The ecology of cutaneous leishmaniasis in Nizzana, Israel: infection patterns in the reservoir host, and epidemiological implications G. Wasserberg a, * , Z. Abramsky a , G. Anders b , M. El-Fari c , G. Schoenian c , L. Schnur b , B.P. Kotler d , I. Kabalo e , A. Warburg b a Department of Life Sciences, Ben-Gurion University of the Negev, PO Box 653 Beer-Sheva, 84105, Israel b Department of Parasitology, The Kuvin Centre for the Study of Infectious and Tropical Diseases, The Hebrew University-Hadassah Medical School, Ein Kerem, Jerusalem 91220, Israel c Institut fuer Mikrobiologie und Hygiene, Charite Campus Mitte, Dorotheenstrasse 96, D-10117 Berlin, Germany d Mitrani department of Desert Ecology, Jacob Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, 84990, Israel e Public health unit, The Southern Command Health Corps, Israel Defence Force, Mahane Natan, Beer-Sheva, Israel Received 23 August 2001; received in revised form 25 October 2001; accepted 25 October 2001 Abstract We conducted an extensive interdisciplinary study in an emerging focus of cutaneous leishmaniasis in the Western Negev Desert of Israel between July 1998 and February 2000. The aims of the this study were to determine (1) the reservoir hosts, (2) the distribution of the pathogen within the host range, (3) the associations of host, vector, and pathogen within defined habitats, (4) the demographic distribution of the pathogen within the host populations, and (5) to apply the newly acquired epizootiological data to explain morbidity patterns in humans. Fourteen square (60 m width) sampling plots were delimited in three types of habitats each with a different kind of substrate: loess, sand, and sand–loess ecotone. Rodents and sand flies were trapped and several environmental variables were measured. Leishmania infections in rodents were detected microscopically in stained smears of ear tissue and by a Leishmania-specific polymerase chain reaction. Results indicate that, contrary to previous reports, Psammomys obesus and not Meriones crassus is the main reservoir host in the region. Additional rodents (12 Gerbillus dasyurus and two M. crassus) were also found positive for Leishmania DNA. Prevalence of Leishmania infections amongst P. obesus was highest in loess habitats (65%), intermediate in the sandy–loess ecotone (20%), and 0% in the sandy habitats. Psammomys obesus individuals in the loess habitat of the Nizzana ruins were larger, on average (probably older), than those in the sandy habitat of the Mt. Keren junction. Sand fly density was positively correlated to soil moisture being higher in the relatively humid plots of Nizzana ruins and much lower in the drier sandy soil of Mt. Keren. Elucidation of fundamental ecological factors affecting this disease has helped explain an apparent discrepancy between the distribution of the disease in the zoonotic system and among humans. q 2002 Australian Society for Parasitology Inc. Published by Elsevier Science Ltd. All rights reserved. Keywords: Zoonosis; Cutaneous leishmaniasis; Epidemiology; Disease distribution; Psammomys obesus; Nizzana 1. Introduction Zoonotic diseases are highly complex ecological systems and a profound understanding of their structure is essential for the effective implementation of control measures (Audy, 1958; Pavlovsky, 1966; Muul, 1970; Carey et al., 1980; Sousa and Grosholtz, 1991; Mollison and Levin, 1995; Ashford, 1996, 1997, 2000; Ostfeld, 1997; Mills and Childs, 1998; Murphy, 1998; Schmidt and Ostfeld, 2001). Small mammals, mostly rodents, frequently serve as the reservoir hosts to many zoonoses, yet their function in the cycle of transmission is all too often, the least studied (Muul, 1970; Ashford and Bettini, 1987; Ashford, 1996, 1997, 2000; Ostfeld, 1997; Mills and Childs, 1998). The past few years have witnessed a renewed interest in the study of reservoir ecology owing to the emergence and resurgence of many rodent-borne human diseases like some viral hemorrhagic fevers (Mills and Childs, 1998), the leishma- niases (Ashford, 2000; Desjeux, 2001), and Lyme disease (Ostfeld, 1997). Assuming the primary reservoir host has been implicated, Mills and Childs (1998) emphasise six major steps to be addressed in the study of zoonoses. These are: (1) determi- nation of the geographic distribution of the host; (2) deter- mination of the geographic range of the pathogen within the International Journal for Parasitology 32 (2002) 133–143 0020-7519/02/$20.00 q 2002 Australian Society for Parasitology Inc. Published by Elsevier Science Ltd. All rights reserved. PII: S0020-7519(01)00326-5 www.parasitology-online.com * Corresponding author. Tel.: 1972-8-6472633; fax: 1972-8-6472992. E-mail address: gwasser@bgumail.bgu.ac.il (G. Wasserberg).