and a cough that produces greenish or yellowish sputum. It can develop by itself or following a viral infection like a cold or the flu.

Viral pneumonia accounts for about half of all cases. Some cases are mild. In other cases, people have symptoms resembling those of influenza: fever, aching muscles, headache, and weakness. Within twelve to thirty-six hours, however, patients become much sicker, may start gasping for breath, and their cough becomes worse. Patients with viral pneumonia sometimes develop a secondary bacterial pneumonia.

Pneumonia caused by mycoplasma is usually mild and develops gradually. It is common among children and young adults because it spreads rapidly in day care, college dormitories, and other group settings. The most noticeable symptoms of mycoplasmal pneumonia are a dry cough and whitish sputum. Some patients also experience nausea and vomiting.


Pneumonia is a widespread health problem in the general population as well as hospital inpatients and those in nursing homes. According to the Centers for Disease Control and Prevention (CDC), 1.4 million people in the United States are treated in hospitals each year for pneumonia, with an average stay of five days. About 2 percent of nursing home residents are treated for pneumonia in an average year.

Pneumonia is most common in the winter months in the United States. It affects males more often than females, and African Americans more often than members of other racial or ethnic groups.

In developing countries, pneumonia is a common cause of death among children. The World Health Organization (WHO) estimates that 2 million children die each year around the world, and that one in three deaths among newborn babies results from pneumonia.

People who are at increased risk of pneumonia include:

  • Those with weakened immune systems, including people who are HIV-positive, have received organ transplants, or are being treated for cancer with chemotherapy
  • People with emphysema, cystic fibrosis, or other diseases that affect the lungs
  • People who smoke or abuse alcohol
  • People who are hospitalized or in nursing homes, particularly those placed on artificial respirators
  • People whose jobs expose them to pesticides, large amounts of dust, or other chemicals that irritate the lungs
  • Very young children and adults over age sixty-five
  • People with diabetes, kidney disorders, sickle cell anemia, or heart disease

Causes and Symptoms

The causes, types, and major symptoms of pneumonia have been described in previous sections.

Other symptoms that some people with pneumonia experience include:

  • Rapid but shallow breathing
  • Loss of appetite
  • Mental confusion and disorientation (more common in the elderly)
  • Unusual tiredness
  • Heavy sweating and clammy skin


The diagnosis of pneumonia is made by a combination of the patient's history, a physical examination, and appropriate laboratory and imaging tests. The doctor will need to know when the symptoms started, whether the patient has been recently hospitalized, whether he or she has had a cold or flu, and similar questions. The physical examination will include listening to the patient's breathing through a stethoscope as well as taking the temperature and pulse. Patients with pneumonia typically have abnormal rubbing, crackling, or other harsh sounds that the doctor can hear. In addition, the number of breaths per minute is usually high.

A chest x ray will usually be ordered. Other tests include:

  • A complete blood count (CBC). An unusually high number of white blood cells is a common sign of an infection.
  • A sputum test. The doctor can collect a sample of the patient's sputum and send it to a laboratory to identify the organisms that may be causing the infection. Not everyone with pneumonia will produce sputum and not everyone who produces sputum has pneumonia.


Treatment depends on the cause of the pneumonia. Pneumonia caused by bacteria or mycoplasma is treated with a seven- to ten-day course of antibiotics. Viral infections cannot be treated by antibiotics; in some cases, the doctor may prescribe antiviral medications like rimantadine, which is used to treat some types of influenza. Most patients can care for themselves at home by taking the prescribed medication and by getting plenty of rest, drinking fluids, and taking over-the-counter pain relievers to reduce fever and headaches. It is important for people recovering at home not to return to work or a normal schedule of activities too quickly, as the pneumonia can recur. Recurrences can be more severe than the initial infection.

People who are severely ill and having difficulty breathing are hospitalized, given higher levels of oxygen to breathe, and given intravenous antibiotics. They will be given a follow-up x ray by the doctor after they are well enough to leave the hospital.


The prognosis for pneumonia depends on the organism or irritant causing it, the patient's age and general health, and the time elapsed before diagnosis and treatment. Young people who are diagnosed and treated early may recover in about ten days. Middle-aged adults may take several weeks to recover fully. Mycoplasmal pneumonia takes somewhat longer than either bacterial or viral pneumonia to go away—sometimes as long as six weeks.

The prognosis for recovery is poor for people who develop ventilator-associated pneumonia (about 50 percent will die) or those with bacterial pneumonia that spreads into the bloodstream (about 20 percent will die). Doctors sometimes use a rule called the pneumonia severity index or PSI to estimate a specific patient's chances of recovery. The PSI is based on age, gender, vital signs, and laboratory test results.


An important measure that anyone can take to lower the risk of pneumonia is to quit smoking (or not start in the first place). Another step is vaccination. There is a specific vaccine called Pneumovax that protects against a specific bacterium called the pneumococcus, a common cause of bacterial pneumonia. Pneumovax is recommended for children under two and older children with sickle cell anemia, diabetes, or other diseases that affect the immune system, as well as for adults over fifty-five. A different version of this vaccine, called Prevnar, is now given to children. Older adults should also receive yearly flu shots, as bacterial pneumonia is a common complication of influenza.

The Future

Pneumonia is likely to continue to be a common health problem, especially since it has so many different causes. On the one hand, the development of effective vaccines against flu viruses and the pneumococcus has had some positive effects in reducing the number of cases among children and older adults in the United States. On the other hand, the development of drug-resistant bacteria and the emergence of such new diseases as severe acute respiratory syndrome (SARS) present new challenges to doctors and public health officials.

SEE ALSO AIDS; Avian influenza; Common cold; Emphysema; Influenza; Parkinson disease; Severe acute respiratory syndrome


Alveoli (singular, alveolus): Tiny air sacs in the lungs where carbon dioxide in the blood is exchanged for oxygen from the air.

Aspiration: The entry of food, liquids, or other foreign substances into the lungs during the breathing process.

Community-acquired: Referring to a disease that a person gets in the course of ordinary activities rather than in a hospital or clinic.

Mycoplasma: A very small bacterium that causes a mild but long-lasting form of pneumonia.

Nosocomial: Referring to a disease that a person gets while hospitalized.

Opportunistic infection: An infection that occurs only in people with weakened immune systems.

Sputum: Mucus and other matter that is coughed or brought up from the lungs or throat.

For more information


Judd, Sandra J., ed. Respiratory Disorders Sourcebook, 2nd ed. Detroit, MI: Omnigraphics, 2008.

Silverstein, Alvin, Virginia Silverstein, and Laura Silverstein Nunn. The Flu and Pneumonia Update. Berkeley Heights, NJ: Enslow Elementary, 2006.


American Lung Association. Pneumonia. Available online at{71CC3CFD-4B3E-49C8-AA88-D76EAE1FB9F5}&notoc=1 (updated June 2007; accessed August 20, 2008).

Centers for Disease Control and Prevention (CDC). Pneumococcal Conjugate Vaccine: What You Need to Know. Available in PDF format at (issued September 30, 2002; accessed August 20, 2008).

KidsHealth. Pneumonia. Available online at (updated June 2005; accessed August 20, 2008).

Mayo Clinic. Pneumonia. Available online at (updated May 10, 2007; accessed August 20, 2008).

National Institute of Allergy and Infectious Diseases (NIAID). Pneumococcal Pneumonia. Available online at (updated July 11, 2006; accessed August 20, 2008).

National Library of Medicine (NLM). Pneumonia. Available online at (accessed August 20, 2008). This is an online tutorial with voiceover. Viewers have the option of a self-playing version, a text version, or an interactive version with questions.

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