World Mosquito Day, observed on 20 August, raises awareness of mosquito-borne diseases and their prevention. It marks Sir Ronald Ross's discovery in 1897 that female Anopheles mosquitoes transmit malaria parasites to humans. Ross, a British-Indian physician born in Almora in 1857, won the 1902 Nobel Prize in Physiology or Medicine, becoming the first British Nobel laureate in medicine. Major mosquito-borne diseases include malaria, dengue, chikungunya, Japanese encephalitis and Zika; malaria spreads mainly through female Anopheles, while dengue and chikungunya spread mainly through Aedes mosquitoes.