Data on trends and sources of zoonoses, and zoonotic agents and food-borne outbreaks in the European Union indicate that poultry and poultry products present a high potential risk of transmission of zoonotic agents to humans. To reduce the prevalence of certain zoonoses in animal populations and at other appropriate stages of the food chain, the European Union established rules and targets.
By Lüppo Ellerbroek, Veronica Cibin and Antonia Ricci
According to the report on trends and sources of zoonoses, and zoonotic agents and food-borne outbreaks in the European Union by the European Food Safety Authority (EFSA) in 2008 approximately 80% of human Salmonellosis cases are caused by Salmonella Enteritidis and Salmonella Typhimurium which is similar to preceding years. Poultry meat and products thereof were once again the most frequently reported cause of food-borne outbreaks in the EU, with eggs and products made with raw eggs being the most important food vehicles in these outbreaks. From all serovars S. Enteritidis was the most frequently isolated in table eggs and also frequently found from poultry meat. In compound feeding stuff, the proportion of Salmonella-positive findings ranged up to 8.3% in poultry feed.
Reducing human cases
The primary objective of food-borne zoonotic pathogen control is to reduce the incidence of human disease. Ideally, this is achieved by elimination of the pathogen at the most appropriate stage(s) in the food chain, including feed production, primary production, food processing, storage, transport and retail sale; the improvement in consumer information and an agreement on food safety controls criteria within EU Member States.
Following the integrated approach throughout the food chain from farm to table the European Parliament and Council have agreed on two legal acts on zoonoses:
- Directive 2003/99/EC on the monitoring of zoonoses and zoonotic agents,
- Regulation (EC) No. 2160/2003 on the control of Salmonella and other specified food-borne zoonotic agents.
Zoonoses Directive 2003/99/EC includes three elements of legislation dealing with:
- monitoring of zoonoses and zoonotic agents and antibiotic resistance in farm animals and food, but also wildlife and feed, including coordinated baseline studies,
- investigating food-borne disease outbreaks; and
- submitting annual reports on national ‘trends and sources’ to the EU Commission and to the EFSA.
Further on the directive asks the Member States of the EU for foodborne disease outbreak investigations. These investigations include the epidemiological profile, the foodstuffs potentially implicated and the potential causes of the outbreak. Regulation (EC) No. 2160/2003 is particularly focused on the control of zoonotic salmonellae throughout the application of sanitary measures at primary production level as a consequence of the identification of relevant salmonellae serovars.
The key points of this regulation are:
- the definition and identification of relevant serovars,
- the identification of harmonised targets within, and
- the application of control plans, approved by the EU, based both on sampling by food business operator and official controls by Competent Authority.
Targets to be achieved
According to the deadlines starting from 2005 specific regulations have been issued defining the target for the prevalence reduction in each animal category including specifications regarding:
- serovars to be considered as relevant for public health,
- frequency and status of sampling,
- sampling protocol,
- examination of the samples including transport and preparation of the samples,
- detection method,
- serotyping, and
- calculation of prevalence for the verification of the community target and reporting.
Regulation (EC) No. 2160/2003 provides in Annex II the general criteria for control programs as well as criteria for food and feed producers entering these programs. Further to these targets also control measures are planned for poultry (breeding flocks of Gallus gallus, laying hens, broilers, turkeys) coming into force in December 2011 by amending both the Regulation (EC) No. 2160/2003 and (EC) No. 2073/2005. The European Union expects that setting a criterion for Salmonella Enteritidis and Salmonella Typhimurium would provide the best balance between reducing human Salmonellosis attributed to the consumption of poultry meat and the economic consequences of the application of that criterion.
It should be noted that this requirement for Salmonella in poultry meat was already included as one element of a broader legislation before (particularly Regulation (EC) No. 2073/2005) laying down microbiological criteria in general. The Regulation (EC) No. 2073/2005 [which deals with both processing and end product microbiological criteria for food stuffs (including Salmonella)] stipulates that the criteria for meat and products thereof should take into account the expected improvement in the Salmonella situation at the level of primary production.
The criteria for the public health importance of the Salmonella serotypes are defined in the Regulation (EC) No. 2160/2003:
- the most frequent Salmonella serotypes (top 5 or top 10) in human Salmonellosis on the basis of data collected through the EU monitoring system,
- the route of infection,
- whether any serotype shows a rapid and recent ability to spread and to cause disease in humans and animals, and
- whether any serotype shows increased virulence, for instance as regards invasiveness, or resistance to relevant therapies for human infections. Initially for a three year transition period the five most important Salmonella serotypes (S. Enteritidis, S. Hadar, S. Infantis, S. Typhimurium, S. Virchow), as revealed by the human reporting system, will be targeted while an extension to other serotypes will be based on an assessment of the benefits and costs of controlling that Salmonella type.
Specific Control Options:
- restocking only with vaccinated animals in case of breeders and laying hens,
- killing or slaughtering of flocks positive to relevant serovars in case of breeders and laying hens,
- increase in control frequency according to epidemiological investigation results, and
- destruction of hatching eggs produced by groups positive to relevant serovar.
Critical aspects for implementation
The experience in applying control plans at national level gives rise to some considerations. Therefore some critical aspects should be taken into account before starting a salmonella control campaign:
- the nature of the collaboration or agreement between the competent authority and food business operator,
- structure of the production system,
- sanitary measures already applied,
- sanitary measures not applicable or difficult to be applied according to the existing situation,
- Salmonella prevalence (including serovar distribution and identification of relevant serovar) according to the animal category,
- number and location of competent laboratories for testing official samples and samples taken by FBO and available analytical methods, and
- availability of a reporting system.
Target come into force
In the EU targets for poultry breeding flocks (laying hens, broilers and turkeys) comprised not only a numerical expression of the proportion of the animal population remaining positive for Salmonella but also the maximum time limit for achieving the target and the definition of the testing schemes necessary to verify achievement of the target. These targets come into force in December 2011. The European Union expects that setting criterion for Salmonella Enteritidis and Salmonella Typhimurium would provide the best balance between reducing human salmonellosis attributed to the consumption of poultry meat and the economic consequences of the application of that criterion.
*Lüppo Ellerbroek works at the Federal Institute for Risk Assessment (BfR), Germany and Veronica Cibi and Antonia Ricci work at the OIE Reference laboratory for Salmonella, Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro (PD), Italy.