The use of multi-criteria evaluation for the selection of study plots for monitoring of I. ricinus ticks - Example from Central Europe.

Research projects in the field of eco-epidemiology of tick-borne diseases often require extensive sampling of arthropod vectors in the field. The aim of our study was to use geographical information systems (GIS) to select appropriate sampling sites of Ixodes ricinus ticks in central European habitat for further ecological studies of vector-borne pathogens (tick-borne encephalitis virus and Borrelia burgdorferi sensu lato). The model area was the Czech-German borderland (the region of South Bohemia and two regions in Germany: the Upper Palatinate and Lower Bavaria) where numerous human tick-borne encephalitis cases are reported annually. We prepared the sampling site design as a multi-criteria evaluation (MCE) task. In the GIS environment, we conducted MCE with a set of environmental, socio-economic and epidemiological data (altitude, vegetation cover, number of tick-borne encephalitis cases recorded in the past, tourist activity). The MCE classified the surveyed area into two classes: suitable for tick collection and unsuitable for tick collection. Subsequently, 50 tick sampling sites were randomly selected in the suitable area: 30 in South Bohemia (Czech Republic) and 20 in the Upper Palatinate and Lower Bavaria regions (Bavaria, Germany). The sampling sites were identified and surveyed in the field. The presence of ticks was confirmed by flagging at each of the selected plots. The described MCE system represents a versatile tool for semi-randomized design of tick sampling sites for research projects in the field of tick-borne pathogen ecology as well as for tick-borne pathogen surveillance programs run by local health authorities.