Johne's disease

Alert

Johne's disease is category 1 restricted matter.

Under Queensland legislation, if you suspect the presence of this disease in any species of animal, you must report it to Biosecurity Queensland on 13 25 23 or contact the Emergency Disease Watch Hotline on 1800 675 888.

The national scoring framework for assessing and managing JD in dairy cattle has been amended. There are options for Queensland producers for transitional period until 30 September 2019.

Johne's disease (JD) is a serious disease of cattle, sheep, goats, alpaca, llama, camels and deer.

There are several strains of the organism:

  • cattle (also 'C' or bovine) strain, which is found in Australia – mainly in dairy cattle, but also in beef cattle, alpaca, goats, deer and camels
  • sheep (also 'S' or ovine) strain, which is found in Australia – mainly in sheep and goats, but increasingly in beef cattle which have co-grazed with infected sheep in southern Australia
  • bison (also 'B') strain, which has been found in a small number of beef cattle cases in Queensland.

Cause

Mycobacterium avium paratuberculosis

Other names

  • Paratuberculosis
  • In cattle: bovine Johne’s disease (BJD)
  • In sheep: ovine Johne’s disease (OJD)
  • JD

Distribution

The disease occurs worldwide. Australia has relatively little JD compared with most developed agricultural countries. It is more commonly found in southern states of Australia, and particularly in dairy cattle herds and in sheep flocks in high rainfall areas.

Life cycle

The bacteria lives and multiplies in the small intestine and lymph nodes and is shed in the faeces. It is very slow-growing.

JD has a long incubation period. Clinical disease is not usually seen until at least 2 years after infection (except in deer, which can show disease much earlier).

Affected animals

  • cattle
  • buffalo
  • sheep
  • goats
  • alpaca
  • llama
  • camels
  • deer

Symptoms

Clinical signs are:

  • a gradual loss of weight despite a normal, or increased, appetite
  • diarrhoea develops in cattle, but not routinely in sheep
  • 'bottle-jaw' is also seen in cattle.

Clinical signs are typically induced by stress, especially nutritional stress during lactation for cows and ewes. In sheep, clinical JD typically shows as a tail of ewes that fail to recover body condition after weaning and then waste away.

Animals showing clinical signs due to JD will inevitably die.

Impacts

The productivity impacts of JD vary according to stress and husbandry systems. Extensively grazed beef herds typically show negligible clinical JD, except in drought or other stress. Dairy cattle that are under greater nutritional stress and potentially exposed to high doses of infection, have a higher prevalence of infection and higher incidence of disease. The incidence of clinical disease in sheep can be marked, especially under conditions of cell grazing.

It has been speculated that the mycobacterium responsible for JD in animals is linked to Crohn's disease in people. Considerable research has been conducted and an association between the conditions remains to be proven.

JD risk status is a common eligibility criterion for export trade and currently for trade to NT and WA. Producers whose market success may be affected by JD should protect against entry of infection and manage it to prevent further incidence of disease.

How it is spread

The bacteria may be found in the colostrum, milk and faeces of infected animals. Apparently healthy carrier animals with no signs of disease as well as clinical cases can shed the organism.

Bacteria are transmitted from an infected female animal to its offspring in colostrum or milk, but mainly from faecal contamination of the teats, udder and environment. Infected bulls, rams and other adult males can also spread infection in their faeces.  Ingestion of contaminated pasture, food, milk, or water can then cause infection.

Bacteria survive in faecal material and on pastures where other animals can pick up the infection. In wet conditions, bacteria can survive in the environment for up to 1 year.

Risk period

Young animals are infected either when suckling their dam or grazing contaminated pasture.

Older animals, especially cattle, may be less susceptible than younger animals.

Monitoring and action

Find out more about your obligations to manage JD (PDF, 128KB), especially when buying and selling livestock.

Ongoing monitoring

Monitor animals and report any suspicious signs of diarrhoea or wasting. Diagnostic tests are conducted free-of-charge at the Biosecurity Queensland veterinary laboratory.

Testing

Testing is complex and can take 12 weeks or longer if complications arise. Blood and faecal samples are collected from live animals to test for JD.

Faecal culture or PCR testing provides a reliable result but the culture test takes up to 3 months to complete.

The blood test is rapid but is suitable mostly as a herd test. Interpretation of an individual animal test may be difficult because false positives and negatives can occur.

Tissue samples of the small intestine and lymph nodes can be collected at necropsy for histological examination and culture.

Control

There is no treatment for JD, and animals showing clinical signs inevitably die. A vaccine is available to aid protection against ovine Johne's disease (OJD) in sheep and goats, and bovine Johnes disease in cattle.

Responsibility for JD in Queensland shifted in 2016 from a government program of regulatory prevention and control to property-based industry management by producers. This provides flexibility for individuals to responsibly manage JD risks according to the needs of themselves and their market chain. The national industry bodies for beef, dairy, sheep, goat and alpaca have tools and frameworks in place to assist producers to assess and manage JD risks, accessed through Animal Health Australia.

The first step to assessing and managing farm JD risks is to write up a farm biosecurity plan. To protect against JD being brought onto a property, producers should always insist on examining a national health statement for JD risk before any livestock are bought or allowed to enter.

Suspicion or confirmation of JD remains notifiable. Under the new approach, Biosecurity Queensland does not restrict livestock movement or quarantine a property if JD is suspected or confirmed, but will direct producers to information that will assist them in understanding and managing Johne’s disease risk.

Any person who owns or deals with animals that are suspected or confirmed of being infected with JD must take practical and reasonable steps to contain the infection and reduce the risk of spreading the disease further.

Producers should work with their local veterinarian to manage and meet their obligation regarding Johne’s disease.

Find out more about your obligations to manage JD (PDF, 128KB), especially when buying and selling livestock. This guideline is a simplified fact sheet.

Further information