Johne’s Disease (MAP)

Item No.  864

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Johne’s disease or paratuberculosis is caused by Mycobacterium avium subspecies paratuberculosis (MAP). The disease is characterized by chronic, debilitating enteric inflammation in ruminants and causes significant economic losses to livestock industries worldwide. Eradication efforts have been hampered by the fact that it is very difficult to detect the presence of MAP during early infection.

Progression of the disease is usually very slow so the subclinical early phase of the disease can last for years. During this time, however, MAP continues to be shed in the fecal matter of the animal and can therefore readily contaminate the environment. Nursing young stock is at very high risk to become infected, either through contaminated fecal matter on the teats or through MAP being shed in the milk.

During the early phases of the disease, production losses include decreased milk production, decreased fertility, and higher premature cull rates. The most prominent signs of Johne’s Disease (incurable diarrhea and weight loss up to emaciation and death) do not occur until later in the progress of the disease. In that stage, more MAP bacteria are being shed through the feces into the environment and infected animals start to develop antibodies in the blood to fight the bacteria.

NEOGEN® offers two different tests to detect the presence of MAP on the premises:

  1. Detection of MAP. This test uses the polymerase chain reaction (PCR) methodology. Detection of MAP can be done on the individual animal's fecal sample or a fecal composite sample from the environment when MAP is suspected. The PCR method is currently considered the most sensitive detection method available that can achieve a diagnostic sensitivity up to 96%. The PCR method is much faster than the alternative detection method by culture.

  2. Detection of the antibodies against MAP. This test is an ELISA test (Enzyme-linked immunosorbent assay). Detection of the presence of antibodies means that the animal has been exposed to MAP for a while. Usually, the more advanced the disease is, the more readily and confidently the antibodies can be detected. The ELISA test is a very useful and affordable screening tool to assess the MAP antibody status in a herd. Once antibody titers have been found, either in the blood or in the milk, follow up testing by PCR is recommended to identify the individual animals that are actually shedding MAP.

Both the MAP detection and the antibody detection test that Neogen offers are certified by the National Veterinary Services Laboratory (NVSL), the federal reference laboratory for animal disease testing. Since only about 10% of infected animals progress to the most advanced stages of the disease, with heavy MAP shedding and high antibody levels, it can be assumed that for each animal that MAP was detected in, there are many more animals on the premises that are already subclinically infected but do not show any overt signs yet.

The NVSL check test is administered as part of the National Johne’s Disease Control Program. Individual states may have a voluntary Johne’s Disease control programs, with some able to subsidize the testing. A very valuable part of these programs are the "test negative herds." This program includes various status levels, which represent levels of certainty that the herd is free of Johne’s Disease. While this is not a guarantee, the highest status comes with a high degree of certainty and represents a significant addition of value to the herd.

Specifications
Species Bovine, Ovine, Goat
Submission Information

Acceptable sample types:

For MAP detection by PCR
The sample type needed for testing is fecal matter. Several grams of sample are requested, equivalent to about half a cup. If samples are very liquid, make sure to include the liquid. Leak-proof sample containers are required. Wear gloves for sample collection. If possible, collect samples directly from the animal's rectum.

If individual animal testing is desired, make sure gloves are changed between samplings so cross-contamination is minimized.

The Neogen laboratory is certified to pool five samples into one test sample. If a pool of animals is to be tested, collect the fecal samples from each animal into separate containers and request the samples to be pooled by the laboratory (on the submission form). Do not pool samples on the farm!

If environmental sampling is desired, collect fecal material from up to five areas most heavily travelled by the animals. Collect about equal amounts of fecal material per sampling site, either into one large container and indicate the sample is pre-pooled, or collect into several small containers and request pooling by the laboratory (on the submission form).

For detection of antibodies
The sample type needed is serum, plasma, or milk. Whole blood (about 2 ml) can be collected in a red top or red/gray top tube, or a purple top tube. Make sure tubes are labeled with the animal IDs and the consecutive number.

Requirements for shipping:

In order to maintain optimal sample quality for optimal test performance, it is recommended to send the samples by next day air in a Styrofoam box with an ice pack. Avoid freezing the samples.

Turnaround Time Results are usually available the next day after samples have arrived in the lab, both for PCR testing and ELISA testing.

Training

Our customers’ success is our shared success. Our customer service teams are ready to assist you and your team on our solutions, so you can rest easy knowing sampling procedures are performed properly and yield accurate results. (Link to Global GN contact page)


Support

Is there a best time for collecting samples?
The likelihood of MAP shedding increases at times when infected animals are stressed. For cows, this occurs regularly during the late stages of pregnancy and during freshening. Testing of cows by fecal PCR at those times will enhance the ability to find MAP if it is present. Remember to include bulls in the testing. Even though they do not get stressed as predictably as cows, their breeding activities can be stressful as well, increasing the likelihood of finding MAP if it is present.

Can the PCR test tell me how much MAP is present?
Yes, to some degree. The strength of the positive signal is proportional to the number of MAP present, so the stronger the signal, the more MAP in the sample. This is how the animals shedding the highest numbers of MAP can be identified.

What other test methods for the diagnosis of Johne’s disease are there?
There is currently only one alternative MAP detection method available. That method is to try to selectively culture the MAP bacteria. Since MAP bacteria are very slow growing organisms, the culture can take weeks to conduct.

What does a certification of testing through NVSL mean?
NVSL sends out proficiency tests to participating laboratories. The PCR proficiency test consists of several fecal samples from known-positive and known-negative animals. The laboratories do not know the status, however. In order to be awarded a proficiency certificate, the participating labs have to identify the samples correctly. Correct identification means that the staff in the lab has the knowledge and the resources available to provide accurate testing. There are different certificates — one for the individual animal MAP detection PCR, one for the pooled MAP detection PCR (combination of five samples into one), and one for the antibody ELISA test.

Why is it so difficult to detect the presence of MAP in early infected animals?
During the early phase of infection (subclinical, without any noticeable signs of disease) MAP bacteria are either not shed at all, or are shed only intermittently. There are simply not enough MAP bacteria contained in samples taken during that time for the test to be able to detect.

Are there vaccines available to protect my animals against Johne’s disease?
Yes, there is one, licensed for use in the U.S., but the protective effect is limited. The vaccine can prolong the subclinical phase of the infection so the progression into clinical disease is slowed. It may reduce shedding of MAP and clinical disease but it cannot prevent shedding and infection of youngstock altogether. The vacine can, however be a part of a comprehensive test-and-cull control program. Since vaccinated animals also tend to test positive in the bovine tuberculosis test, the use of the vaccine is only possible under strict control by state veterinary officials. Vaccination may also have potentially significant side effects, including strong granulomatous reaction at the injection site. Vaccinated animals will also react positive in the MAP antibody ELISA test, so the ELISA can no longer be used as a screening test.

Two animals in my herd tested positive. Do I have to, or does my veterinarian have to, report that to the state veterinarian?
No, there is no mandatory reporting of Johne’s disease test results. Producers can voluntarily participate in an eradication program and results obtained under that program have to be reported to the program administrator. Different states will have different programs and program requirements may vary slightly. There will be no quarantine on farms because of the Johne’s disease status.