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

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 grown in artificial media for scientific research or vaccine development; they can be grown only in living cells, fertilized eggstissue cultures, or bacteria.
 
Viruses are responsible for a wide range of diseases, including the common cold, measleschicken pox, genital herpes, and influenza. They also cause many of the emerging infectious diseases, among them AIDS, Ebola, and Zika.
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Disease Watchlist

What do you know about infectious disease?

Which of the following is a bacterial infection?

  • Sorry, that’s incorrect.

    Strep throat is a bacterial infection. Hookworm is caused by a parasite and chickenpox and influenza are both caused by viruses.

  • Sorry, that’s incorrect.

    Strep throat is a bacterial infection. Hookworm is caused by a parasite and chickenpox and influenza are both caused by viruses.

  • Correct!

    Strep throat is a bacterial infection. Hookworm is caused by a parasite and chickenpox and influenza are both caused by viruses.

  • Sorry, that’s incorrect.

    Strep throat is a bacterial infection. Hookworm is caused by a parasite and chickenpox and influenza are both caused by viruses.

Infectious Disease Defined

Metabolism
The sum total of chemical reactions that occur within a living cell both to build new molecules within the cell and break down and assimilate sources of energy for the cell.

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National Academies Press

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