Mycobacterium avium subspecies paratuberculosis is a very slow growing mycobactin-dependent member of the Mycobacterium avium complex. Unlike other M. avium species, M. avium subspecies paratuberculosis has the specific ability to cause chronic inflammation of the intestine, Johne's disease which can affect many species including primates. Despite its broad pathogenicity M. avium subspecies paratuberculosis can live in animals for years without causing clinical disease. Subclinical infection is widespread in domestic livestock especially cattle, sheep, and goats. Europe and North America have been particularly affected, but infection and disease are now spreading worldwide. Clinically and subclinically infected animals shed M. avium subspecies paratuberculosis in their milk. These pathogens are more robust than M. bovis. Research so far carried out in the UK, USA and Czech Republic shows that M. avium subspecies paratuberculosis is from time to time transmitted to human populations in retail milk supplies. Recent research from several centres using appropriate laboratory methods shows that most people with chronic inflammation of the intestine of the Crohn's disease type are infected with these chronic enteric pathogens. Like Johne's disease, the incidence of Crohn's disease is increasing particularly in children.
Ultimately we wish to progress towards a multidisciplinary program of research designed to inform future policy decisions with quantitative data on the level of environmental contamination by MAP and provide the essential quantitative basis for future testing of the efficacy of potential remedial measures such as the use of new generation veterinary vaccines to minimise environmental contamination and cycling. However, in order to achieve this we have to understand the fate and behaviour of MAP in a number of environmental compartments as specified by our model (see reference; for instance, rivers, sediments, aerosols) through quantification and source identification in order to test the hypothesis that Mycobacterium avium subspecies paratuberculosis contaminating environmental compartments constitutes a significant and incremental threat to human health.
Pickup, R.W., Rhodes, G., Bull, T.J, Arnott, S., Sidi-Boumedine, K., Hurley, M.J. and Hermon-Taylor, J. (2006). Mycobacterium avium subspecies paratuberculosis in lake catchments, in river water sourced for domestic supply and in effluent from domestic sewage treatment works: diverse opportunities for environmental cycling and human exposure. Applied and Environmental Microbiology 72, 4067-4077.
M. immunogenum, a known human pathogen is a recently described species and has as closest relatives M. chelonae, M. abscessus. Collectively these bacteria form the M. chelonae complex. In recent years M. immunogenum has been implicated in the causation of hypersensitivity pneumonitis (HP) in automobile workers and other occupational workers exposed to metal working fluids. The early detection of M. immunogenum and related bacteria may be important in the possible prevention of HP. Since developing a highly specific quantitative PCR detection method, our interests now focus on its source, diversity and role in hypersensitivity pneumonitis.
Rhodes, G., Fluri, A., Gerber, M., Henderson, A. & Pickup R.W. (2008). Detection of Mycobacterium immunogenum by real-time Taqman PCR. Journal of Microbiological Methods 73, 266-268.