Using wild deer as sentinels reveals spatial variation in the abundance and diversity of Mycobacteria in northeast Scotland

Abstract

Mycobacterium spp. are a diverse genus of environmentally transmitted bacteria that includes key pathogens of humans and livestock, as well as species that can interfere with diagnostic testing for these diseases. Different habitats harbour different mycobacterial communities so understanding which Mycobacterium spp. ruminants are exposed to in different habitats is important to assess potential disease risk and diagnostic test interference. Due to their widespread distribution, wild deer may serve as sentinels to assess exposure to mycobacterial communities in ruminant livestock across different habitats and landscapes. Using faecal samples from culled wild red (Cervus elaphus) and roe (Capreolus capreolus) deer from a lowland and a highland site in northeast Scotland, we used molecular approaches to identify and characterise mycobacterial diversity and community composition at these sites using the hsp65 gene. Mycobacterial prevalence was significantly lower in the highland site compared to the lowland site. Diversity and community composition also significantly differed between sites. Within sites, mycobacterial community composition differed between deer species, potentially due to differing habitat use and feeding ecologies. Characterisation of mycobacterial diversity revealed numerous novel genotypes, many of which were closely related to opportunistic pathogen species, or species known to interfere with diagnostic testing. These findings highlight the usefulness of wild deer as sentinels for understanding the ecology of environmentally transmitted pathogens such as Mycobacterium spp., in different environments and assessing potential exposure risk in ruminant livestock.