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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Disease Watchlist

What do you know about infectious disease?

Due in large measure to the toll of infectious diseases, the gap in life expectancy between the richest and poorest countries now exceeds how many years?

  • Sorry, that’s incorrect.

    The gap in life expectancy between the richest and poorest countries now exceeds 40 years.

  • Sorry, that’s incorrect.

    The gap in life expectancy between the richest and poorest countries now exceeds 40 years.

  • Correct!

    The gap in life expectancy between the richest and poorest countries now exceeds 40 years.

  • Sorry, that’s incorrect.

    The gap in life expectancy between the richest and poorest countries now exceeds 40 years.

Infectious Disease Defined

Latent Infection

A type of persistent viral infection in which the virus is not currently producing additional viral offspring, but could later be reactivated and begin producing copies of the virus without the host being re-infected.

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National Academies Press

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