Research on malaria
The parasite responsible for malaria was identified at the end of the 19th Century, but how people became infected remained a mystery. Many researchers worked to show that malaria was transmitted through inhalation or drinking dirty water. Through years of tireless work in India identifying species of mosquitoes, which were fed on infected patients and then dissected, Ross showed that the parasite lived part of its life in mosquitoes, and that they were responsible for transmitting the disease.
When unable to find human subjects to work on, Ross began to study a closely related parasite in birds. This work revealed the life cycle of the parasite, which it had been impossible to discover in humans. Unlike any creature studied before, the parasite lived most of its life in birds but reproduced inside the stomach of the female mosquito. The parasites then grew in the mosquito’s stomach wall for several days until adult, when they made their way to the salivary glands of the mosquito to be injected into a new host. Now knowing where to look for the parasite at each stage of its life cycle, Ross was finally able to identify which species of mosquito transmitted malaria in humans.