All of the above are urgently needed in developing nations. A major barrier to achieving these improvements is the underlying weakness of health systems in resource-poor countries, including a shortage of health workers and a lack of disease surveillance programs.

All of the above are urgently needed in developing nations. A major barrier to achieving these improvements is the underlying weakness of health systems in resource-poor countries, including a shortage of health workers and a lack of disease surveillance programs.

All of the above are urgently needed in developing nations. A major barrier to achieving these improvements is the underlying weakness of health systems in resource-poor countries, including a shortage of health workers and a lack of disease surveillance programs.

The human papillomavirus (HPV) causes more than 90% of cervical cancer cases.

The human papillomavirus (HPV) causes more than 90% of cervical cancer cases.

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.

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.

Trichinosis is not a viral disease. It is caused by a helminth (parasitic worm) found in undercooked meat, not by a virus. 

Trichinosis is not a viral disease. It is caused by a helminth (parasitic worm) found in undercooked meat, not by a virus.   

Scientists believe that hot weather may speed up both the breeding cycle of mosquitoes and replication of the virus in insects’ guts.

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.

Although there are treatments available in the form of antivirals, we still currently lack a vaccine for HIV.

Although there are treatments available in the form of antivirals, we still currently lack a vaccine for HIV.

Although there are treatments available in the form of antivirals, we still currently lack a vaccine for HIV.

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.

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.