In ancient times people believed that evil spirits were the main cause of diseases. They approached witch doctors and magicians for treatment. Gradually, the detailed study about the functioning of the body helped the people to learn about the causes of diseases. New medicines were developed. The discovery of quinine helped in the treatment of malaria. Influenza, which caused many deaths, can now be controlled by eucalyptus.
The wonder drug penicillin, discovered by Alexander Fleming in 1928, helps to prevent the growth of bacteria in the body. The discovery of antibiotics helped to bring relief from infection. Today we have a variety of medicines to control the killer diseases like smallpox, tuberculosis, malaria, influenza, cholera and plague.