Is there a link between
Johne's disease and Crohn's
disease in humans?
If there is a link between Johne's
disease (JD) and Crohn's disease
(CD), it hasn't been proven, says
Johne's disease expert Mike Collins,
DVM, PhD, University of Wisconsin.
What has been scientifically proven
about the relationship between these
two diseases, according to Collins, is:
n Mycobacterium avium subspecies
paratuberculosis (MAP) causes JD.
n MAP contaminates food of animalorigin;
primarily milk and meat.
n JD resembles Crohn's disease in pathology,
epidemiology and clinical signs.
n MAP is consistently found in
people with CD.
"The only remaining question is
whether MAP causes CD or whether
CD patients merely become infected
with MAP after they have their disease,"
Collins says.
A report issued in August by the
American Academy for Microbiology
highlighted that group's concern that
MAP may cause Crohn's disease. The
report states that "people with Crohn's
disease are seven-fold more likely to
have in their gut tissues the bacterium
that causes a digestive-tract disease in
cattle called Johne's Disease. The role
this bacterium may or may not play in
causing CD is a top research priority."
The report — Mycobacterium avium
paratuberculosis: Incidental Human
Pathogen or Public Health Threat? —
summarizes conclusions and recommendations
from a colloquium convened
by the American Academy of Microbiology
in June 2007. That conference
brought together experts in microbiology,
medicine, veterinary pathology,
epidemiology, infectious diseases
and food safety.
A full copy of the report can be
found at: http://www.asm.org/Academy/
index.asp?bid=60057.
Collins says this report doesn't come
down with a firm conclusion saying,
"yes" or "no," but, "it brings a lot of attention
to the issue." Bovine Veterinarian