18 December 2006

2 minute read

North America

Johne's (pronounced yo-nees) disease is an infectious bacterial disease affecting the intestinal tract of cattle.

The cause is a bacterium called Mycobacterium paratuberculosis, which invades the small intestine. The infection causes thickening of the intestinal lining, which leads to poor nutrient absorption. The most common source of Johne's infection is manure from infected cattle. The bacteria can survive over a year outside the animal, and other animals ingest it, becoming sick. Many cows in the later stages of the disease also transmit Johne's microbes to calves, via colostrum and milk.

The fetus can also be infected in the womb, if the dam is in the later stages of the disease. On farms where Johne's disease has not been found, it's been very important to keep out infected animals and develop a Johne's prevention management plan. Dairy and beef herds that have the disease have more of a challenge to overcome.

Johne's disease has been difficult to diagnose until the clinical disease is expressed later in life. By that time, the sick animals have spread the infection to many other animals via feces. "Imagine a thief sneaking into your herd and subtly robbing economic returns for years before you even suspect a problem. Once discovered, imagine having to spend several more years to rid yourself of the culprit," is how Johne's is described in a handbook from the National Cattlemen's Beef Association.

Source: Billings Gazette