How did Ronald Ross show that mosquitoes spread malaria?

Sir Ronald Ross demonstrated that mosquitoes transmit malaria by conducting a series of investigations, guided by Patrick Manson, beginning in 1895.1

In 1897, Ross discovered the presence of malarial parasites within the gastrointestinal tract of an Anopheles mosquito. To confirm the transmission mechanism, he utilized birds infected with malaria and successfully traced the entire life cycle of the parasite, identifying its presence in the mosquito’s salivary glands. He subsequently demonstrated that the disease could be transmitted from infected birds to healthy ones through mosquito bites, a finding that provided the critical evidence for how the disease spreads to humans.1

This discovery, for which Ross was awarded the Nobel Prize in 1902, fundamentally changed the understanding of malaria, which had previously been incorrectly attributed to "bad air" or stagnant water vapors. His work laid the essential foundation for modern public health strategies, such as mosquito control and drainage, which have been vital in combating the disease globally.12