Tuberculosis: Over 30 million people are expected to die of tuberculosis during this decade. Because of inefficient treatment of the disease in the past, drug-resistant tuberculosis is now a global threat. Some strains are presently immune to drugs that once destroyed the bacteria without fail.

Malaria: This disease afflicts up to 500 million people yearly, killing 2 million. Control has been hindered by lack of or misuse of drugs. As a result, malaria parasites have become resistant to the drugs that once killed them. Complicating the problem is mosquito resistance to insecticides.

Cholera: Cholera kills 120,000 people per year, mostly in Africa, where epidemics have become more widespread and more frequent. Unknown in South America for decades, cholera struck Peru in 1991 and has since spread throughout the continent.

Dengue: This mosquito-borne virus afflicts an estimated 20 million people each year. During 1995 the worst dengue epidemic in Latin America and the Caribbean in 15 years struck at least 14 countries there. Dengue epidemics are increasing because of growing cities, the spread of dengue-carrying mosquitoes, and the mass movement of infected people.

Diphtheria: Mass immunization programs that began 50 years ago made this disease extremely rare in industrialized countries. Since 1990, however, diphtheria epidemics have raged in 15 countries in Eastern Europe and the former Soviet Union. Up to 1 in 4 people who contracted the disease died. During the first half of 1995, about 25,000 cases were reported.

Bubonic plague: During 1995, at least 1,400 cases of human plague were reported to the World Health Organization (WHO). In the United States and elsewhere, the disease has spread to areas that had been plague free for decades.

Source: WHO