Salivary gland lysates from the sand fly Lutzomyia longipalpis enhance Leishmania infectivity.

Leishmaniasis is a parasitic disease transmitted by phlebotomine sand flies. The role of sand fly saliva in transmission of the disease was investigated by injecting mice with Leishmania major parasites in the presence of homogenized salivary glands from Lutzomyia longipalpis. This procedure resulted in cutaneous lesions of Leishmania major that were routinely five to ten times as large and contained as much as 5000 times as many parasites as controls. With inocula consisting of low numbers of Leishmania major, parasites were detected at the site of injection only when the inoculum also contained salivary gland material. This enhancing effect of sand fly salivary glands on cutaneous leishmaniasis occurred with as little as 10 percent of the contents of one salivary gland of one fly. Material obtained from other bloodsucking arthropods could not mediate the phenomenon.