Use of Knowledge Synthesis and Translation Methodologies as the Basis of an Evidence Informed Evaluation of Mycobacterium avium ssp. paratuberculosis
A mixed methods approach was undertaken to develop an evidence-informed evaluation of the public health implications of Mycobacterium avium subsp. paratuberculosis. An assessment of the methodological quality of 132 literature reviews published 2000-2006 on zoonotic public health issues showed a considerable need for improvement. A scoping study on sources and routes of human exposure to M. paratuberculosis summarized 255 publications that reported prevalence or concentration of M. paratuberculosis in various sources of human exposure. Significant risk factors for developing Crohn’s disease in humans included consumption of processed meats and cheese, but not direct contact with ruminants, membership in suspected high risk occupations, milk consumption or water source. Systematic review meta-analysis on the zoonotic potential of M. paratuberculosis summarized 128 papers that examined associations with Crohn’s disease, human immunodeficiency virus infection, sarcoidosis, diabetes mellitus, multiple sclerosis and Hashimoto’s thyroiditis. There were consistent, significant positive associations with Crohn’s disease, diabetes mellitus type 1 and multiple sclerosis. A web-based survey showed that M. paratuberculosis topic specialists considered the agent likely to be a risk to human health (44.8%) and a moderate public health issue (40.1%). Topic specialists largely agreed (68.4%) that further enhancement of on-farm programs is most appropriate and further involvement by government (92%) is unnessecary given the current state of evidence. Finally, a risk profile for M. paratuberculosis was undertaken to summarize the information assembled in preceding chapters relevant to a public health evaluation of M. paratuberculosis. The evidence for the zoonotic potential of this agent is weak, but consistent across published studies, and topic specialists agree that M. paratuberculosis should be considered a moderate public health issue. However, the evidence is not yet sufficient to warrant specific risk management efforts. The existence of critical knowledge gaps and resultant uncertainties helps to explain why researchers interpret the available research differently and sometimes provide conflicting opinions and advice. While many critical knowledge gaps remain, this potential public health issue cannot be ignored and research advances and mitigation activities should continue to be monitored and periodically evaluated to re-affirm the appropriate level of action is being taken.