Other diseases, such as diptheria?, [typhoid fever]?, tuberculosis and [whooping cough]? were greatly reduced throughout the world due to childhood immunisation? programs, improved sanitation?, and the use of antibiotics. Malaria, even though easily treatable, is still a major killer in poor countries.
In the United States the death rate from pneumonia? and influenza? fell 93% in the 20th century; bronchitis? was once responsible for 3% of deaths in America - that figure has fallen to nearly one-tenth of 1%.
Two major pandemics occured in the 20th century: an outbreak of influenza which killed about 25 million people in 1918, and the appearance of AIDS in the 1980s. AIDS is transmitted by a virus, and viral diseases can usually only be overcome by vaccination. An effective AIDS vaccine has eluded researchers so far. Anti-viral drugs have been developed, but they are too expensive for most people suffering from AIDS.
A concern is the appearance of antibiotic-resistant strains of infectious organisms. It is believed that the overuse of antibiotics, including their use in animal husbandry, contributes to this development.