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ARCHIVE: Johne's Disease in cattle

Johne‘s disease is an infectious wasting condition of cattle and other ruminants caused by Mycobacterium avium subspecies paratuberculosis (commonly known as Map). It is genetically related to the organism that causes tuberculosis, but does not itself cause tuberculosis in either humans or animals . The disease progressively damages the intestines of affected animals, and in cattle this results in profuse and persistent diarrhoea, severe weight loss, loss of condition and infertility. Affected animals eventually and inevitably die. In dairy herds, the presence of Johne’s disease will significantly reduce milk yields well before other signs of the disease can be found.

Although not a notifiable disease in Great Britain, Johne’s disease is notifiable in Northern Ireland. It has a world-wide distribution.

You can download information on Johne’s Disease from this website or call the Defra Publications line on 0845 955 6000 quoting publication number PB9990.

Why should farmers care about Johne’s disease?

The disease can have a significant financial impact on herds through loss of output and early culling. It has been suggested that this organism may also be a possible cause of Crohn’s Disease in humans. Such a causal link between the two conditions has yet to be proved or disproved, however the Government is taking a precautionary approach in this area. A possible route to infection in humans could be through consumption of milk containing Map.

Control and prevention of Johne’s disease makes sound long term sense for three reasons:

1. To reduce or prevent your production losses and income that result from this disease;

2. to increase the value of your breeding stock if your herd is certified as free of the disease and

3. to reduce the level of Map in milk and the environment.

The Food Standards Agency has published a strategy for reducing the levels of Map in milk. The strategy includes the following components:

How is Map spread?

Diseased animals in general pass large numbers of Map in their faeces (dung). A single diseased animal can therefore pose a high risk to susceptible animals and in particular to the young calves in the herd. Diseased animals may also excrete Map in milk and colostrum. While cattle remain susceptible to infection throughout life, they are at their most vulnerable in the first few months of life. Calves may be infected in the womb but are more commonly infected through:

  • drinking contaminated milk or colostrum;
  • ingesting dung that may be present on unclean teats;
  • contaminated feed; and
  • contaminated environment or water supplies.

How can you spot Johne’s disease?

Map is a slow growing organism.  Animals are generally infected early in life but signs of the disease are rarely seen before two to three years of age. Generally, there is a period of reduced milk output or fertility well before the animals begin to show signs of advanced disease. These signs include persistent and profuse diarrhoea and significant weight loss, and are seen most commonly in animals at three to five years of age. After initial infection at a young age, a prolonged period (lasting in some cases for several years), follows when there may be no detectable antibody and no shedding of the organism in the animal’s faeces. As the infection progresses to the stage of clinical disease, it becomes easier to detect the organism in the faeces and to detect antibodies in the blood. The older the animal the more likely the available diagnostic tests (blood test and faecal culture test) are to find the infection. It is very difficult to detect an infected animal, by any of the currently available tests, before it is two years of age.

Page last modified: December 10, 2009