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 mosquito is the vector for West Nile virus. The mosquito suffers no ill effects from the virus but transmits it to humans and other warm-blooded creatures (such as crows) when it takes a blood meal. 

The mosquito is the vector for West Nile virus. The mosquito suffers no ill effects from the virus but transmits it to humans and other warm-blooded creatures (such as crows) when it takes a blood meal. 

The mosquito is the vector for West Nile virus. The mosquito suffers no ill effects from the virus but transmits it to humans and other warm-blooded creatures (such as crows) when it takes a blood meal. 

The use of thimerosal has been an object of controversy, with some arguing that the substance caused autism in children. However, extensive independent research has presented no convincing evidence of harm associated with the low levels of thimerosal previously present in vaccines.

Washing with regular soap is considered the most important way to prevent disease transmission. Routine consumer use of residue-producing antibacterial products has no added benefit and may actually contribute to antibiotic resistance.

All of the above can help prevent infectious disease. Other behaviors, such as exercising caution around wild and unfamiliar domestic animals, avoiding insect bites, practicing safe sex, and being vigilant about disease threats while traveling abroad, can also reduce the risk of infection.

All of the above can help prevent infectious disease. Other behaviors, such as exercising caution around wild and unfamiliar domestic animals, avoiding insect bites, practicing safe sex, and being vigilant about disease threats while traveling abroad, can also reduce the risk of infection.

All of the above can help prevent infectious disease. Other behaviors, such as exercising caution around wild and unfamiliar domestic animals, avoiding insect bites, practicing safe sex, and being vigilant about disease threats while traveling abroad, can also reduce the risk of infection.

Lower respiratory tract infections (including pneumonia) kill more children worldwide than any other infectious disease. Together these diseases are the five leading causes of infectious disease worldwide, accounting for nearly one-fifth of all deaths.

Lower respiratory tract infections (including pneumonia) kill more children worldwide than any other infectious disease. Together these diseases are the five leading causes of infectious disease worldwide, accounting for nearly one-fifth of all deaths.

Lower respiratory tract infections (including pneumonia) kill more children worldwide than any other infectious disease. Together these diseases are the five leading causes of infectious disease worldwide, accounting for nearly one-fifth of all deaths.

Lower respiratory tract infections (including pneumonia) kill more children worldwide than any other infectious disease. Together these diseases are the five leading causes of infectious disease worldwide, accounting for nearly one-fifth of all deaths.

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.

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

Infection occurs when viruses, bacteria, or other microbes enter your body and begin to multiply. Disease follows when the cells in your body are damaged as a result of infection, and signs and symptoms of an illness appear.