University of Wisconsin–Madison

Potential Cost of MAP in Milk

L. Chiu and colleagues from Cornell University and the University of Illinois published a research article exploring the societal costs of MAP in the milk supply and a link of MAP to Crohn’s disease. Their work was published in the International Journal of Food System Dynamics [Open Access].


Welfare costs of a potential food shock were estimated by disseminating information to milk drinkers on the prevalence of Mycobacterium avium sub. paratuberculosis (MAP) in the U.S. milk supply, its potential linkage to Crohn’s disease in humans, and subsequent government intervention to minimize MAP in the milk supply. We found that 19.6% of milk consumers exposed to MAP information would stop milk consumption at current market prices, and that only 5% of those would return to their original milk consumption levels after the government intervention. Societal costs of the food shock after the intervention were estimated at $18.2 billion.


A similar study by H. Groenendaal and Zagmutt was published in the Journal of Dairy Science in 2008. This article, not cited by Chiu, explored three scenarios developed based on the effectiveness of possible risk-mitigation strategies. As reported in their publication, “in the first scenario, it was assumed that an effective strategy exists; therefore, a negligible demand decrease in the consumption of dairy products was expected. In the second scenario, it was assumed that new risk mitigation would need to be implemented to minimize the health hazard for humans. In this case, a small milk demand decrease was expected, but larger demand decreases were also possible. The third scenario assumed that no fully effective risk mitigation was available, and this resulted in a considerable demand decrease and a potential reduction in milk supply as a result of regulatory measures. A milk demand reduction of 1 or 5% resulted in a reduction in consumer surplus of $600 million and $2.9 billion, and a reduction in dairy farm income of $270 million and $1.3 billion, respectively. A decrease in milk supply would cause a slight increase in total losses, but would cause the greatest losses to test-positive dairy farms. Given the current scientific knowledge about MAP and CD, we conclude that if a link were established, it is most likely that the first or second scenario would occur. Thus, consumer response and economic consequences to the discovery of such a link are expected to be limited, but could be large if the consumer’s perception of risk is large or if risk-mitigation strategies were ineffective.


Prevention pays! Dairy producers and processors should work to limit the potential impact of MAP on consumer acceptance of dairy products. The necessary diagnostic tools and knowledge on how to control MAP infections in dairy cattle are available. Some countries have implemented national control programs to help avert negative consumer reactions should medial science accept that MAP is a zoonotic pathogen. Actions to control MAP in dairy cattle can protect consumer confidence while also improving farm profitability and animal health and welfare.