Lyme borreliosis is a multi-system disorder which can affect a complex range of tissues including the skin, joints, central and peripheral nervous system, and several internal organs. Since this disease is endemic in the Karst area around Trieste, where it is transmitted by ticks, this study project aims at assessing how borrelia and encephalitis infected ticks vary over time, and at comparing the data obtained with the clinical data concerning the incidence of Lyme disease and TBE meningitis. Owing to the complexity of this disease andin order to foster prevention, an information campaign is going to be carried out in schools, health facilities and in general all places visited by a large number of people (especially youth aggregation centres); bilingual brochures, guidelines and posters containing a mapping of the area where ticks are to be found are going to be handed out, together with a detailed description of prevention methods, first aid measures and the peculiarities of the Lyme disease. Moreover, scientific meetings and thematic seminars are going to be held, in order to discuss and compare the available information (e.g. with regard to the ticks biological characteristics and the climatic-environmental factors which favour their activity, such as relative humidity, temperature, type of soil, presence of host animals, microclimate and vegetation). Finally, in each partner municipality, a Lyme observing unit is going to be set up; this unit will monitor the tick bite cases, providing a quarterly report for the central organizing unit, that will include it in the common database, and will distribute information material to the population.