The National Academies

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

What You Need To Know About Infectious Disease

Global Challenges

National borders do not block the advance of infectious diseases. Learn how our modern way of life contributes to the spread and emergence of disease.



More than 3 million airline passengers cross international borders daily.

The rapid movement of people and goods around the world significantly impacts the spread of infectious disease. So do population shifts from the countryside to crowded cities. Discover how our modern way of life is contributing to greater exposure to pathogens.

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Climate Change

Climate Change

A number of diseases are highly sensitive to changes in the environment.

Rising average temperatures, changes in precipitation patterns, and other effects attributed to climate change are expected to influence the spread of infectious disease. Find out more about the connection between climate and disease.

More about climate change

Ecosystem Disturbances

Ecosystem Disturbances

The clearing and settlement of tropical rainforests exposes woodcutters, farmers, and ecotourists to new vector-borne diseases.

When people move into new environments and are exposed to microbes they may not have encountered before, it can lead to the spread of disease. Changing an ecosystem by clear-cutting a forest or letting farmland revert back to meadows also has an impact. Find out how.

More about ecosystem disturbances

Poverty, Migration & War

Poverty, Migration & War

Pneumonia, diarrhea, and malaria are among the leading causes of death in the developing world in children under the age of 5.

Many living in poverty do not have access to clean water, proper sanitation, or much-needed medicines. Disruptions caused by migration, extreme weather events, and war lead to similar health challenges and add more. Learn how these circumstances make populations vulnerable to disease. 

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The U.S. Department of Homeland Security identified smallpox, anthrax, Ebola, and plague as potential bioweapons of the greatest concern.

Deadly pathogens are highly accessible. With the exception of smallpox, they all occur naturally in the wild. Learn more about why, in some ways, biological agents are the perfect weapons of terror.

More about bioterrorism

Explore Other Topics

What do you know about infectious disease?

True or False: Our bodies contain at least 10 times more human cells than bacterial cells.

  • Sorry, that’s incorrect.

    Our bodies contain at least 10 times more bacterial cells than human cells. 

  • Correct!

    Our bodies contain at least 10 times more bacterial cells than human cells. 

Infectious Disease Defined


A unit of length equal to one one-billionth (1 x 10-9) of a meter.

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