DEVELOPMENT OF DIFFERENT LEISHMANIA-MAJOR STRAINS IN THE VECTOR SANDFLIES PHLEBOTOMUS-PAPATASI AND P-DUBOSCQI

Five lines of four Leishmania major strains, which differ in geographi cal origin and virulence for mice, were used for experimental infectio ns of Phlebotomus papatasi and P. duboscqi. Differences between the li nes, which became evident 6 and 9 days after the infective feed, were more pronounced in P. papatasi. The highest infection rates were found for the more virulent line of strain LV561, while the lowest rates we re recorded for strains L119 (low-virulence for mice) and Neal (avirul ent for mice). Infection rates depended significantly on the Leishmani a strain/line, but not on the vector species. Anterior migration and c olonization of the stomodeal valve were observed in flies infected wit h LV561 and FV1 but infections with other strains were restricted to t he whole midgut (L119) or to the abdominal midgut only (Neal). The pro portions of the different morphological forms of Leishmania seen in gu t smears of infected flies varied considerably with the parasite strai n/line. In general, vector forms of LV561 and FV1 were characterized b y relatively long flagella and bodies. The strains developing less suc cessfully is vectors tended to have a relatively broad body (L119) or short flagellum (Neal). Transmission experiments were successful with P. duboscqi females infected with the virulent line of LV561.