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Food-borne diseases

Food-borne diseases
Food-borne diseases are caused by pathogenic microbes such as bacteria, viruses, and parasites, or their toxins present in contaminated foods  Many microbes of this sort are commonly found in the intestines of healthy food producing animals. The risks of contamination are present from farm to fork and need to be controlled in different ways.

Food can become contaminated at different stages in the food chain. During slaughter meat can be contaminated by coming into contact with small amounts of intestinal contents.  At the food processing stage microbes can be introduced by cross-contamination from another raw agricultural product or from infected humans handling the food.  In the kitchen microbes can be transferred from one food to another by a kitchen utensil used to prepare both without washing in between. Proper cooking of the foodstuffs kills the pathogenic microbes.

Some food-borne diseases are classified as food-borne zoonoses – diseases or infections that can be transmitted from animals to humans through food. Zoonoses also include diseases transferred to humans by other routes than food, for example by direct contact with animals. They are reported to affect over 380,000 EU citizens each year.

Common food-borne diseases

The most common food-borne infections in the European Union (EU) are caused by the bacteria such as Campylobacter, Salmonella, Listeria and viruses. They enter the body through the gastrointestinal tract and the first symptoms often occur there. Many reported food-borne illnesses are not part of recognized outbreaks but are registered as individual cases. 

Bacteria that cause food-borne diseases include among others Salmonella, Campylobacter, Listeria, pathogenic Escherichia coli, Yersinia, Shigella, Enterobacter and Citrobacter. In addition, food-borne diseases can be caused by bacterial toxins. Bacterial toxins are toxins generated by bacteria and may be highly poisonous in many cases. These include toxins from Staphylococcus aureus, Clostridium botulinum and Bacillus cereus.

The most commonly identified bacterial cause of diarrhoeal illness in the EU is Campylobacter. Raw poultry meat is often contaminated with Campylobacter since these bacteria can live in the intestines of healthy birds. Eating undercooked chicken, or ready-to-eat food in contact with raw chicken, is the most common food-borne source of this infection. It causes fever, diarrhoea and abdominal cramps.

Salmonella is a bacterium also commonly found in the intestines of birds and mammals.  It can spread to humans via foods especially through meat and eggs.  The illness it causes, salmonellosis, usually involves fever, diarrhoea and abdominal cramps. If it invades the bloodstream it can cause life-threatening infections. 

Listeria
cases in humans, although less common than Campylobacter and Salmonella, have a high mortality rate particularly among vulnerable groups such as the elderly. It is also very dangerous to pregnant women as it can cause foetal infections, miscarriages and stillbirths. Ready-to-eat foodstuffs, such as cheeses and fish or meat products, are often found to be at the origin of human infections.

Food-borne diseases can also be caused by viruses, such as calicivirus (including norovirus), rotavirus and hepatitis A virus. These are primarily transmitted by food or water contaminated with human waste. Calicivirus causes approximately 90% of epidemic non-bacterial outbreaks of gastroenteritis in the world.

Parasites can also be present in food or in water. Parasites that may be transmitted through consumption of contaminated food or drinking water include Trichinella, Giardia, Sarcocystis and Cryptosporidium.

EU framework

The food hygiene package of EU legislation sets out hygiene requirements for food producers and operators and provides rules for official controls of fresh meat, milk and other foods. This is an important regulatory basis for minimising the prevalence of food-borne diseases as part of a farm to fork approach to food safety.

The framework for monitoring and controlling food-borne diseases is contained in EU legislation on zoonoses. Directive 2003/99/EC on the monitoring of zoonoses and zoonotic agents sets up a system of collecting and analysing data from the Member States on the prevalence of pathogenic bacteria in different animal populations. The EU develops control measures to prevent and reduce these bacteria based on this monitoring data.

Regulation (EC) 2160/2003 sets out EU measures to control Salmonella and other specified food-borne zoonotic agents. To implement it, the European Commission has adopted specific Regulations for instance on the use of antimicrobials and vaccines for poultry, intra-Community trade restrictions on table eggs, and restrictions on imports of live poultry from third countries. The Commission has also set targets that Member States need to meet to reduce Salmonella in different animal populations, including laying hens, broilers, turkeys, fattening pigs and breeding pigs. 
 
