Food Safety Criteria for listeria in smoked and gravad fish, and raw milk cheese are not always met
Listeriosis is rare in humans. However, since they can cause severe illness such as meningitis and miscarriage, foods contaminated with high quantities of listeria - typically smoked or gravad fish, soft and semi-soft cheese made from raw milk - are especially problematic. In contrast, food contaminated with salmonella, are on the decrease. Consistent control programmes in animal populations have contributed to this success. This improvement is also reflected in a decrease in the number of salmonella infections in humans, as the data of Robert Koch-Institute show. For campylobacter too, a decreasing proportion of positive samples in animal populations is observed. Nevertheless, campylobacteriosis continued to be the most common food-borne infectious disease in humans in 2011. Bacteria, found in animal populations and on food, that are multi-resistant to antibiotics continue to pose a problem. They contribute to a situation where consumers are colonised by multi-resistant germs. "Although this decrease in salmonella contamination is quite favourable, it is no reason to give the all-clear. For consumers, raw meet continues to be a source of microbiological hazards and necessitates careful handling of such foods", emphasises BfR President Professor Dr. Dr. Andreas Hensel. Strict compliance with the rules of kitchen hygiene and thorough cooking provide effective protection against food-borne infections. "Food business operators must take suitable measures to ensure that only foods are placed on the market for which the food safety criteria for listeria are not exceeded if they are handled and stored correctly", Hensel clarifies.
As part of an EU-wide baseline study, the BfR has investigated the presence of Listeria monocytogenes in smoked and gravad fish, soft and semi-soft cheese and also in heat-treated meat products. These foods are known to be potential carriers of elevated quantities of listeria. Overall, study results show that the prescribed microbiological criteria for Listeria monocytogenes are not always strictly adhered to in ready-to-eat foods. When limits are exceeded there is a risk of consumers contracting a Listeria monocytogenes infection. It is therefore imperative for food producers to ensure that the regulations are consistently met.
While infections from listeria are much rarer in humans than infections from salmonella and campylobacter, they do pose a special problem due to the severity of the illness they cause. In humans, Listeria monocytogenes can cause severe meningitis and miscarriage. For pregnant women in particular, the recommendation therefore is to refrain from eating smoked and gravad fish and raw milk cheese in order to minimise the risk of infection.
The control programmes against salmonella in poultry populations which have been implemented consistently for years have proved successful for laying hens in particular. Improvements in slaughtering hygiene have also led to a reduction in the salmonella prevalence in beef and pork. The proportion of fresh beef and pork samples contaminated with salmonella was reduced to below 1 per cent in 2011. Slightly higher detection rates were found in minced meat as well as wild boar and poultry meat. The frequency of detection of campylobacter in broilers and broiler meat fell somewhat compared to previous years: in 2011, 25.1 % of animals slaughtered and 31.6 % of the broiler meat samples were contaminated with campylobacter. These are the results of the zoonosis monitoring programme 2011. A comparison with detection rates from previous years clearly shows that in 2011 less salmonella and campylobacter was detected on food. However, for other zoonotic pathogens such as VTEC and Yersinia enterocolitica no decrease was observed. Studies in the years to come will show whether the positive trend for campylobacter is a permanent improvement or not.
The ongoing presence of multi-resistant bacteria both in animal populations and on foods continues to be a problem. It is true that many of these bacteria do not cause direct illness in men or animals. However, the germs can pass on their resistance properties to pathogens, meaning that they can contribute to colonisation of humans with resistant germs. As part of resistance monitoring, 4,717 isolates from the zoonosis monitoring programme 2011 were tested for their resistance to antimicrobial substances. The results confirm the observations of the previous years: especially for fattening poultry, multi-resistant germs are found very frequently, and they are transferred to the meat of these animals as well. 91.8 % and 91.3 % respectively of the E. coli isolates of broilers and fattening turkeys showed resistance to at least one active substance group, whereas 82.9 % and 85.3 % respectively of the isolates were found to be resistant to more than one group. The BfR will publish a detailed report on the current resistance situation of germs on foods to antibiotics in Germany before the end of this year. The data contained therein are collected annually within the resistance monitoring programme and are currently being analysed by the BfR.
Not only foods derived from animals can be carriers of germs. Plant-based foods such as fruit and vegetables too can be contaminated with salmonella, listeria or other pathogenic germs. If handled improperly, they can lead to disease in humans. Contaminated sprouts are seen as the cause of the great EHEC outbreak of 2011. This outbreak showed that lack of knowledge with regard to new and unusual safety hazards still poses one of the main food safety challenges.
Zoonoses are infectious diseases which can be transmitted from animals to humans. The report on zoonosis monitoring is published annually by the Federal Office for Consumer Protection and Food Safety (BVL) and contains representative data on the presence of zoonotic pathogens as well as their antimicrobial resistance in food and animal populations. The data for drawing up the report are collected by the competent authorities of the federal states in accordance with a study protocol set by the BfR. The BfR assesses this data from the viewpoint of consumer health protection.
BfR publish annually a report on the overall situation as regards zoonoses and zoonotic agents in Germany. This report, apart from the results of the zoonosis monitoring programme, also contains the comprehensive results of official food and feed control as well as diagnostic investigations of animals.
The BfR reports can be accessed on the Internet at:
- „Erreger von Zoonosen in Deutschland 2011“ (in german)
- Baseline study on the prevalence of Listeria monocytogenes in specific ready-to-eat foods
- Berichte zur Lebensmittelsicherheit 2011: Zoonosen-Monitoring 2011 (in german)
- The database SurvStat (RKI)
About the BfR
The Federal Institute for Risk Assessment (BfR) is a scientific institution within the portfolio of the Federal Ministry of Food, Agriculture and Consumer Protection (BMELV). It advises the Federal Government and Federal States on questions of food, chemical and product safety. The BfR conducts its own research on topics that are closely linked to its assessment tasks.