Johne’s disease is the clinical syndrome of end-stage infection with the bacteria Mycobacterium avium paratuberculosis or 'MAP' for short.
Whilst many infected cows never go on to develop the classic signs of extreme weight loss, infected cows are very likely to have reduced performance and are very likely to shed bacteria in dung and milk. Shedding of bacteria poses a huge infection risk to young animals and therefore segregation of infected cows around calving is an essential step for reducing prevalence.

Milk ELISA tests offer a rapid, cost effective and valuable method of monitoring the herd prevalence of MAP infection, allowing timely and evidence-based implementation of control strategies. Individual cow milk ELISA testing allows you to screen cows for antibodies to infection and highlight positive cows (and therefore those likely to be infected) and manage them differently to break the cycle of transmission.

Johnes plate blob

Download our Johne's disease brochure
Group 3

QMMS categorises the milk MAP ELISA results as follows:

Interpreting your results:

Currently negative
(all tests negative or previously tested positive once but have subsequently tested negative on three consecutive occasions).

Uncertain
(antibody test is very close to threshold and/or cows that have previously tested positive but have since tested negative);

Provisionally positive
(the latest milk ELISA test is positive);

Positive
(two ELISA test positives out of the last three tests) – these cows are more likely to be infected and are not re-classified once they are categorised as positive, regardless of any subsequent ELISA test results;

As milk ELISA testing will result in some apparent positive results being ‘false’ positives, particularly in low prevalence herds that test relatively frequently, culling a cow based on one positive test result is not recommended. At least two positive tests should be obtained before making definitive decisions as this will increase the certainty that the cow is infected.

The aim of milk ELISA testing should always be to risk manage those cows that are more likely to be infected and segregate these cows from calving areas and the colostrum pool. In reality this means that any cows that are currently listed as ‘positive’, ‘provisionally positive’ or ‘uncertain’ should be identified and managed differently at drying-off in conjunction with advice from your veterinary surgeon. Research carried out by QMMS and the University of Nottingham has recently led to the development of a Johne’s “Pattern Analysis Tool” which enables detection of “Hidden High Risk Cows”, allowing them to be managed to minimise spread of disease. This is particularly useful in low prevalence herds. Find out more at JPAT News 

As with our milk recording and bacteriology services, the MAP ELISA service is backed by Royal College of Veterinary Surgeons Recognised specialist advice, helping with interpretation of results and enabling a unique ‘joined-up’ approach to the control of Johne’s disease in your herd.

The suggested QMMS protocol has a strong evidence-base and outlines our interpretation of the latest research evidence on the application of milk MAP ELISA’s and may therefore change as more research in this area is published. 

Full integration with on farm software is available in conjunction with SUM-IT Computer Systems. In the absence of compatible on farm software your results will be emailed as .pdf files reporting both your current and historic results.

FAQs

Why Test for Johne’s Disease?

The impact of Johne’s disease on dairy herd profitability has come to the fore in recent years and it is now understood that this disease can be having a significant impact in some herds. Effective management of the disease is best achieved with a targeted testing and management regime. QMMS offers a cost effective and evidence based Johne’s disease testing service and is the only service in the UK which is fully integrated with on farm software.

Do I have to milk record with QMMS to use the MAP ELISA service?

No - dairy herds not already milk recording with QMMS can be sent a kit – please call 01749 871171 or email enquiries@qmms.co.uk. Farms that use QMMS for milk recording can use samples collected for routine milk recording purposes.

Do I have to collect milk from all the cows every time I sample?

Initially, all cows currently in milk as well as the bulk tank are sampled and tested for antibodies toMAP to give an estimate of the herd prevalence. The herd screen is then repeated so that all cows are tested at least three times, three months apart; this allows cows to be initially classified as ‘positive’, ‘uncertain’ and ‘currently negative’. Cows that test ‘positive’ on at least 2 of three occasions are not subsequently re-tested but are labelled ‘positive’. Cows that test ‘currently negative’ and are in lactation 3 are retested every 6 months; those that are in lactation 4 and above are re-tested every 12 months. This is because studies have shown that the peak prevalence of seroconversion is in cows aged between 2 and 4 years.

Do I have to cull a cow if she is labelled positive from one sample?

No, a cow shouldn’t be culled on the basis of a single test, primarily due to the inherent sensitivity and specificity of the testing process. If the herd policy is to aggressively pursue the disease, then additional testing such as a faecal PCR test to confirm the disease status is recommended. In other cases the cow should be managed as if positive until the results of subsequent tests are known.

Can I sample cows for a MAP ELISA screen if I have recently had a TB test?

Concurrent testing for bovine tuberculosis (bTB) using purified protein derivative tuberculin has the potential to introduce false positives, ie cause the milk Johne’s ELISA test specificity to fall. We therefore recommend herds that have had a bTB test in the last 60 days avoid using milk samples for MAP ELISA testing.

Do I need to sort all my samples into cow number order?

No, we actually discourage this practice as it leads to the potential introduction of systematic errors into the process.

How do samples get to the laboratory?

Once you phone us to confirm when the samples will be ready, we will arrange courier collection; samples are delivered to us the next working day. You can of course deliver your own samples (and save on the courier costs) if you so wish. For up to 60 samples it may be cheaper to post the samples than to use a courier.

Do you provide paper reports?

Our service is designed to be paperless with all data traveling electronically. However, paper reports can be provided if required (at a small additional cost).

How do I pay?

You only pay for the tests performed, no more - no less. We invoice monthly and offer substantial regular testing discounts linked to prompt payment.