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

The National Academies

What You Need To Know About Infectious Disease

An electron micrograph of an influenza virus, showing details of its structure.

Credit: Cynthia Goldsmith/CDC

Viruses

Viruses are tiny, ranging in size from about 20 to 400 nanometers in diameter. Billions can fit on the head of a pin. Some are rod shaped; others are round and 20 sided; and yet others have fanciful forms, with multisided “heads” and cylindrical “tails.”
Viruses are responsible for a wide range of diseases, including the common cold, measles, chicken pox, genital herpes, and influenza.
Viruses are simply packets of nucleic acid, either DNA or RNA, surrounded by a protein shell and sometimes fatty materials called lipids. Outside a living cell, a virus is a dormant particle, lacking the raw materials for reproduction. Only when it enters a host cell does it go into action, hijacking the cell’s metabolic machinery to produce copies of itself that may burst out of infected cells or simply bud off a cell membrane. This lack of self-sufficiency means that viruses cannot be cultured in artificial media for scientific research or vaccine development; they can only be grown in living cells, fertilized eggs, tissue cultures, or bacteria.
 
Viruses are responsible for a wide range of diseases, including the common cold, measles, chicken pox, genital herpes, and influenza. Many of the emerging infectious diseases, such as AIDS and SARS, are caused by viruses.
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What do you know about infectious disease?

Which of the following can be treated with antibiotics?

  • Sorry, that’s incorrect.

    Strep throat is a bacterial infection that can be treated with antibiotics. The common cold and influenza are both viral infections, which do not respond to antibiotics. Antivirals may be prescribed instead.

  • Correct!

    Strep throat is a bacterial infection that can be treated with antibiotics. The common cold and influenza are both viral infections, which do not respond to antibiotics. Antivirals may be prescribed instead.

  • Sorry, that’s incorrect.

    Strep throat is a bacterial infection that can be treated with antibiotics. The common cold and influenza are both viral infections, which do not respond to antibiotics. Antivirals may be prescribed instead.

  • Sorry, that’s incorrect.

    Strep throat is a bacterial infection that can be treated with antibiotics. The common cold and influenza are both viral infections, which do not respond to antibiotics. Antivirals may be prescribed instead.

Infectious Disease Defined

Chronic Inflammation

A prolonged form of localized immune response to harmful agents and damaged tissue that is characterized by redness, swelling, heat, and/or pain.

View our full glossary

National Academies Press

Search the National Academies Press website by selecting one of these related terms.