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?

 

Of the more than 1,700 known viruses, bacteria, and other pathogens that infect people, how many have come from animals?

 

 

 

  • Sorry, that’s incorrect.

    More than half of the known pathogens that infect people have come from animals. Of the 37 new infectious diseases identified in just the past 30 years, two-thirds sprang from animals.

  • Sorry, that’s incorrect.

    More than half of the known pathogens that infect people have come from animals. Of the 37 new infectious diseases identified in just the past 30 years, two-thirds sprang from animals.

  • Correct!

    More than half of the known pathogens that infect people have come from animals. Of the 37 new infectious diseases identified in just the past 30 years, two-thirds sprang from animals.

Infectious Disease Defined

Fertilized Egg

Sometimes referred to as a zygote, this is the resulting initial cell formed when a sperm cell unites with an egg cell.

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National Academies Press

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