The Greek physician Hippocrates described the symptoms of pneumonia 2,400 years ago. But this affliction of the lungs still kills more people in the United States than any other infectious disease, taking 40,000 to 70,000 lives each year. It is the most common lethal nosocomial, or hospital-acquired, infection.
The term "pneumonia" describes a group of symptoms that may be caused by bacteria, viruses, parasites, or fungi. Pneumonia is a severe inflammation of the lungs in which the thin tissue around air spaces called alveoli swells and fills with fluid. Symptoms include shaking, chills, a rapidly rising fever, and sharp chest pain made worse by breathing and coughing. Pneumonia is a common cause of death among elderly people and young children whose immune systems are weakened or impaired in some way.
A common bacterium, Streptococcus pneumoniae, lives in the respiratory tract of 15 percent of the population without causing problems. It can spread pneumonia only if inhaled deeply into the lungs. The germ travels via droplets conveyed through coughing, sneezing, and even talking in close proximity. Bacterial pneumonia is most common in winter and spring, when upper respiratory tract infections are frequent. Pneumonia is also a common complication of influenza.
Most cases of bacterial pneumonia can be effectively treated with penicillin. Between 1936 and 1945, pneumonia death rates in the United States dropped approximately 40 percent with the greater availability of antibiotics. The more common viral pneumonia usually diminishes on its own, but all strains of pneumonia can be serious if neglected, and people should always seek medical supervision for their care.
Along with other acute respiratory infections, pneumonia is in a near tie with diarrheal diseases as a leading cause of death in children under 5 worldwide. It's estimated that pneumonia kills approximately two million children each year, with 40 percent of these deaths in Africa. More than two-thirds of pneumonia deaths among children in the developing world are caused by just two kinds of bacteria: Pneumoccoccus and Hemophilus influenzae.
Trained community health workers can dramatically reduce these deaths when they teach parents to identify the early signs of pneumonia: rapid breathing and violent shaking in the chest. At present, as many as two-thirds of children with acute respiratory infections are not treated by trained health providers. Even the simplest understanding of how to count the number of breaths a child takes per minute can help community health workers and parents recognize pneumonia and administer antibiotics if appropriate, or seek help at a clinic or hospital.
Time is often of the essence with pneumonia: Severe pneumonia can kill victims within hours as they literally drown in the fluids flooding their lungs. In Honduras, pneumonia treatment is part of a national, integrated community child care program that trains community volunteers to monitor children's growth, provide health education, and treat pneumonia and diarrhea.
A major contributing factor to respiratory infections is indoor air pollution. We tend to think of this type of air pollution as a problem in the industrialized world, but half of the world's people rely on dung, wood, crop waste, or coal for cooking and heating. These solid fuels cause high levels of particulate matter in the developing world that are 100 times higher than concentrations in the United States or Europe. Poor ventilation of smoke makes breathing difficult and exposes young children to severe respiratory infections. Reducing indoor air pollution may require switching to cleaner and more efficient fuels such as liquid petroleum, electricity, or solar power, and the cooperation of governments. Pneumonia is also a leading cause of immediate death among AIDS patients.
Vaccines against certain kinds of pneumonia exist for adults, but many high-risk patients do not routinely receive them. A relatively new pneumococcal vaccine for children called Prevnar, introduced by Wyeth Pharmaceuticals, has proved effective in the United States, dramatically reducing disease incidence by approximately 80 percent. But the $50-per-dose U.S. price makes it far too expensive to be widely used in the developing world. Another H Flu (Hib) vaccine has also been found to be effective in field testing. International health economists are searching for a better way to fund lifesaving vaccines than relying on the free market alone.