Leishmaniasis in the Jordan Valley II. Sandflies and transmission in the central endemic area

Abstract

Cutaneous leishmaniasis in the Jordan Valley is maintained within the close association of the rodent Psammomys obesus and sandfly Phlebotomus papatasi, which appear to be the exclusive host and vector species. The incidence of the disease was similar to the distribution of Psammomys colonies in the region, i.e., the plains of light stoneless soil. An infection rate of 93% was recorded in the very common P. obesus. Other potential host species, except for Mus musculus, were scarce and no infection with Leishmania was found in them. The only Phlebotomus species caught in significant numbers was Ph. papatasi and this was also the only species harbouring leishmanial parasites, up to 56% in one sample. All Leishmania isolates from Psammomys and from Ph. papatasi were identical to those from local human cases. The density of Ph. papatasi populations in uncultivated areas was correlated with soil conditions favouring high humidity in Psammomys burrows. A very low rate of engorged females among the Sergentomyia species collected suggests that the common species, S. antennata and S. africana asiatica, are highly autogenous.

Glycolytic and chitinolytic activities of Phlebotomus papatasi (Diptera: Psychodidae) from diverse ecological habitats

“…Four colonies of the phlebotomine sand fly P. papatasi were maintained under identical conditions at a temperature of 26 ± 1°C and 80% R.H. The four colonies derived from progenitor flies caught in the following places in Israel: Neot Hakikar (352 m below sea level), a salt marsh oasis with lush vegetation in the southern Jordan Valley, where 10-12% of the reservoir host Psammomys obesus Cretzschmar, 1828, is infected with L. major (Wasserberg et al 2003, Müller andSchlein 2004); Kfar Adumim (350 m above sea level), 15 km east of Jerusalem, where L. major is absent, but P. papatasi are frequently found in houses (Schnur et al 2004) and Gilgal (253 m below sea level), an arid area 30 km north of Jericho in the Jordan Valley, which is endemic for L. major and up to 90% of P. obesus are infected (Schlein et al 1982, Schlein and. Two separate colonies were started from Gilgal, one from flies trapped at the beginning of the season (spring, mean annual rainfall is approximately 80 mm), when there are islands of green vegetation, and the other from flies at the end of the season (dry summer -autumn) when the vegetation is sparse.…”

A comprehensive account of species composition, distribution and ecology of phlebotomine sandflies in Jordan

“…Therefore, this species is suspected of being the vector of /.. major throughout the country. This is supported by the fact that it is a proven vector of this parasite in surroun ding countries such as Israel (Schlein et al, 1982) and Saudi Arabia (Killick-Kendrick et al, 1985). (Jaffe et al, 1988).…”

“The little sister” — a tale of Arabia

“…High infection rates have been recorded (KILLICK-KENDRICK et al, 1985b). Some 35% of flies dissected in 1983 contained flagellates and much higher rates have been found since then, paralleling the situation in the Jordan Valley (SCHLEIN et al, 1982). The wDulation size of this $lebotomine, which iaries c&iderably throughout the year, begins to increase in about April as the ambient temperature rises.…”

“…The result is that the flies are diverted to man. The data on infection rates of Psammomvs with Leishmunia suggest that probably 100% of tile animals are infected during their lifetime, making them the perfect animal reservoir for this zoonosis (ELBIHARI er al., 1987a), this Situation again paralleling that in the Jordan Valley (SCHLEIN et al, 1982). Canine infection with L. ma& was found for the first time in a few animals amoig the packs of feral dogs that roam many of the deserts of Arabia, but it seems more likely that they are, like man, victims rather than reservoirs of ZCL (ELBIHARI et al, 1987b).…”