A Two-Years' Survey on the Prevalence of Tuberculosis Caused by Mycobacterium caprae in Red Deer (Cervus elaphus) in the Tyrol, Austria

A survey of 143 hunter-harvested red deer for tuberculosis was conducted in an Alpine area in Western Austria over two subsequent years. There, single tuberculosis cases caused by Mycobacterium caprae had been detected in cattle and red deer over the preceding decade. The area under investigation covered approximately 500？km2, divided into five different hunting plots. Lymph nodes of red deer were examined grossly and microscopically for typical tuberculosis-like lesions and additionally by microbiological culturing. Executing a detailed hunting plan, nine M. caprae isolates were obtained. Six out of nine originated from one single hunting plot with the highest estimated prevalence of tuberculosis, that is, 23.1%. All isolates were genotyped by mycobacterial interspersed repetitive unit—variable number of tandem repeat (MIRU-VNTR) typing of 24 standard loci plus VNTR 1982. All nine isolates belonged to a single cluster termed “Lechtal” which had been found in cattle and red deer in the region, demonstrating a remarkable dominance and stability over ten years. This is the first report on a systematic prospective study investigating the prevalence and strain variability of M. caprae infection in red deer in Austria and in the Alpine countries. 1. Introduction Tuberculosis (TB) is a chronic infectious disease in wildlife caused by bacteria of the Mycobacterium tuberculosis complex (MTC). Several members of the MTC can be distinguished, Mycobacterium caprae being one of them. M. caprae, the aetiological agent found in our study, can infect a wide range of domestic animals, wild animals, and humans [1–3]. Infection in humans with M. caprae appears to be relatively rare and occur preferentially in older patients [4]. Only very few documented autochthonous human cases have been found outside of continental Europe [1]. The body of literature on M. caprae is relatively small, as M. caprae was described as a new subspecies in the MTC only recently in 2003 [3]. Similarly, the role of wildlife in the maintenance and spread of TB is far better studied for M. bovis, [5–9], although most of the findings probably hold true for M. caprae and are therefore briefly highlighted in the following. The best-known European examples of TB reservoir species in wildlife are the Eurasian badger (Meles meles) in the UK and the wild boar (Sus scrofa) in Spain [10, 11]. In 1964, Bischofberger and Nabholz [12] already reported cases of tuberculosis in roe deer (Capreolus capreolus) from Switzerland that appeared to have caused infections in cattle. A recent farm and slaughter survey