Salmonella in feed
The Swedish Board of Agriculture is the authority responsible for the official statistics on salmonella in feed. Every feed manufacturer is obliged to take a certain number of samples each week, depending on what type of feed they produce (at least five samples for manufacturers of poultry feed and a minimum of two samples for manufacturers of feed for other food-producing animals) in selected places along the production line based on HACCP (Hazard Analysis Critical Control Points). Approximately 8500 to 9500 samples are taken every year. Approximately 0.4 to 0.6 per cent has been positive. It is extremely rare to find positive samples after heat treatment.
Until 2005, the statistics also included follow-up samples sent in to SVA. Follow-up samples are taken when salmonella is found in the weekly samples. In 1991, Sweden introduced a new control program for salmonella in feed based on the HACCP principles. Since then the number of positive salmonella samples has decreased significantly with some exceptions, such as in 2003 when there was a major feed related salmonella outbreak.
In addition to the mandatory weekly sampling, the manufacturers also take own control samples to be able to guarantee that their feed does not contain salmonella.
Salmonella infected herds in food-producing animals
Only a small number of newly infected herds are detected each year. From an international perspective, this is unique and reflects the favourable salmonella situation in Sweden.
In cattle, the number of primary cases has steadily decreased during the 1970´s and 1980´s when more than 100 herds were detected annually. During the late 90´s the situation stabilised, and between 5 and 13 herds per year were detected.
In pigs, the number of primary cases decreased significantly in the late 1970´s, and today approximately five infected herds have been detected each year. Exceptions to this were in the years 2003, 2007 and 2008 when 30, 10, and 8 primary cases were found, respectively. The high number of primary cases in 2003 was caused by an outbreak of Salmonella Cubana, which was traced to contaminated feed.
In broilers, the number of primary cases has decreased significantly since the late 1980`s, but during 2006-2008 and 2010, the number of salmonella positive broilers did increase slightly to between 7 and 11 holdings per year. Part of the increase was caused by an outbreak of S. Typhimurium in a breeding flock in 2006/2007 and problems of repeated re-introductions in a herd where it was difficult to clear the infection. However, it is too early to conclude whether the increase is temporary or more permanent. In the statistics on the number of primary cases in broiler flocks, breeding flocks are also included.
In recent years, salmonella has been detected in 1 to 5 flocks of laying hens annually.
Surveillance in food-producing animals
A continuous and systematic surveillance of salmonella in cattle, adult pigs and pigs for fattening is taking place at slaughterhouses. The purpose is to document the low prevalence of salmonella in slaughtered cattle and pigs and was a prerequisite for Sweden to receive additional guarantees for salmonella from the EU. The National Food Administration is the authority responsible for the official statistics.
The results show that the percentage of animals infected with salmonella is extremely low. Less than 0.2 % cattle, < 0.3 % pigs for fattening and < 0.4 % adult pigs have positive findings of salmonella in the intestinal lymph node.
Food of animal origin
A continuous and systematic surveillance of salmonella in food of animal origin has been taking place at slaughterhouses which slaughter cattle, pigs, and poultry and at cutting plants handling cattle-, pig- and poultry meat. The purpose is to continuously document the prevalence of salmonella in food products or the environment in which they are handled (cutting plants), and was a prerequisite for Sweden to receive additional guarantees for salmonella from the EU. The National Food Agency (livsmedelsverket.se) is the authority responsible for the official statistics.
The results of the surveillance of food in slaughterhouses and cutting plants show that domestically produced food of animal origin is virtually free from salmonella. Less than 0.1 % of carcasses of cattle, adult pigs and pigs for fattening, <0.2 % of neck skin samples from poultry and ≤0.1 % of the samples from cutting plants that handle cattle, pig and poultry products were positive for salmonella.
Salmonella infection in humans
In the end of the 1980's and early 1990's approximately 5000 people (incidence 56/100,000) were reported with salmonella infection. The number of reported cases declined in the mid 2000´s to 3500 but has in recent years increased slightly. In 2013, 2838 cases were reported. The majority (approximately 80-85%) of the reported cases were infected abroad. The low number of cases infected domestically, out of the total number of reported cases, reflects the favourable salmonella situation of the Swedish food-producing animals. In recent years, it has become more common for different types of vegetables to be associated with salmonella outbreaks. These types of products often come from countries other than Sweden, and are often eaten without being heat-treated first.
It should be noted that a comparison cannot be made between reported salmonella cases in humans in different countries since the reporting systems differ greatly between countries.