Project code: DCNI-D-25-04

Duration 12 Months completing December 2005

Team and Leader

Organisations Involved  Dairy Council for Northern Ireland, Q.U.B. Newforge Lane.

Background and Summary

Mycobacterium avium subsp. paratuberucolosis (MAP), causes Johne's disease (JD) in cattle. Infected dairy cows shed the organism in faeces and in milk. Although not accepted as proven, there is a growing body of medical opinion that suggests that MAP may be a causative agent of Crohn's Disease (CD) in humans. 

A recent article in the Lancet, reporting on research in USA, concluded "We detected viable MAP in peripheral blood in a higher proportion of individuals with CD than in controls. These data contribute to the evidence that MAP might be a cause of CD". If this is the case, then a vehicle of transmission of MAP to humans could be milk.

MAP has been found in pasteurised milk in UK (Grant et al., 2002), and work at QUB, jointly funded by Agri-Search, demonstrated that it can survive pasteurisation at regimes more stringent than those normally used in commercial practise. In addition, recent research at QUB (Donaghy et al., 2004), has demonstrated that MAP can, but not necessarily does survive cheddar cheese manufacture.

The dairy industry, worldwide, is presented with a dilemma. MAP, which is a class 2 pathogen, has been shown to survive commercial pasteurisation and, at laboratory scale, Cheddar cheese manufacture. Research undertaken at the Hannah Research Institute, and not yet published, is unlikely to provide a processing solution to this problem. Some countries, such as Australia, Canada, and some States in USA, have instigated JD eradication programmes. The difficulty with this approach is that it can take up to 30 years for an infected herd to be declared JD free (this is an estimate provided at a seminar organised by the International Dairy Federation, 2000). In recognition of the importance of controlling JD, Defra, in conjunction with its sister departments in Scotland, Wales and NI, has launched an advisory leaflet for dairy farmers, detailing measures to control JD.

Although the Advisory Committee on the Microbiological Safety of Food has not altered its advice to the Food Standards Agency in relation to the consumption of milk and dairy products, the matter is under ongoing surveillance. It should be recognised, also, that the threat is not limited to possible medical evidence of a link between MAP and CD. Supermarkets have asked suppliers for information on the JD status of their herds, and maintain an interest in the whole area of MAP. And if other countries are taking steps to deal with MAP at dairy herd level, it is a reasonable assumption that at some stage they will want to use their activities to gain competitive advantage in the market place.

Therefore, if the NI dairy industry is not to be disadvantaged, it needs a strategy for dealing with this issue.



Protection of the NI powder market is of significant importance to dairy farmers' income; and development of a related strategic option for dealing with the issue of MAP in milk and dairy products also has significant financial implications for dairy farmers.