Scientists predict that rising average temperatures in some regions—a result of climate change—will change the transmission dynamics and geographic range of cholera, malaria, dengue fever, and tick-borne diseases.

Smallpox cannot be found naturally in the wild. Smallpox was officially declared eradicated from the globe in 1980, after an 11-year WHO vaccination campaign—the first human disease to be eliminated as a naturally spread contagion. Today, the virus remains only in laboratory stockpiles.

Smallpox cannot be found naturally in the wild. Smallpox was officially declared eradicated from the globe in 1980, after an 11-year WHO vaccination campaign—the first human disease to be eliminated as a naturally spread contagion. Today, the virus remains only in laboratory stockpiles.

Worldwide, 884 million people do not have access to an adequate water supply, and about three times that number lack basic sanitation services. An estimated 2 million deaths a year can be attributed to unsafe water supplies.

Worldwide, 884 million people do not have access to an adequate water supply, and about three times that number lack basic sanitation services. An estimated 2 million deaths a year can be attributed to unsafe water supplies.

The 1918 influenza pandemic is estimated to have killed between 50 million and 100 million people worldwide. Many of those deaths were due to the effects of pneumococcal pneumonia, a secondary complication of flu for which no antibiotics existed in 1918.

The 1918 influenza pandemic is estimated to have killed between 50 million and 100 million people worldwide. Many of those deaths were due to the effects of pneumococcal pneumonia, a secondary complication of flu for which no antibiotics existed in 1918.

Microbes live in all of these places. They also live in plants and in the air. They can even survive in extreme environments like hot springs, deep ocean thermal vents, and polar ice.

Microbes live in all of these places. They also live in plants and in the air. They can even survive in extreme environments like hot springs, deep ocean thermal vents, and polar ice.

Microbes live in all of these places. They also live in plants and in the air. They can even survive in extreme environments like hot springs, deep ocean thermal vents, and polar ice.

Microbes live in all of these places. They also live in plants and in the air. They can even survive in extreme environments like hot springs, deep ocean thermal vents, and polar ice. 

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

The above describes how vaccines work. Antibiotics work by either killing bacteria or stopping them from reproducing, allowing the body's natural defenses to eliminate the pathogens.

About 36,000 people die from flu-related complications each year in the United States. More than 200,000 are hospitalized.

About 36,000 people die from flu-related complications each year in the United States. More than 200,000 are hospitalized.

Each year about 76 million Americans—or one in four—become infected by what they eat. Approximately 325,000 are hospitalized. More than 5,000 (14 a day) die.

Each year about 76 million Americans—or one in four—become infected by what they eat. Approximately 325,000 are hospitalized. More than 5,000 (14 a day) die.