About one quarter of all deaths worldwide are caused by infectious disease. More than two-thirds of the deaths in children under the age of five are caused by infectious disease.

About one quarter of all deaths worldwide are caused by infectious disease. More than two-thirds of the deaths in children under the age of five are caused by infectious disease.

The expanded use of cell phones does not have an impact on the spread of infectious disease. Climate change, ecosystem disturbances, war, poverty, migration, and global trade all contribute to the spread of infectious disease.

The expanded use of cell phones does not have an impact on the spread of infectious disease. Climate change, ecosystem disturbances, war, poverty, migration, and global trade all contribute to the spread of infectious disease.

The expanded use of cell phones does not have an impact on the spread of infectious disease. Climate change, ecosystem disturbances, war, poverty, migration, and global trade all contribute to the spread of infectious disease.

Tuberculosis is caused by a bacterial infection. Chicken pox, the common cold, and influenza are all caused by viral infections.

Tuberculosis is caused by a bacterial infection. Chicken pox, the common cold, and influenza are all caused by viral infections.

Tuberculosis is caused by a bacterial infection. Chicken pox, the common cold, and influenza are all caused by viral infections.

Someone in the world is newly infected with tuberculosis (TB) every second. In 2008 there were an estimated 9.4 million new cases of tuberculosis and 1.8 million deaths.The vast majority of TB deaths are in the developing world, and more than half of all deaths occur in Asia.

Someone in the world is newly infected with tuberculosis (TB) every second. In 2008 there were an estimated 9.4 million new cases of tuberculosis and 1.8 million deaths.The vast majority of TB deaths are in the developing world, and more than half of all deaths occur in Asia.

Most infectious diseases are impacted by changes in the environment. Malaria, dengue, and viral encephalitis infections, for example, are highly sensitive to environmental changes.

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.

Influenza is not a vector-borne disease, meaning it is not transmitted to humans indirectly via an insect, an arthropod, or another animal. Malaria and yellow fever are transmitted by mosquitoes. Lyme disease is transmitted by deer ticks.

Influenza is not a vector-borne disease, meaning it is not transmitted to humans indirectly via an insect, an arthropod, or another animal. Malaria and yellow fever are transmitted by mosquitoes. Lyme disease is transmitted by deer ticks.

Influenza is not a vector-borne disease, meaning it is not transmitted to humans indirectly via an insect, an arthropod, or another animal. Malaria and yellow fever are transmitted by mosquitoes. Lyme disease is transmitted by deer ticks.

White blood cells are not a type of infectious agent. Part of the immune system, white blood cells fight infection rather than cause it. 

White blood cells are not a type of infectious agent. Part of the immune system, white blood cells fight infection rather than cause it. 

White blood cells are not a type of infectious agent. Part of the immune system, white blood cells fight infection rather than cause it. 

Antibiotics only work on bacterial infections, not viral infections such as influenza and the common cold. In fact, inappropriate use and overuse of antibiotics contributes to the emergence of drug-resistant bacteria.