Mosquito-borne diseases have been recorded in human history for thousands of years as major causes of disability and death. No one, however, realised mosquitoes were vectors of the diseases until the end of the 19th century. The first breakthrough came in 1877 when British doctor Patrick Manson discovered that a Culex species of mosquito could carry the human filarial roundworm.
Over the next two decades, he and other researchers from France, Italy, Russia, and the USA turned to malaria, a major killer in tropical and temperate countries. They slowly completed the complex jigsaw of malaria transmission and biology in humans and mosquitoes.
In 1894, Manson persuaded Ronald Ross, a medical officer in the Indian Medical Service, to study mosquitoes as the likely vector of the malaria parasite. After years of fruitless research, Ross finally proved in 1897 that Anopheles mosquitoes could carry the malaria parasite. He called the day of his discovery, 20 August 1897, “Mosquito Day.” The London School of Hygiene and Tropical Medicine later named 20 August World Mosquito Day to mark the significance of his discovery, which is celebrated annually.
This critical link to the Anopheles mosquito also showed that practical measures to prevent mosquito bites and control mosquito populations — vector control — could be used to prevent malaria.