Identifying Johne's disease with accuracy

Published on: Apr 1, 2013

Detecting the costly, contagious Johne's disease in cattle is now easier thanks to researchers with the U.S. Department of Agriculture's Agricultural Research Service (ARS).

Johne's disease, also known as paratuberculosis, is estimated to cost the U.S. dairy industry more than $220 million each year, ARS said. It also affects sheep, goats, deer and other animals, causing diarrhea, reduced feed intake, weight loss and sometimes death.

ARS microbiologist John Bannantine and his colleagues at the National Animal Disease Center in Ames, Iowa, discovered an antibody that's 100% specific in detecting Johne's disease. This is the first time a specific antibody that binds only to Mycobacterium avium subspecies paratuberculosis (MAP), the pathogen that causes the disease, has been discovered. A patent has been awarded to scientists for the antibody, which could greatly benefit the improvement of diagnostic tests that confirm the presence of MAP.

Previous efforts to detect Johne's disease were hindered because all antibodies used to identify MAP strains also reacted to environmental mycobacteria, according to Bannantine, who works in NADC's Infectious Bacterial Diseases Research Unit. Some of those antibodies also reacted to the disease pathogen responsible for bovine tuberculosis (TB) and caused false-positive results.