Phlebotomine sand flies (Diptera: Psychodidae) of the Palestinian West Bank: potential vectors of leishmaniasis.

Two forms of leishmaniasis are endemic to the Jenin district in the northern region of the West Bank. Visceral leishmaniasis (VL), caused by Leishmania infantum, mainly affects infants. Cutaneous leishmaniasis (CL) affects a broader age group and is probably caused by L. tropica. Although the Jenin district is the most important focus of leishmaniasis in the West Bank, the sand fly fauna of the area has never been studied in a systematic manner. We collected base-line data on sand fly species, their distribution, and their feeding preferences to facilitate risk assessments for contracting leishmaniasis. Light traps, sticky traps, insecticide knockdown collections, aspirator, and human-landing collections were used. A total of 4,082 sand flies was collected in foci of confidence limits and/or VL between June and December 1998. Nine Phlebotomus species representing seven subgenera were identified: P. (Larroussius) perfiliewi transcaucasicus Perfil'ev, P. (La.) tobbi Adler & Theodor, P. (La.) mascitti canaaniticus Adler & Theodor, P. (La.) mascitti mascitti Grassi, P. (La.) syriacus Adler & Theodor, P. (Phlebotomus) papatasi Scopoli, P. (Synphlebotomus) s.p., P. (Paraphlebotomus) sergenti Parrot, P. (Par.) jacusieli Theodor, P. (Adlerius) halepensis Theodor. Two other Phlebotomus subspecies, P. (La.) major major Annandale, P. (La .) neglectus Tonnoir, require confirmation. In addition, four species of the closely related genus, Sergentomyia were also found: S. (Sergentomyia) theodori Parrot, S. (S.) fallax Parrot, S. (Sintonitus) tiberiadis Adler, Theodor & Lourie, S. (Sin.) christophersi Sinton. Among five species of sand flies collected on human bait, P. papatasi constituted approximately 90% followed by P. major syriacus (8%) and P. mascitti (2%). Sand fly human-biting activity occurred through the night and it was highest between 2400 and 0300 hours. P. papatasi. P. perfiliewi, P. major and P. tobbi were the more endophilic species constituting 93% of all flies caught indoors. Seven Phlebotomus spp. constitute potential vectors of leishmaniasis but the most probable ones are as follows: P. papatasi the main human-biting species, a recognized vector of L. major (CL), P. sergenti, L. tropica (CL) and P. syriacus, L. infantum (VL).

Epidemiology of visceral leishmaniasis in the Jenin District, West Bank: 1989-1998.

Fifty patients from rural areas in the Jenin district of the West Bank, Palestinian Authority, were diagnosed with visceral leishmaniasis (VL) between 1989 and 1998. Forty-nine (98%) were younger than 6 years old, the youngest being 9 months. The yearly incident rate of VL in the Jenin district was highest in 1994 (11.8/100,000) and decreased to 1.5/100,000 in 1998; a mortality rate of 4% was recorded. Seventeen (5.5%) of 308 dogs from the Jenin and Ramallah districts of the West Bank were seropositive by enzyme-linked immunosorbent assay in a survey of canine leishmaniasis. Although all the leishmanial strains cultured from humans and dogs were identified as Leishmania infantum by a species-specific polymerase chain reaction, further genetic analysis by restriction fragment length polymorphism of kinetoplast DNA revealed patterns of polymorphism within isolates. The findings indicate that an active focus of potentially fatal VL exits in the Jenin district of the West Bank and that the parasite, vector, and reservoir host are found in this area. The epidemiology of VL in that vicinity follows the pattern of a predominantly infantile disease traditionally found in Middle Eastern countries, without a considerable involvement of immunocompromised adults infected with HIV virus as reported in other regions.