 
Commission Regulation (EC) No 2073/2005 on microbiological criteria for foodstuffs lays down food safety criteria for certain important food-borne bacteria, their toxins and metabolites, including Salmonella and Listeria, in specific foodstuffs. Ultimately the safety of foodstuffs needs to be ensured by a preventative approach covering product and process design and applying internationally recognised industry standards such as Good Hygiene and Manufacturing Practices (GHP and GMP) and Hazard Analysis Critical Control Point (HACCP) principles. 

 EFSA’s role and activities

EFSA provides scientific support and advice to risk managers through collecting and analysing data on zoonotic bacteria in animal populations and in food and feed, assessing the risks for the food chain and making recommendations on their prevention and reduction.

The Panel on Biological Hazards (BIOHAZ) provides independent scientific advice on biological hazards in relation to food safety and food-borne diseases. It carries out risk assessments to produce scientific opinions and advice for risk managers. The Panel’s risk assessment work provides a sound foundation for European legislation and supports risk managers in taking effective and timely decisions. Examples of the Panels work include:

  • An assessment of the risks of microbial contamination of animal feed published in July 2008. Feed can be contaminated with bacteria such as Salmonella, and this can cause infections in animals which can potentially lead to human infection from derived food products. The opinion focused on industrially produced feed which is most prone to Salmonella contamination.
     
  • An opinion on the risks of Listeria monocytogenes related to ready-to-eat foods published in January 2008. The Panel recommended measures to ensure that ready-to-eat foods are of low risk for humans, including the application of microbiological criteria alongside GHP and HACCP principles.
     
  •  An opinion on risk assessment and mitigation options of Salmonella in pig production published in April 2006. The Panel made a set of recommendations to reduce Salmonella in live pigs through management measures at each stage of the food chain including transport-lairage, slaughter, processing and retail. 
     
  •  An opinion on Campylobacter in animals and foodstuffs published in April 2005. This assessed the food-borne routes of campylobacteriosis and identified possible control options as well as data gaps to be addressed. Among its conclusions it identified poultry meat as a major source of campylobacteriosis and showed that risks to consumers can be considerably lowered by reducing contamination in poultry flocks and poultry carcasses. 
     
  •  Opinions on the use of vaccines and the use of antimicrobials for controlling Salmonella in poultry, published in December 2004. These looked at the risks and benefits of the two control options. The Panel concluded that using antimicrobials to control Salmonella in poultry has little justification from a food safety and public health perspective. It argued that vaccination may be useful in reducing excretion and egg contamination for the most common Salmonella serovars in Europe, but recommended good farming and hygienic practices plus the testing and removal of positive flocks from production as the best basis for controlling Salmonella in poultry farms.

Under the zoonoses legislation, EFSA’s Unit on Zoonoses Data Collection supported by a Task Force comprised of Member State experts monitors data on zoonotic bacteria and parasites across the EU.

  • The unit produces the Annual Community Summary reports on infectious diseases transmissible from animals to humans, in cooperation with the European Centre for Disease Prevention and Control (ECDC). These reports illustrate the evolving situation in the EU and identify the pathogens that cause the most common human infections. In its Community Summary report on zoonoses and zoonotic agents for 2007 EFSA found that Campylobacter was, as in the previous year, the most reported animal infection transmitted to humans and that the number of Salmonella infections decreased for the fourth year in a row. The second part of the report on food-borne outbreaks showed that Salmonella and food-borne viruses continued to be the main causes of reported food-borne outbreaks in the EU. 
     
  • EFSA reviews the Annual Community Summary reports and makes recommendations on prevention and reduction measures. In September 2006 EFSA’s BIOHAZ and AHAW Panels worked with the ECDC to provide recommendations on preventing and reducing animal diseases transmissible to humans including salmonellosis, campylobacteriosis, listeriosis and toxoplasmosis. The opinion also identified antimicrobial resistance among pathogenic bacteria as a public health concern and made recommendations including mandatory monitoring of the use of antimicrobial treatments in food producing animals.
     
  •  The Zoonoses Unit also analyses and produces baseline survey reports on the prevalence of Salmonella and other food-borne zoonotic agents in food and in various animal populations including chickens, turkeys and pigs. These provide a scientific basis for EU prevention and reduction measures including target-setting.
     
  •  The Task Force also produces guidance for national authorities on monitoring and reporting activities, including on antimicrobial resistance in pathogenic bacteria.

 For more information

Scientific Documents  
Joint Opinion on antimicrobial resistance (AMR) focused on zoonotic infections

Published: 16 November 2009  Adopted: 28 October 2009