Ronald Ross is widely credited with discovering the transmission of malaria by mosquitoes, a milestone that established the vector-based understanding of the disease. Key points

• Early observations: The concept that malaria could be transmitted by a mosquito emerged from work by several scientists in the late 19th century, including Charles Laveran (who identified the parasite in human blood) and Patrick Manson (who proposed a vascular transmission to humans and helped link mosquitoes to transmission).

• Breakthrough attributed to Ross: In 1897, Sir Ronald Ross demonstrated that malaria parasites could develop within the stomach of the female Anopheles mosquito after feeding on a malaria-infected host, and that the parasite could later be transmitted to a new host. This work led to a published report in 1897 and is commonly cited as the decisive proof of mosquito-borne malaria transmission.

• Context and significance: Ross’s discovery connected the life cycle of the parasite to the mosquito vector, paving the way for vector control strategies and a deeper understanding of malaria biology. The broader historical record also recognizes Laveran’s earlier identification of the malaria parasite in human blood (1880) and Manson’s contributions to the epidemiology of the disease.

Direct answer
The discovery that malaria is transmitted by mosquitoes is chiefly credited to Sir Ronald Ross, who, in 1897, demonstrated that the malaria parasite develops inside the gut of the female Anopheles mosquito after a blood meal and can be transmitted to humans, establishing the vector-based mechanism of malaria transmission. This achievement built on earlier foundational work by Charles Louis Alphonse Laveran (identifying the parasite in human blood) and Patrick Manson’s epidemiological insights, but Ross is the figure most commonly celebrated for proving the mosquito transmission pathway.