The National Academies

The National Academies: What You Need To Know About Infectious Disease

What You Need To Know About Infectious Disease


Pneumonia is an infection of the lungs most often caused by bacteria or viruses present in the environment. Pneumonia can range in seriousness, from mild to life-threatening. Pneumonia is more worrisome in adults ages 65 and older and individuals with compromised immune systems. In addition, the strains of pneumonia acquired in health care settings can be virulent. The bacteria present in these strains tend to become resistant to standard antibiotics quickly, resulting in types of pneumonia that are more difficult to treat.

Typical symptoms of pneumonia include cough, shortness of breath, lower than normal body temperature (in older people), sweating, shaking and the chills, chest pain, headache, muscle pain, and fatigue. Because pneumonia is a serious illness, it is important to go to the doctor if the cough persists, especially if it is accompanied by shortness of breath and the chills. Children under the age of 2 and older adults should contact their doctors immediately, as should those with other medical conditions.

Before pneumonia can be treated, it is important to diagnose the organism that is causing it. If it is a bacterial infection, identifying which bacteria are the culprit will allow doctors to prescribe the appropriate antibiotic. If the illness is caused by a virus, antiviral medication can be used. Aspirin, ibuprofen, or acetaminophen are helpful for reducing the fever, and cough medicine provides some relief from the cough that often accompanies pneumonia. For older adults who are having trouble breathing, admission to the hospital may be warranted.

Because pneumonia may result from a bout of seasonal flu, avoiding that illness by getting the seasonal flu vaccine is a clear preventive measure. Adults ages 65 and older should be vaccinated for Streptococcus pneumoniae, the most common bacteria associated with the disease. Eating properly, following basic sanitation guidelines—such as washing your hands frequently, getting enough sleep, exercising, and not smoking—also goes a long way toward keeping people healthy.


Explore Other Topics

What do you know about infectious disease?

True or False: Our bodies contain at least 10 times more human cells than bacterial cells.

  • Sorry, that’s incorrect.

    Our bodies contain at least 10 times more bacterial cells than human cells. 

  • Correct!

    Our bodies contain at least 10 times more bacterial cells than human cells. 

Infectious Disease Defined


A ring of DNA usually found in bacteria that is separate from and can replicate independently from DNA in a chromosome and can provide bacteria with some advantages, such as antibiotic resistance.

View our full glossary