The major health importance of sand flies is their capability of transmitting the zoonotic protozoan Leishmania group. Worldwide, leishmaniosis is one of the most important vector-borne diseases (besides malaria, lymphatic filariosis and sleeping sickness) and presents as a large variety of disease manifestations differing markedly in their severity and health impact.

Besides, sand flies are also known transmitters of the bacteria Bartonella baciliformis, the infectious agent of the Oroya fever, and of the sand fly fever virus that lead to Pappataci fever or sand fly fever. Pappataci fever is a human disease in the Mediterranean basin, in Middle Asia up to India and in South America.