20. Sir Ronald Ross and malaria
Malaria, like yellow fever, was for centuries viewed as a seasonal illness, the product of pestilential air during the warm and humid months. In addition to smallpox, George Washington suffered from malaria in his youth. Not until Carlos Finlay identified the mosquito as the vector which delivered yellow fever to humans did scientists and researchers eye the same mode of transmission for malaria. Ronald Ross worked at the Presidency General Hospital in Calcutta (Kolkata), applying Finlay’s findings to malaria in India, which occurred at exponential rates annually. Ross proved the life cycle of the malaria virus in mosquitoes, and the transfer of the virus to and from infected birds in 1897.
Ross’s discovery received further support when Walter Reed’s board confirmed the work of Carlos Finlay in 1900. The relationship between mosquitoes and the two greatest of the tropical killing diseases, yellow fever and malaria, offered new means of battling their annual outbreaks. Mosquito abatement through pesticides and the issuance of mosquito-proof clothing and nettings offered protection against the diseases. The first vaccine against yellow fever appeared in 1938. Vaccines against malaria continued to elude researchers into the 21st century. Malaria continued to be treated with quinine, and mosquito abatement efforts continue in areas where malaria is likely to appear in the 21st century.