West Nile virus outbreak in Israel in 2015: phylogenetic and geographic characterization in humans and mosquitoes.

OBJECTIVES: West Nile Virus (WNV) is endemic in Israel and was responsible for several outbreaks in the past 16 years. The aim of the present study was to investigate the spatial distribution of WNV acute infections from an outbreak that occurred in 2015 in Israel and report the molecular and geographic characterization of WNV isolates from human cases and mosquito pools obtained during this outbreak. METHODS: Using a geographical layer comprising 51 continuous areas of Israel, the number of WNV infection cases per 100 000 people in each area and the locations of WNV-infected mosquitoes in 2015 were analysed. Sequencing and phylogenetic analyses followed by geographic localization were performed on 13 WNV human isolates and 19 WNV-infected mosquito pools. RESULTS: Substantial geographical variation in the prevalence of acute WNV in patients in Israel was found and an overall correlation with WNV-infected mosquitoes. All human patients sequenced were infected only with the Mediterranean subtype of WNV Lineage 1 and resided primarily in the coastal regions in central Israel. In contrast, mosquitoes were infected with both the Mediterranean and Eastern European subtypes of WNV lineage 1; however, only the Mediterranean subtype was found in mosquitoes from the coastal region in central Israel. CONCLUSION: These results demonstrate differential geographic dispersion in Israel of the two WNV subtypes and may also point to a differential pattern of human infections. As a geographical bridge between Europe, Asia and Africa, analysis of WNV circulation in humans and mosquitoes in Israel provides information relevant to WNV infections in Eurasia.

Distribution and seasonality of Phlebotomus sand flies in cutaneous leishmaniasis foci, Judean Desert, Israel.

The ecology of Phlebotomus sand flies in cutaneous leishmaniasis foci as a result of Leishmania tropica in the Judean Desert was studied. Between 2005 and 2007, >265,000 specimens were trapped outdoors and 1,233 specimens were collected indoors. The catches included Phlebotomus sergenti Parrot, Phlebotomus papatasi (Scopoli), Phlebotomus syriacus Adler & Theodor, and Phlebotomus tobbi Adler & Theodor. P. sergenti, the local vector of Leishmania tropica, comprised 90% of outdoor catches, and relatively few were caught indoors. Conversely, P. papatasi were > 90% of the indoor collections, and only a few were caught outdoors. The efficiency of trapping methods varied, but species composition and sex ratio remained constant irrespective of method. Sand flies were abundant on slopes facing east where wind velocity was low, and scarce on slopes facing west and residential areas. Large numbers and high proportion of males that occur near breeding sites were found in man-made rock walls and in rock crevices on slopes of uncultivated hills. Population increase began in April, was more intensive between May and November, peaked in August-September, and significantly decreased in December. Indoors, most of the P. sergenti (< 80%) were collected from September to November. A few sand flies were found between January and March. The effects of climatic factors and human activities on sand fly populations and the risk of Leishmania infections are discussed.

Mosquito vectors of West Nile Fever in Israel.

West Nile fever (WNF) is endemic in Israel. In 1999, country-wide adult mosquito surveys were initiated and intensified after the 2000 country-wide outbreak of WNF in humans. In 8 consecutive yr, groups of male and female specimens of different species and from different locations were tested for infection with West Nile virus (WNV). Three species made up >87% of the total catch: Culex pipiens L. (52%), with an infection rate (IR) of 0.5; Cx. perexiguus Theobald (20%), with an IR of 2.7; and Aedes caspius Pallas (15%), with an IR of 0.6. The geographical and temporal distribution of WNV-infected mosquitoes was similar but was not parallel to the seasonal abundance of the populations. The seasonal occurrence of human cases is in correlation with the finding of WNV-positive mosquito specimens reaching a peak 1 mo later than the mosquito peak. The relative importance of the mosquito species in the epidemiology of WNF is discussed. Cx. perexiguus is considered the major vector of WNF in Israel.

Geographic information system in malaria surveillance: mosquito breeding and imported cases in Israel, 1992.

Although a significant resurgence of malaria in Israel is unlikely at present, the risk for a localized outbreak of malaria cases due to infection of local anopheline mosquitoes by imported cases does exist. A national computerized surveillance system of breeding sites of Anopheles mosquitoes and imported malaria cases was established in 1992 using a geographic information system (GIS). Distances between population centers and breeding sites were calculated, and maps associating epidemiologic and entomologic data were generated. Risk of malaria transmission was assessed with consideration of vectorial capacity and flight range of each Anopheles species. The GIS-based surveillance system ensures that if a localized outbreak does occur, it will be associated rapidly with a likely breeding site, a specific Anopheles vector, and a probable human source, so that prompt control measures can be most efficiently targeted. This cost-effective GIS-based surveillance system can be expanded and adapted for countries with indigenous malaria transmission.