Ronald Ross was born in India and joined the Indian Medical Service as a military medical officer in 1881. After studying bacteriology in London between 1888 and 1889 he returned to India, and from 1895 - encouraged and guided by Patrick Manson - he pursued a series of investigations into how malaria spreads. On 20 August 1897 he found malaria parasites in the gut of a mosquito that had fed on an infected patient, establishing the mosquito as the vector of the disease. The finding replaced the older 'miasma' theory, which held that malaria arose from bad air, with a vector-based understanding that made control strategies possible for the first time. Ross was awarded the Nobel Prize in Physiology or Medicine in 1902 and remains the first Briton to receive that prize.