SUSCEPTIBILITY TO LEISHMANIA-MAJOR OF DIFFERENT POPULATIONS OF PHLEBOTOMUS-PAPATASI (DIPTERA, PSYCHODIDAE) FROM ENDEMIC AND NONENDEMIC REGIONS OF EGYPT

The ability of three populations of Phlebotomus papatasi collected fro m different areas of Egypt (Sinai, Aswan and Delta regions) to acquire successfully and transmit Leishmania major (Sinai sandfly isolate IPA P/EG/89/SI-177) was evaluated in the laboratory. Flies from each popul ation were fed artificially on infected blood suspensions, using a chi ck-skin-membrane feeding apparatus, and naturally on infected mice. Sa mples of fed flies were dissected and examined microscopically to dete rmine the infection rate and intensity of parasite infection. The Aswa n population had a significantly lower feeding rate (16.2%) than the S inai (51.2%) and Delta (69.7%) populations (P < 0.0001). The infection rate for the Sinai population was significantly higher (65.9%) than t he rate for the Delta (52.3%; P < 0.05) and slightly higher than that for the Aswan (62.5%). No differences were observed in the intensity o f L. major infection in the midguts of the sandflies examined from any of the three populations. When flies from each population were fed na turally on BALB/c mice infected with L. major, the feeding rates of th e three populations showed a similar pattern to that seen in the membr ane feeds, with the Aswan population having the lowest rate. In each o f two separate trials for each population, a group of artificially inf ected flies was refed on uninfected BALB/c mice. Thirty-six days follo wing exposure to the infected sandflies in the Sinai population, a lei shmanial lesion was observed on the corner of one animal's mouth. Thes e observations provide the final piece of evidence that P. papatasi is a vector of L. major in Egypt.