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Johne's Disease

Johne's disease is a chronic enteritis of ruminants caused by M. paratuberculosis. It is greatly under-diagnosed in sheep according to NADIS.

In many infected flocks the annual ewe mortality rate from Johne's disease can be between five and 10 per cent.

This bacteria embeds itself in the wall of the lower part of the small intestine known as the ileum.

As an immune response, infected tissues attempt to regenerate healthy tissue which leads to visible thickening of the intestines.

This prevents nutrient absorption, resulting in weight loss.

Late in the infection, antibody production by the animal can be found in serum of animals and is an indicator that clinical signs of disease and death from the infection will soon follow.

M. paratuberculosis grows and multiplies inside the cells of an animal's immunie system and are excreted in the faeces, and to a lesser extent in milk and saliva.

When the microbe is excreted, it can contaminate the soil or water.

The primary cause of the spread of Johne's disease is contact with the faeces or saliva of an infected animal.

Because of the slow, progressive nature of the infection, signs of Johne's disease may not show up until years after initial infection. When they finally do occur, the signs are long-lasting diarrhoea and weight loss although this does not show itself in the same way it does with cattle.

For more information on Johne's disease, diagnosis, treatment and prevention click here.

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