Ticks: Analysing and predicting the occurrence of ticks and tick-borne diseases using GIS

INTRODUCTION For many years, scientific research has considered the relationships between the landscape and human health. Increasing rates of environmental changes are dramatically altering patterns of human health at the community, regional and global scales. The emergence of tick-borne diseases (TBD) illustrates the impact that environmental changes can have on human health. Integration of modern geoinformation technologies into landscape epidemiology can contribute significantly to the development and implementation of new disease-surveillance tools. The theory of landscape epidemiology offers the opportunity to use the landscape as a key to the identification of the spatial and temporal distribution of disease risk. Key environmental elements – including elevation, temperature, rainfall and humidity – influence the presence, development, activity and longevity of pathogens, vectors and zoonotic reservoirs of infection, and their interactions with humans (Meade, Florin & Gesler, 1988). The same environmental variables influence distribution of vegetation type as landscape elements and patterns of disease. Remote sensing (RS) from aircraft and satellites can be used to describe landscape elements that influence the patterns and prevalence of disease. In addition, geographical information systems (GIS) provide tools for modelling spatially their occurrence in space and time. Ticks are ideally suited to GIS and RS applications owing to their close ties with the ecosystem. This relationship is determined by: (1) the type of host–parasite association (most important vector species are three-host ticks); (2) specific requirements of the microclimate; and (3) dependence on clearly defined types of plant associations which both reflect the microclimatic conditions of a habitat occupied by ticks, and also influence them.