New and improved diagnostic tests make more pathogens visible at lower costs. Abattoirs have a great need for this. This will allow them to easily demonstrate that pork, chicken and milk are free from a variety of contagious and other diseases. Wageningen UR is developing new diagnostic technologies for this purpose.
During the course of their lifetime, pigs, chickens and cows come in contact with all sorts of pathogens. Some of these are completely harmless for the animals themselves, but can make people ill. These types of pathogens are called zoonoses. One example is the Salmonella bacterium that occurs in pigs and chickens. Another example is Trichinella, a worm that can cause very serious symptoms in humans. All other pathogens only cause symptoms in the animals themselves. Some diseases have been completely banned from import within an EU context, as is the case with Aujeszky’s disease. Unlike older pigs, there is a high risk of fatality among young piglets which have become infected with Aujeszky’s disease. Sows that are infected abort their piglets.
New diagnostic tests
In the Netherlands, both live and slaughtered animals are tested for certain pathogens or the antibodies to these pathogens. This system contributes to healthy animals and safe food. Occasionally, regulations change and new or improved tests are necessary. For the development of new tests, the Central Veterinary Institute applies the most modern diagnostic technologies which are less expensive, faster or easier to use.
Monitoring system
For many diseases, it is enough to merely conduct random testing. In a monitoring system like this, it is not the individual animal results that matter, but the information on a population. To achieve this, other tests are required than those which are used for testing individual animals. Years of data from random testing show the degree to which a certain pathogen has been circulating at a company. Armed with this data, an abattoir or a farmer can take targeted measures themselves to reduce the incidence of the pathogen.
The CVI is currently working on tests that are specially designed to monitor diseases such as paratuberculosis (Johne's disease), avian tuberculosis and Aujeszky’s disease.
Surface plasmon resonance
New tests are based on Surface plasmon resonance (SPR). This is a technology whereby the presence of pathogens is demonstrated on the basis of mass change. The benefit of this test is that it is easy to perform and that it requires very few steps.
The CVI has now developed SPR tests for Salmonella and Trichinella. The test for Trichinella has only been allowed since 2006, provided certain boundary conditions are satisfied. Before that time, the EU required testing every animal for the presence of the worm. The meat would only be allowed to be processed for consumption if the results were negative. Since this worm does not occur in the Netherlands in intensive pig farming, abattoirs would like to convert to random testing. This would allow them to combine this with SPR testing for Salmonella and Aujeszky’s in pigs so that they can perform all of the testing at the same time.
Serological test
A serological test can be used to determine the presence of antibodies to pathogens in the animal. Developing a serological test is a complicated process since these tests never provide absolute certainty of whether or not an animal is infected. Pigs that had never come in contact with a pathogen have nonetheless tested positive in certain cases. Other aspecific antibodies are the cause of this. The opposite has also been known to happen. A test in which animals are infected with the pathogen in a controlled environment provides more certainty. This is therefore the first step in developing a test. In addition, it is important to find out how and by what means the presence of antibodies may best be demonstrated.
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