24 November 2009

5 minute read

The European Community has a system for monitoring zoonoses, which obliges the European Union Member States to collect relevant, and where applicable, comparable data on verotoxigenic Escherichia coli (VTEC) in animals and foodstuffs.

This all falls under the Directive 2003/99/EC (EC, 2003).

However, the food authority says that currently there are no harmonised rules or recommendations for the monitoring of VTEC in animal populations and food categories in the EU, even though most MSs carry out monitoring.

The stage of sampling, the types of samples taken, and the analytical methods used vary from country to country and also between investigations.

This lack of harmonisation has hampered the analyses of data at Community level and therefore there is no clear picture of the occurrence of human pathogenic VTEC serogroups in the relevant animal populations and food categories in the Community.

The objectives of these technical specifications are to recommend a harmonised methodology to be used in the monitoring of the most relevant animals and foodstuffs throughout the EU.

Based on the opinion of the scientific panel on Biological Hazards on the monitoring of VTEC and the identification of human pathogenic VTEC types (EFSA, 2007), harmonised technical specifications are proposed for the monitoring and reporting of VTEC in relevant animal populations and foodstuff categories.

EFSA believes that these technical specifications, once implemented, would ease a better analysis of the situation at Member State and Community levels.

The prevalence of VTEC 0157 is assessed at slaughter through risk based sampling. This is done by estimating the amount of contamination on the hides of young cattle and on sheep fleeces at slaughter.

Cattle are the main reservoir of VTEC O157 and will constitute the study population.

EFSA says that VTEC O157 is the serogroup most often reported in human VTEC infections, including severe HUS cases and young cattle are assumed to be the most important VTEC reservoir.

Sampling will focus on animals between three and 24 months of age as adolescent cattle have the highest prevalence of VTEC O157, whereas cattle outside this age range are less likely to excrete the pathogen. White veal calves are not targeted by the survey because VTEC prevalence in this population is reported to be low.

VTEC prevalence on hides/fleeces has also been reported to be higher than in faecal samples.

It is recommended that monitoring take place at the slaughterhouse mainly for practical reasons related to the feasibility of sampling, but also because slaughterhouses are often a more consistent environment with less variation than individual farms.

Samples should be distributed according to slaughterhouse throughputs in the country, to represent the number of high risk animals slaughtered at each slaughterhouse. This will eliminate the risk of under/over-representation in large/small slaughterhouses.

EFSA believes that the risk-based approach will enable a cost-effective monitoring and it is recommending to all EU countries that they carry out monitoring at minimum three-year intervals.

EFSA said that the countries can extend the monitoring to include the serogroups of VTEC O26, O103, O111 and O145, which have been identified in some countries as causes of human infections.

EFSA's general guidelines of the monitoring of the prevalence of VTEC 0157 on foodstuffs are proposed for carrying out specific surveys on the food categories that are most likely to be sources of VTEC O157 and non-O157 infections in humans.

The safety authority says that the standardised ISO 16654:2001 (ISO, 2001) method is recommended for the detection of E. coli O157 in food.

This method has been derived from the same ISO that is specifically proposed for the testing of hide and fleece samples.

All isolated E. coli O157 strains have to be confirmed as VTEC by testing for the presence of VT-encoding genes (vtx) and eae by means of a suitable Polymerase chain reaction, such as the one annexed to the document.

EFSA currently uses the draft CEN TC275/WG6 standard, currently submitted to ISO for evaluation, for the detection of serogroups O26, O103, O111 and O145 and it proposes that the current method should be continued. It is based on a Real-time PCR-based horizontal method for screening followed by a confirmation step aiming at the isolation of the VTEC strains.

EFSA says that buffered peptone water without antibiotics is proposed as a single enrichment medium for hide/fleece samples so that the same enrichment culture is used for the isolation of both O157 and non-O157 VTEC and to simplify laboratory protocol. It is hoped by this proposal to harmonise testing across the EU.

Technical specifications for the reporting of harmonised information on the VTEC monitoring programme in animals and foodstuffs as well as on survey results by EU countries in their annual zoonoses reports have also been defined in the EFSA report.

Finally, it is proposed that the technical specifications be reviewed after all the EU countries have carried out surveys of the prevalence of VTEC )157 and the specifications should be looked at again in the light of the results of these first surveys.

The food categories included in the survey as well as samples from hides and fleeces include:

• Carcases
  • Samples from ruminants - bovines, sheep, goats and game ruminants
  • Samples should be taken after dressing but before chilling
  • Samples should be taken in accordance with European Commission Regulation (EC) No 2073/2005 (EC, 2005) (swabbing or excision - technique for carcass sampling)
• Fresh meat from ruminants
  • Meat from bovines, sheep, goat or deer
  • Cuts of meat (large/small) with special focus on meat intended to be eaten raw or with minimal cooking
• Minced meat and meat preparations
  • Meat from bovines, sheep or mixed meat including bovine or sheep meat
  • Special focus on minced meat and meat preparations intended to be eaten raw or with minimal cooking and meat tenderised with "needle techniques"
• Ready-to-eat dried or fermented meat products
  • Fermented sausages, such as salami, pepperoni, containing ruminant meat
  • Products made from bovine, sheep or mixed meats including bovine or sheep meat
• Fresh vegetables and salads
  • Ready-to-eat pre-cut vegetables (leaf salads, spinach etc.)
  • Ready-to-eat sprouted seeds
• Raw and low heat-treated milk and dairy products thereof
  • Raw and low heat-treated milk from cows, goats, and sheep intended for direct human consumption
  • Cheeses, especially soft or semi-soft, made from raw and low heat-treated milk

Further Reading

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You can view the full report by clicking here.