Ross, Ronald (1857–1932)

The life cycle of the malaria parasite is split between mosquito and human hosts. The parasites are injected into the human bloodstream by an infected Anopheles mosquito and carried to the liver. Here they attack red blood cells, and multiply asexually. The infected blood cells burst, producing spores, or merozoites, which reinfect the bloodstream. After several generations, the parasite develops into a sexual form. If the human host is bitten at this stage, the sexual form of the parasite is sucked into the mosquito's stomach. Here fertilization takes place, the zygotes formed reproduce asexually and migrate to the salivary glands ready to be injected into another human host, completing the cycle.

Indian-born British physician and bacteriologist who was awarded a Nobel Prize for Physiology or Medicine in 1902 for his work on the role of the Anopheles mosquito in transmitting malaria. From 1881 to 1899 he served in the Indian Medical Service, and during 1895–98 identified mosquitoes of the genus Anopheles as being responsible for the spread of malaria. He was knighted in 1911.

Ross studied at St Bartholomew's Hospital in London. On retiring from the Indian Medical Service in 1899, he returned to Britain, eventually becoming professor of tropical medicine at Liverpool. During World War I he was consultant on malaria to the War Office, and when the Ross Institute of Tropical Diseases was opened in 1926, he became its first director.

While on leave in England in 1894, Ross became acquainted with Scottish physician Patrick Manson, who suggested that malaria was spread by a mosquito. Returning to India, Ross collected mosquitoes, identifying the various species and dissecting their internal organs. In 1897 he discovered in an Anopheles mosquito a cyst containing the parasites that had been found in the blood of malarial patients.

Later, using caged birds with bird malaria, Ross was able to study the entire life history of the parasite inside a mosquito, and the mode of transmission to the victim.