This study describes a new focus of cutaneous leishmaniasis (CL) due to Leishmania tropica, in the Galilee region of northern Israel. Thirty-three cases from 4 villages (northern part) and from the city of Tiberias (southern part) have been clinically diagnosed since 1996. Parasites from 13 patients and from 6 sand flies were characterized by isoenzyme electrophoresis, 2 immunological methods, and 3 polymerase chain reaction (PCR)-based methods. Isolates from the northern part were antigenically similar to Leishmania major and were different from other L. tropica isolates, including those from the southern part of the focus. They belonged to a newly reported zymodeme and were separable from all known Israeli L. tropica isolates, by use of 2 different PCR-based methods. Five (5.2%) of 97 Phlebotomus (Adlerius) arabicus and 2 (1.2%) of 162 Phlebotomus (Paraphlebotomus) sergenti females from the northern part of the focus were found to be infected with L. tropica. Three of 29 hyraxes (Procavia capensis) were positive for Leishmania ribosomal DNA. Thus, the northern part of this emerging focus of CL in Israel is distinct from all known L. tropica foci. P. arabicus is the main vector, and it transmits parasites that are different from other L. tropica isolates, with respect to antigenic, molecular, and biochemical parameters.

The predominant sand fly species collected inside houses in Kfar Adumim, an Israeli village in the Judean Desert that is a focus of cutaneous leishmaniasis, was Phlebotomus papatasi, which was also caught attempting to bite humans. Phlebotomus sergenti, which is rarely seen inside houses, constituted the predominant sand fly species in caves near the village. Leishmania isolates from Ph. sergenti and humans typed as Leishmania tropica. Sand fly and human isolates produced similar small nodular cutaneous lesions in hamsters. Isolates produced excreted factor (EF) of subserotypes A(9) or A(9)B(2), characteristic of L. tropica and reacted with L. tropica-specific monoclonal antibodies. Isoenzyme analysis consigned the strains to the L. tropica zymodemes MON-137 and MON-275. Molecular genetic analyses confirmed the strains were L. tropica and intraspecific microheterogeneity was observed. Genomic fingerprinting using a mini-satellite probe separated the L. tropica strains into two clusters that were not entirely congruent with geographic distribution. These results support the heterogeneous nature of L. tropica and incriminate Ph. sergenti as its vector in this Judean Desert focus.

Leishmania parasites are transmitted by the bites of infected female sandflles by a mechanism that has not been clarified. Leishmania infections in the vector develop only in the gut, and the parasites' exit is through the food channel in the proboscis. The problem is how during the bite, when blood flows in, parasites are emitted through the same channel in the opposite direction. It is well documented that infected sandfles maintained on sugar diets are potent vectors, whereas transmission fails after constant feeding on blood. Hence to study the mechanism of transmision, we fed these diets to Phkibotomus papatasi infected with L. maor. Histological examination demonstrated that only in the sugar-fed flies did the cuticle lining of the cardiac valve detach and other valve tissues degenerate gradually. The ijury of the main valve of the food pumps hindered gorging of most flies when force-fed from capillaries, and they regurgitated the gut contents with fluids from the capillaries. We suggest that infections are caused by parasites regurgitated from the stomach that are deposited in the host tissue. We found that secretion of chitinolytic enzymes by cultured L. major parasites is inhibited by blood or hemoglobin, and hence these enzymes are apparently absent from the blood-fed infected flies, where the cardiac valve appears undamaged. We therefore presume that lysis ofthe chitin in the cuticle lining of the valve leads to exposure and degeneration of the underlying tissues.Protozoa parasites of the genus Leishmania (Kinetoplastida: Trypanosomatidae) are causative agents of several diseases that are important public health problems in many countries. The vectors of these parasites are sandflies, and they infect humans and animal reservoirs of the diseases. The developmental cycle ofLeishmania in the sandfly is exclusively in the gut, and parasites reach the host tissue via the food channel in the proboscis. During the bite of infected sandflies the ingested blood is pumped into the gut while at the same time and through the same channel, parasites are deposited in the opposite direction. Evidently, in this system the transmission of the parasites is not implemented by the normal process of ingestion, and additional factors have to be involved. The common opinion was that transmission depends on the presence of parasites in part of the feeding system of the sandfly. The debate was whether parasites facilitate transmission by disturbing the flow of ingested blood or whether they are directly deposited from the proboscis by the act of probing (reviewed in refs. 1-7). These theories were not correlated to transmission experiments, and both the manner and the circumstances of transmission were (8) and still are (9) a major problem in the study of leishmaniasis. We have previously reported that Leishmania major infections in the vector Phlebotomus papatasi cause degeneration of the cardiac valve, the main valve of the feeding system, presum-

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The plant feeding of Phlebotomus papatasi and the effects of plant diets on the Leishmania major infections were investigated. Plant-fed flies had small free particles and membranous shreds in their gut that were stained by calcofluor as cellulosic plant tissues. They were found in 34.0% of the female and 14.3% of the male sand flies following feeding on the caper plant (Capparis spinosa). No plant residues were found in 54 females that had been fed on plant-derived honeydew secretions of Aphis craccivora offered on a branch of the host plant. Calcofluor-stained particles were also absent from the gut lumen of unfed flies. The proportion of sugar feeding, regardless of the intake of plant tissue, in the series that had been offered caper plant or honeydew was estimated by testing for the presence of fructose in the gut. The proportion of fructose-positive flies in each series, among both males and females, was 45%. Plant feeding in the field was demonstrated by finding tissue residues in the gut of 32.8% of female and 10.3% of male P. papatasi from the Jordan Valley. Feeding on specific plants was demonstrated using baits of branches suffused with food dye and finding the dye marker in wild-caught P. papatasi. The influence of plant diets on L. major infections in P. papatasi was as follows: Malva nicaeensis and the honeydew of Icerya purchasi produced thriving parasitemias; however, feeding on Ricinus communis, Capparis spinosa, and Solanum luteum caused > 50% mortality and deformation of parasites in 88%, 55%, and 46% of the infections, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)