Johne’s disease is a bacterial infection of the intestine which primarily affects domesticated ruminant animals (cattle, deer, sheep, goats and alpaca). The infection causes the intestinal tissues to become thickened and inflamed resulting in reduced uptake of nutrients. The disease is chronic, infectious and progressive and results in decreased productivity, wasting and ultimately death. Johne’s disease is sometimes also referred to as paratuberculosis.

Johne’s disease is a straightforward bacterial infection caused by the bacterium Mycobacterium avium subspecies paratuberculosis, also known as MAP. Progression of the disease may be triggered by additional physiological stressors such as poor nutrition, parasitism, calving, weaning, lactation, transportation, social mixing or adverse environmental conditions.

• Overt signs of early stage clinical disease may be subtle, with mild weight loss and/or reduced milk yield.
• Infected animals may lose weight or be unable to gain weight despite good appetite.
• More severe disease will often, but not always, manifest with profuse and chronic, watery diarrhoea which does not respond to treatment and which may be intermittent. This is less common in sheep and goats. As the disease progresses, animals become progressively more emaciated and dehydrated.
• Periods of remission may be seen in which affected animals appear to improve in condition.

Recent estimates suggest that as many as 60% of NZ dairy herds may now harbour some MAP infection, with 10% of herds experiencing clinical disease on farm. Similarly, 60% of deer herds, 31% of beef herds and 68% of sheep flocks are estimated to be exposed to MAP infection, although within herd incidence of clinical disease is much lower.

In addition to animal health and welfare concerns, Johne’s disease is a production limiting disease which impacts upon growth, milk yield and fertility and imposes capital losses due to premature culling or death. On top of these production losses, the presence of Johne’s disease on an affected property causes significant indirect costs through constraints on management and restrictions on stock movements as well as causing tangible distress to herd owners. Of growing concern also is a reported association between MAP bacteria in dairy derived foodstuffs such as infant milk formula and Crohn’s disease in humans which has led many countries to establish national control programmes.

No. Animals with Johne’s disease don’t respond to any form of treatment. There is no cure and animals should be managed as soon as the diagnosis is confirmed.

The best treatment is a good Johne’s Management Plan.  The Paralisa™ test measures the animal’s immune response to the MAP bacteria which leads to Johne’s Disease.  Animals which have mounted an immune response may be at different stages of being AFFECTED by the disease.  These animals should be marked as Johne’s (via an ear tag, or in your database) and monitored for changes in production or body condition.

Colostrum from Johne’s animals should not be given to calves, and calves from Johne’s dams should be managed.  Always keep a close watch on Johne’s positive animals that are still in your herd during any stress event, such as calving, moving, or changes in environment or feed availability.

No. Animals with Johne’s disease don’t respond to any form of treatment. There is no cure.

Vaccination may be an option for some species although currently available vaccines may cause false positive reactions with the TB skin test and are not commonly used in NZ cattle or deer herds. While vaccination does not prevent infection or disease, it may lessen or delay the onset of clinical disease and reduce overall shedding. We advise speaking with your veterinary practitioner.

Johne’s disease is primarily a condition of farmed ruminant species (cattle, deer, sheep, goats and alpaca). MAP infection (as distinct from Johne’s disease) has been observed in diverse species including rabbits, possums, hares, hedgehogs, stoats, cats and even ducks.

Although visible indicators of late stage disease typically include diarrhoea and progressive weight loss despite good appetite, these physical signs are also associated with a number of other conditions and should not be considered uniquely diagnostic for Johne’s. In addition, animals exhibiting physical symptoms arising from Johne’s disease will only be the tip of the iceberg and for every clinically affected animal, a minimum of 25 other animals are likely to be infected but asymptomatic. The only way to know for sure is through laboratory testing. Cull animals should have their Johne’s status confirmed.

Serology (ETB/ParalisaTM)

• Blood (serum or plasma tubes; min. 3ml).
• While refrigeration is desirable it is not essential; please protect samples from extremes of heat or cold.
• Do not freeze.

