JOHNES

· FVS provide AHWNI advisors – assessment mandatory for red tractor scheme

· Mention Johne’s occurs in SHEEP and we can also help detect this – VACCINE AVAILABLE IN UK

Johne’s (pronounced “Yo-nees”) is a disease caused by a bacterium called Mycobacterium
Avian subspecies Paratuberculosis (MAP for short!). This is a chronic, contagious disease affecting ruminants. It is thought that up to 30% of all herds in the UK are infected with Johne’s, causing a huge financial loss to some farmers.

Initially the bacteria live in the gut of infected cattle where they grow and slowly cause damage. Once the disease progresses, the bacteria spread to other parts of the body including the udder, womb and lymph nodes.

Importantly, Map does not always infect an animal after exposure. When infection does occur, the clinical signs of disease do not occur immediately.

Signs of Johne’s disease are typically seen in animals that are between 3 and 5 years old but can occasionally be seen in animals that are younger than two years of age.

The typical signs include:

weight-loss despite a good appetite
scour (not bloody)
soft swelling of the jaw (bottle jaw) or brisket
death

As the animal gets older, the signs become more obvious. An infected animal may also suffer reduced production, reduced fertility performance and increased susceptibility to other disease before the obvious signs occur.

The challenge of controlling Johne’s disease

Control of Johne’s is not without its challenges because of a number of factors.

The disease has a long incubation period and there is a lengthy delay (most often between 2 and 4 years) in antibody production in response to infection. So an animal may be infected but because the body is responding slowly to that infection, there may be too few antibodies for the test to detect.
Frustratingly, the antibody does not afford any actual protection from the disease.
When infected animals start shedding the MAP bacteria in their faeces, they become ‘infectious’. However, this shedding can be intermittent, and can actually occur before antibodies can be detected by the test. Consequently, the blood and faecal tests are not as sensitive at detecting ‘positive Johne’s’ animals as for some other diseases.