Magazine article Population Bulletin

Controlling Infectious Diseases

Magazine article Population Bulletin

Controlling Infectious Diseases

Article excerpt

The 20th century was a triumph for human health and longevity. An Indian born in 1900 had a life expectancy of 22 years; an American baby born that year could expect to live about 49 years. By century's end life expectancy had soared to unprecedented levels even in many poor countries. In 2005, average life expectancy at birth in the United States was 78 years; in India it was 62 years.1

The falling death toll from infectious diseases-primarily among infants and young children-led to these spectacular improvements in human life expectancy. For most of human history, communicable diseases such as malaria, smallpox, and tuberculosis (TB) were leading causes of death. TB was the second-highest cause of death in the United States in 1900, and malaria was a major problem in southeastern U.S. states. These diseases were effectively controlled in the United States and declined throughout much of the world in the 20th century. One major disease-smallpox-was virtually wiped out; another-polio-may be close to eradication.2

Improvements in sanitation and the development of vaccines and antibiotics accelerated the decline of infectious and parasitic diseases (IPDs) in the 20th century.

But, with a few exceptions, communicable diseases have not been vanquished. The microbes that cause these diseases continue to evolve, sometimes requiring new drugs and methods to combat them. New pathogens emerge, or make the jump from infecting animals to infecting humans. The most recent global estimates show that communicable diseases cause about one-third of all deaths (see Figure 1). Pneumonia and other lower respiratory diseases are the largest group, followed by HIV/AIDS, diarrheal diseases, TB, and malaria.

Communicable diseases impose vastly different health burdens on the wealthy and poor. They are the primary reason why a baby born in Somalia today is 30 times more likely to the in infancy than a baby born in France.3 Most of these diseases-including measles, HIV, TB, and malaria-are preventable and treatable using proven and often surprisingly low-cost health interventions. But control of communicable diseases will require additional financial investments, fundamental improvements in health delivery, and longer-term political commitments.4 International and national organizations such as the U.S. Agency for International Development (USAID), the World Health Organization (WHO), the World Bank, and UNICEF-aided by private funders such as the Bill & Melinda Gates Foundation-have spearheaded major efforts to attack infectious diseases.

Large-scale vaccination campaigns, for example, save millions of lives from measles and whooping cough each year. Other diseases-such as malaria-have proved more difficult to control. Although greatly diminished worldwide, malaria has resurged in many countries and continues to be a leading cause of childhood deaths in Africa and a drag on health in several other regions. Likewise, TB, which lost its hold on Europe and the United States by the mid-20th century, continues to devastate the health of millions in developing countries-especially where HIV/AIDS is prevalent. TB is re-emerging in many Eastern European countries where HIV is rapidly increasing.

Some of the miracle drugs that suppressed major diseases have lost their magic as viruses and parasites develop resistance to them. The mosquitoes that transmit malaria, dengue fever, and other diseases have become immune to some common insecticides. The parasites carried by mosquitoes have developed a resistance to drugs formerly used to treat them. Medical researchers are in a race to develop new weapons against diseasecarrying pests, viruses, and parasites before the current arsenal is obsolete.

In the late-20th century, the world was also hit with a new pandemic-HIV-that infects more than 40 million people today and causes at least 3 million deaths annually. HIV undermines the immune system-causing AIDS and making it harder for HIV-infected individuals to fight other diseases. …

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