Wildlife tuberculosis: a systematic review of the epidemiology in the Iberian Peninsula

Abstract

Wildlife tuberculosis emerged in the last decades as an important hurdle to the eradication of bovine tuberculosis in several European countries. Much has been published since on the epidemiology of wildlife tuberculosis in Iberian Peninsula, but no systematic review has been conducted. In this paper we present a systematic review of published papers on the epidemiology of wildlife tuberculosis in Portugal and Spain. Most studies are cross-sectional, relying on targeted collection of samples from hunted ungulates and use bacteriological culture as diagnostic test, usually after screening for macroscopic lesions. Seven species of wild ungulates and three of carnivores have been found infected in Iberian Peninsula. Wildlife tuberculosis seems to persist in a multi-host ecosystem, with wild boar and red deer as the most frequent maintenance hosts. Prevalence rates in these two species are among the highest recorded (0,02-1 for wild boar, 0,01-0,44 for red deer). Fallow deer and badger could also be important maintenance hosts, although in circumscribed locations. Wildlife tuberculosis seems to be emerging, both spatially and in prevalence, from a core area in south-western Iberia. This emergence seems to be fuelled by increasingly intensive management of populations of these species for hunting purposes. Molecular epidemiology produced evidence of local transmission between wild and domestic species. Nevertheless vital data is still unavailable, such as on the detailed geographical extent of the disease, intra and inter-species transmission routes and determinants of disease. Epidemiological studies following case-control and experimental designs, modeling and spatial analysis could shed light on this subject.