In 1880, Alphonse Laveran discovered that a parasite was the causative agent for malaria. In 1886, Camillo Golgi showed that in some patients, there was a relationship between the parasites' 72-hour life cycle of development and a similar periodicity of the chill and fever pattern. In contrast, in other patients, there were 48-hour development cycles. Golgi thus concluded that more than one malaria parasite species must be responsible for the different patterns of cyclical infection.
In 1890, Italian investigators Giovanni Batista Grassi and Raimondo Filetti introduced Plasmodium vivax and Plasmodium malariae. Grassi was also the first to describe the parasites' life cycle in 1899.
Plasmodium falciparum was named in 1897 by American William H. Welch. Also, in 1897, a British officer named Ronald Ross discovered that humans could pass the malaria parasite onto mosquitoes by releasing malaria-free mosquitoes in the rooms of malaria patients.
The fourth malarial parasite, Plasmodium ovale was found in 1922 by John W. W. Stephens.
