Occurrence of Mycobacterium avium subsp. paratuberculosis in fecal samples of hunted deer, chamois and ibex in Switzerland.

Mycobacterium avium subsp. paratuberculosis (MAP) is the etiological agent of bovine paratuberculosis, a chronic granulomatous enteritis, also known as Johne's disease. MAP prevalence in domestic food producing animals is increasing globally, causing signifi cant economic losses to the livestock industries through subclinical effects (reduced milk yield and weight loss) and subsequent death of the affected animals. Moreover, several reports suggest a possible link between human Crohn's disease and MAP due to remarkable clinical, epidemiological and pathological similarities (Chacon et al., 2004), but a causal relationship has not yet been proven. Nevertheless, the possible involvement in human disease has led to an increased awareness of these microorganisms as public health concerns. The natural hosts for MAP are domestic ruminants with higher prevalence in dairy and beef cattle herds around the world (Manning and Collins, 2001). For Switzerland, different studies showed a low prevalence of MAP in the cattle population (Glanemann et al., 2004; Bosshard et al., 2006). Wild ruminants may act as a reservoir and contribute to the spread of MAP through fecal shedding (Manning, 2011). Their interaction with susceptible farmed ruminants raises the possibility of playing a role in the epidemiology of the disease in domestic livestock. An interspecies transmission between cattle and wild-living red deer (Cervus elaphus) has been recently proposed by multitarget genotyping of strains from both animal species (Fritsch et al., 2012). However, reported detection rates in wild ruminants vary among different surveys. From fecal samples of red deer a prevalence of 0.1 % has been reported in a Czech Republic survey (Pribylova et al., 2011), whereas a much higher prevalence was found in India where 15 % of hog deer (Axis porcinus) and 57 % of gaur fecal samples (Bos gaurus) were tested positive for MAP (Singh et al., 2010). In view of detection techniques, several culture methods without decontamination or combining chemical or antibiotic decontamination steps and selective media have been proposed (Glanemann et al., 2004; Akineden et al., 2011). However, these methods are time consuming. Immunological-based systems are faster than culture methods but have a low sensitivity (Glanemann et al., 2004; Collins et al., 2005). Molecular based-methods such as PCR assays may represent a rapid screening system for MAP detection. Most of these protocols are based on the IS900 insertion elements but IS900-like sequences found in other Mycobacteria can lead to false positive results. Therefore other sequences without homologues in other Mycobacteria have been proposed; ISMap02 is present in six copies (Stabel and Bannantine, 2005), ISMav2 is present in three copies (Li et al., 2005), and F57 and Hsp X both occur as single copy genes (Tasara and Stephan, 2005). Nevertheless, these methods have a lower sensitivity compared to the cultural based methods and may not detect subclinically infected animals (low shedders). The objectives of this study were a) to investigate the occurrence of MAP in fecal samples collected from hunted wild ruminants by a combination of cultural detection and PCR based identifi cation and b) to asses the impact of wild ruminants in the spread of MAP in Switzerland.