Johne’s disease, associated with the MAP bacteria, causes intestinal infection leading to direct financial loss from culling, decreased milk production, mortality, and reproductive losses.

There are public health concerns because MAP in milk may survive pasteurization and has been associated with human Crohn's disease. 

MAP is able to survive, reside, and multiply in immune cells present in bowel and milk. If fact, cell-associated MAP may  be more infectious than the free form of the bacteria. Current diagnostic tests focus on pathogen identification, by culture or molecular methods, typically in feces or identification of antibodies in serum or milk with an enzyme-linked immunosorbent assay (ELISA). New diagnostic methods focus on identification of specific proteins that are associated with cell infection that are produced early and continuously in the infection process.

It is important to understand the shedding of the MAP bacteria, particularly around calving because of the susceptibility of the newborn calf to infection.  Additionally, a good diagnostic tool for identification of contaminated colostrums would be highly advantageous in Johne’s control.

MQM will be using data from a companion project to identify 30 MAP infected cows to better document monthly shedding patterns. Understanding of these shedding patterns during the lactation will optimize diagnostic and control protocols.  Using the above 30 cows and an additional 60 cows with high milk ELISA, they will develop methodologies for MAP organism or protein marker detection in fresh cows. Development of these testing systems could lead to farm-based colostrum testing as part of a control program.