RECOMMENDATION 21. The National Institutes of Health or similar body should convene a panel with experts in gastroenterology, Crohn’s disease, infectious disease, mycobacteriology, biostatistics, epidemiology, etc., to define the precise study designs and to rank order the various studies to be done.

Although the committee did not find sufficient evidence to implicate Map as a cause of Crohn’s disease, there was consensus that efforts to identify and mitigate avenues of exposure to Map would be prudent while awaiting definitive resolution of this important question. Identifying environmental sources of Map also is an important element of JD control in livestock, so there is additional justification for such investigations. The committee therefore recommends researching the following projects:

RECOMMENDATION 22. Research should be conducted to determine the prevalence of viable Map in potable-water supplies, streams, ponds, and other bodies of water with potential for Map contamination. This could require development of better methods for identifying and quantifying Map in environmental samples.

RECOMMENDATION 23. Additional studies are needed to determine whether Map is present in retail milk or other dairy products, as well as in pasteurized colostrum or commercial colostrum replacers that are fed to calves.

RECOMMENDATION 24. Research should be done to determine the prevalence of viable Map in peripheral lymph nodes, muscle, and other tissues that are processed for human consumption.

RECOMMENDATION 25. Research should be done to determine the prevalence and concentration of Map in other environmental materials likely to be contaminated with ruminant manure and associated with exposure to humans or susceptible animals. Those materials could include composted manure, fruits and vegetables, pastures, and crops fed to livestock.

If a causal relationship is established between human Map infection and a subset of Crohn’s disease cases, the above research recommendations will be essential for implementation of new control programs aimed at protecting public health by minimizing exposure to Map. Additional research would then be needed to develop methods for routine screening of dairy products, meat, and meat products for Map.

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