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

The National Academies

What You Need To Know About Infectious Disease

How Infection Works

Encountering Microbes

Microbes have inhabited the earth for billions of years and may be the earliest life forms on the planet. They live in every conceivable ecological niche—soil, water, air, plants, rocks, and animals. They even live in extreme environments, such as hot springs, deep ocean thermal vents, and Antarctic ice. Indeed microbes, by sheer mass, are the earth’s most abundant life form and are highly adaptable to external forces. How does our modern lifestyle bring us into greater contact with infectious agents—the “bad” microbes? And when we encounter them, how do they get into our bodies?

New Meeting Places

Almost 2 million passengers, each a potential carrier of infection, travel daily by aircraft to international destinations.

International trade, expanded development into forest areas, and worldwide travel are just a few of the reasons people are increasingly coming into contact with infectious agents. Learn more about these new encounters.

More about new meeting places

Entering the Human Host

The most common vector for human infection is the mosquito, which transmits malaria, West Nile virus, and yellow fever.

What do sneezes, ticks, and raw meat have in common? They are all vehicles for pathogens (aka disease-causing microbes) to infect humans. Learn more about how infectious microbes spread.

More about entering the human host

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Infectious Disease Videos

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Disease Watchlist

What do you know about infectious disease?

In 2008, about how many people worldwide were infected with HIV (human immunodeficiency virus)?

  • Sorry, that’s incorrect.

    In 2008, more than 33 million people worldwide were infected with HIV (human immunodeficiency virus). In that same year, an estimated 2 million people died from AIDS (acquired immunodeficiency syndrome), the final stage of HIV infection.

  • Sorry, that’s incorrect.

    In 2008, more than 33 million people worldwide were infected with HIV (human immunodeficiency virus). In that same year, an estimated 2 million people died from AIDS (acquired immunodeficiency syndrome), the final stage of HIV infection.

  • Correct!

    In 2008, more than 33 million people worldwide were infected with HIV (human immunodeficiency virus). In that same year, an estimated 2 million people died from AIDS (acquired immunodeficiency syndrome), the final stage of HIV infection.

Infectious Disease Defined

Cirrhosis

A condition caused by chronic liver disease characterized by the development of scar tissue leading to a loss of liver function.

View our full glossary

National Academies Press

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