Faecal PCR

• 5-10g of dung (about a tablespoon) from each individual, cleanly pottled and labelled, is all we require (while we can work with less, this is what we ask folks to aim for…).
• The most important thing to remember when collecting and sending samples is to avoid any chance of cross-contaminating the samples. Tightly closed, plastic sample pottles work well (we can forward these on request; plastic ziplock bags or similar are not suitable have been known to fail quite catastrophically in the past…).
• Dung samples freshly deposited on the ground are perfectly fine also – as long they can be unambiguously linked to their originator and land on an otherwise clean surface.
• Always be sure to change gloves between each individual.
• If sample pooling is requested, send individual samples as we will carry out the pooling here; that way we can easily retest individuals from positive pools as required. If a pool is positive, we will contact you concerning your preference for individual sample re-testing.
• Send the samples in as soon as possible (but know also that they are quite all right for several days at ambient temperature).
• Send the samples, preferably by overnight courier, to –
  Disease Research Ltd,
  Invermay Agricultural Centre,
  176 Puddle Alley,
  Mosgiel 9053.
• A heads-up phone call (03 4894832) or email (drl@drl.net.nz) to let us know the samples are coming is always appreciated.

If you need assistance collecting samples, contact your vet, or, you can also contact our partner, AsureQuality, to arrange sample collection:

Herd Health Management – Livestock Management – AsureQuality

Johne’s disease is usually ‘bought and paid for’ by introducing infected replacement animals into an otherwise clean, MAP-free environment. Avoid introducing MAP to your property by observing good biosecurity practices; operate a closed herd/flock or, failing that, only purchase from sellers with a verifiable, JD test negative history and test any replacements brought onto the property before they arrive. Quarantine new stock and ensure boundary fencing is secure. Avoid cograzing young and adult stock; a top priority should always be to reduce/eliminate calf and heifer exposure to adult faecal matter. Don’t allow replacement heifers to share grazing with adults or follow adult stock in a rotation.

Most commonly through the purchase and introduction of infected stock. Johne’s disease is an infection of the intestine and the single greatest risk factor for disease transmission is contact with faecal material from infectious animals; anywhere that may be contaminated by faecal material from unknown animals such as stock trucks or shared water schemes should be considered potentially contaminated with MAP. Airborne transmission is not generally considered to be a risk factor for MAP although the bacteria maybe become aerosolised if effluent is sprayed onto nearby paddocks.

Johne’s can be successfully controlled through careful planning and management, supported by test informed culling of high shedding animals and expert advice. Unlike tuberculosis (caused by the closely related Mycobacterium bovis) complete eradication of Johne’s disease at any level (on farm, regionally or nationally) is not considered feasible, achievable or likely and control efforts are instead focused upon cost-effectively managing clinical disease and associated production losses out of the herd.

The single greatest source of infectious MAP bacteria is an actively shedding, Johne’s disease affected animal.

Absolutely. In addition to animal health and welfare concerns, Johne’s disease is a production limiting disease which impacts upon growth, milk yield and fertility and imposes capital losses due to premature culling or death. On top of these production losses, the presence of Johne’s disease on an affected property causes significant indirect costs through constraints on management and restrictions on stock movements. Many studies have found MAP infection to be associated with a significant reduction in milk production in dairy cows. Our experience suggests that daily milk solids production is 4% less for infected cows, 6% less for moderately diseased cows and 12% heavily diseased cows shedding large numbers of bacteria, compared with uninfected cows.

MAP bacteria can only multiply once inside the immune cells of a suitable host but following shedding may lie dormant outside of the animal host for long periods on pasture. Studies suggest that, in a temperate climate such as in NZ, viable MAP bacteria can persist under moist conditions in the environment in soil, dung and water for as long as 18 months. Conditions which promote killing of environmental MAP bacteria include desiccation and UV exposure through exposure to sunlight.