[4] They were the first to distinguish symptoms of Plasmodium falciparum, the causative agent of tertian malaria, from benign forms.

They found that the malaria parasites were spherical in nature (rather than filamentous, as generally believed), mainly intraerythrocytic (rather than free living), that the liberation of spores at segmentation (schizont rupture) caused fever, and that there were different species of malaria parasites (each with its own different characteristics, notably fever periodicity).

To show this, he captured mosquitoes in areas with high incidence of malaria and had them bite healthy people.

But, like Sir Ronald Ross, a British Army surgeon working in India on the same mission (following Patrick Manson's mosquito-malaria theory), he failed to find direct evidence.

In 1898, Bignami, Giovanni Battista Grassi, Antonio Dionisi and Giuseppe Bastianelli's experiments succeeded.

[1][7][8] Bignami's major works include Ricerche sull’anatomia patologica delle perniciose (1890), Sulle febbre malariche estivo-automnali(1892) or On Summer-Autumnal Fevers (1894), La malaria e le zanzare (1899), La infezione malarica (1902) and with Grassi, Ciclo evolutivo della semilune nell' Anopheles claviger (1899).