The utility of GIS in studying the distribution of Bovine Tuberculosis in wild boar (Sus scrofa) and red deer (Cervus elaphus) in Central Portugal

Abstract

Tuberculosis in game animals has gained, in the past few years, an increasing significance in the central region of Portugal, mainly in wild ungulates such as red deer (Cervus elaphus) and wild boar (Sus scrofa). Geographical Information Systems (GIS) technology is becoming an essential component of modern disease surveillance systems. In this study GIS was used to evaluate the geographical distribution of Bovine Tuberculosis (BT) in large game species in Central Portugal. Sampling plots for GIS were mapped by means of a GPS (Global Positioning System) receiver in Idanha-a-Nova county (lat 39° 55’ N: long 7° 14’ W) from November 2008 to February 2009. Over this period, 526 animals (337 red deer (Cervus elaphus), 142 wild boars (Sus scrofa), 29 fallow deer (Dama dama), and 18 mouflon (Ovis musimon)) were analysed for BT lesions, during meat inspection. From these harvested animals, 73 (13.88%) carried BT compatible lesions, which were later confirmed by laboratorial analysis. Data collected during fieldwork were assigned to each sampling plot location, in order to enable geostatistical analysis. The analyses of the BT intensity map, created by GIS, for wild boar and red deer hunted in Central Portugal, allow the conclusion that the main BT-afected areas were located at the south-east area of the county. These areas should be the first ones under veterinarian scrutiny with a view to control or reduce disease spread and prevalence. GIS provided an important tool to define objective strategies for preventing the spread of infectious disease.