Salmonella surveillance

All types of pig populations in Danish pig production are monitored for salmonella. The surveillance ensures that the occurrence of salmonella will remain at a low level in Danish pork. The surveillance of salmonella is risk-based in order to guarantee that pig populations with previous outbreaks of salmonella are monitored very carefully.

The occurrence of salmonella is monitored at all levels of primary production in Danish pig production. In breeding and propagation populations, ten blood samples are taken each month. Based on these results, an index is calculated and if index 5 is exceeded, stool samples must be taken in order to ascertain which type of salmonella has caused the reaction.

Breeding and propagation populations are divided into A, B and C based on the samples.

• A are populations without any signs of salmonella
• B are populations with findings of less important types. These are types that rarely cause long-term problems in the population and that rarely cause infections in humans.
• Populations with findings of salmonella typhimurium, infantis and derby are assigned C status.

Sow populations are divided according to the same criteria. The surveillance is risk-based. If a sow population with A status supplies pigs to a slaughter population that is later given level 2 and 3, stool samples must be taken in order to examine if the infection has come from the sow population.

Abattoirs also monitor the occurrence of salmonella in the pigsties
Slaughter pig populations are monitored by means of meat juice samples taken by the abattoir. The meat juice sample is examined for antibodies against salmonella and based on the meat juice samples, a slaughter index is calculated. Populations with an index above 65, are assigned level 3. Pigs from these populations must be slaughtered separately with increased hygienic monitoring or slaughtered with subsequently washing with hot water (VVS).
Populations with an index between 40 and 65, are assigned level 2.
Slaughter pigs at levels 2 or 3 are paid at a lower price.

Between 1 and 1.5 per cent of the pig population is at level 3, and 2 to 3 per cent of the pig population is at level 2.

Relevant links:
SEGES, the Knowledge Centre for Pig Production  
The Danish Veterinary and Food Administration