Cost-efficient sampling is an important part of a control program. However, all tests are imperfect. The accuracy, efficiency and added value of testing depends on many factors such as the purpose of testing, the tests used, the sampled material, type of samples taken, number of samples taken, and occurrence within the sampled population or material. Investigation of the accuracy and efficiency of different tests and sampling strategies is an area of SVA research.
Salmonella in feed
One of SVA research areas in connection to salmonella in feed is sampling strategies. Due to low levels and non-uniform distribution of the bacteria in the feed materials representative sampling is made difficult. SVA is supporting the feed producing companies in their aim to produce a salmonella-free feed by applied research and consulting. In the feed mills there is a surveillance to ensure the absence of Salmonella in the production lines as well as in the feed mill environment. A safety management system is applied in the processing line according to the HACCP (Hazard Analysis and Critical Control Points) principles.
Salmonella in the environment
The environment offers a possible route for transmission of salmonella from infected individuals into the feed and food-chain and to animals and humans. The bacteria are known to be able to survive extended periods in the environment and even multiply under favourable conditions. Therefore, efforts are put in to minimizing the spread of salmonella into the environment and from the environment. SVA focus on investigation of factors affecting survival and regrowth in the environment and treatment techniques and barriers to minimize spread of salmonella into the environment.
Salmonella in cattle
Most herds detected with salmonella are cattle herds. Open housing systems and grazing means that cattle are exposed to the environment more than most pig herds and poultry flocks. Sewage from water treatment plants and slurry from other herds may contaminate the environment and cause infection in exposed animals and herds. Structural changes in the cattle production sector have led to larger herds with following differences in types of housing and management factors which may affect the persistence of salmonella in herds. These factors present challenges in control of salmonella in cattle herds and are a focus in salmonella research at SVA.
Estelle Ågren, epidemiologist