The Bovine tuberculosis (TB) and paratuberculosis (Johne’s disease) Symposium at the 2015 JAM: "What we know and what we need to know” provided an excellent overview of both diseases, highlighting both domestic and international opportunities and challenges for the diseases.
Vivek Kapur, Penn State University provided an introduction. He noted that the biology of both diseases is complex and poorly understood. No country is free of the diseases and losses associated with them runs into the billions of dollars. As examples of the scope of the disease, the UK loses about 2% of their cattle population to bovine TB each year and one in ten animals at auction in the US is infected.
Adel M. Talaat, UW- Madison described “A three-year study of bovine tuberculosis in an enzootic area, the Nile Delta.” It provides an opportunity to work in a high prevalence situation where at least one isolate appears to be human related. The need for better diagnostics and whole genome sequencing has been shown.
Holly L. Neibergs, Washington State, reported on” Host genomics—What have we learned?” She shared references to a large number of publications showing that adequate genetic variation exists to make progress in increasing resistance to Johne’s disease with heritability estimates ranging from 1 to 28%. Several potential candidate genes have been identified, and genome-wide association analysis has identified several chromosomes of interest. Genetic change takes a long time, but it is permanent.
Scott Wells topic was “Johne’s disease and bovine tuberculosis: Updates on control and prevention.” He reported on work at Minnesota that verified currently recommended control practices work. Slaughter surveillance works, but it takes a long time. A project in Uruguay is demonstrating the potential of risk based surveillance and the use of social network analysis can help to identify “at risk” farms.
Julie Smith shared ideas on how message mapping and the “Stages of Change” modeling can be valuable tools for sharing information on the diseases and stimulating change.
Tim Bull, Institute of Infection and Immunity, St George’s University of London, London, UK completed the day with a discussion of “Zoonotic potential of bTB and MAP—Nothing to worry about…right?” His bottom line was If MAP is truly a human pathogen, current ineffectual MAP control methods are permitting an extensive, unchecked, worldwide, chronic exposure to humans, some of whom are susceptible to developing disease. Latency and persistence are important characteristics of mycobacterial disease evoking long term immunological influences promoting disease. These states have been difficult to quantitate due to dormant unculturable phenotypes. Better tests are needed but the likelihood is that the extent of bTB and MAP disease burden in humans is not yet fully evident. The threat from bTB and MAP to human health thus remains tangible. Only vigilance currently prevents many potential animal reservoirs becoming re-seeded. Failure to improve screening and eradication tools will continue to allow global spread, increase the risk of human exposure and ensure more trouble is in store.
Overall the session showed the need for better diagnostics and vaccines. Improved animal identification and tracing as well as whole genome sequencing if we are to address the diseases.