A possible connection between Johne’s disease in cattle and Crohn’s disease in humans remains unproven.
Johne’s disease is caused by the bacteria mycobacterium paratuberculosis (MAP) that affects the intestines of cattle, sheep and goats. The animals cannot absorb nutrients properly, develop diarrhea and slowly waste away.
Finding a connection between the bacterium in animals and people is the work of Herman Barkema, an epidemiologist with the University of Calgary’s veterinary school who has a special interest in Johne’s disease.
“The role of MAP in Crohn’s is possible but not proven,” he said at a national seminar on Johne’s disease held in Calgary this summer. “There are other pathways to Crohn’s disease.”
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Considerable inflammatory bowel disease research is underway and scientists have learned plenty about the condition but remain unsure of its causes. There could a genetic susceptibility, an autoimmune disorder or a bacterial infection.
In the last five years researchers have decided people with a particular genetic mutation are more likely to get Crohn’s disease.
Crohn’s, which affects the terminal ileum, tends to affect those in the 15 to 25 age group. People between the ages of 55 and 65 tend to suffer more often from ulcerative colitis, which affects the rectum.
The incidence of Crohn’s appears to be increasing.
“There are 40 times more people with Crohn’s disease at this moment that have been identified since the 1930s,” Barkema said.
Symptoms include chronic, urgent diarrhea, nausea, weight loss, lack of energy and no successful treatment. Tests are painful and patients often require intestinal surgery.
There have been suggestions the infection could be spread from cattle to people through milk. One study showed 15 percent of Ontario milk tested positive for the bacteria DNA but it was likely dead. It is not known if the killed pathogen can cause disease.
