Testing for emerging organisms of concern

Catherine Cockcroft of Eurofins discusses the right time to start testing for emerging organisms of concern.

The media continually makes us aware of new threats that  the food industry seemingly needs to worry about. Differentiating the true emerging organisms of concern from the background noise is difficult and addressing those threats within food businesses is even more of a challenge. Responsible parties must recognise the hazards relevant to their products, assess the risks and manage them through the use of HACCP principles and pre-requisite programmes. Microbiological testing can provide verification that HACCP and GMP are under control. However, verification testing for some of the emerging organisms of concern may not be straightforward to carry out and it may be even more difficult to interpret the results.

Foodborne viruses, including Norovirus, Hepatitis A and Hepatitis E, cannot grow or multiply on foodstuffs, but products, such as bivalve molluscs, leafy vegetables and berries, contaminated with water containing infected human waste can act as vectors for their transmission to humans via the faecaloral route. Resulting illness can vary from self-limiting gastrointestinal symptoms to more serious liver inflammations. While the true burden of illness attributable to contaminated food is not known, it is estimated that Norovirus is the most common cause of foodborne illness in the European region with close to 15 million cases each year, causing more than 400 deaths (source: WHO estimates of the global burden of foodborne diseases: foodborne disease burden epidemiology reference group 2007-2015).

Testing foodborne viruses in foods is challenging, particularly the recovery of low levels of strongly adherent viral particles, which may be protected in microscopic crevices or within the digestive gland of bivalve molluscs. The best methods available may only recover 1% of the viral particles present in the food. Complex molecular techniques detect the presence of viral particles and results are expressed in numbers of viral genome copies. Detection in itself does not necessarily mean that the people consuming the food are at risk of foodborne illness. The infective dose from foods is not known, though may be as low as 10 viral particles. Furthermore, the presence of viral RNA does not necessarily mean that the particle is capable of infectivity. Another consideration is the cost of performing the testing. Molecular techniques, unlike conventional cultural microbiology methods, are expensive and complex to perform, increasing the cost per test from a few pounds to perhaps a few hundred pounds.

Clearly, testing does not assure food safety, and producers/manufacturers already have procedures in place that minimise the risk of contamination of the foods by foodborne viruses. Given the information gaps that currently exist, should food businesses already be testing for foodborne viruses to verify the effectiveness of the controls = that they have in place? If viral particles are detected on foodstuffs, what remedial action should the food business take? Is there a risk that product will be removed from sale when it does not present a true risk to the consumer. Or is the risk greater to the consumer if food businesses choose not to perform any verification testing. At this early stage in the understanding of these micro-organisms, caution is advised before rushing into full scale routine testing. Producers and manufacturers should anticipate how they will react to detection of these organisms and be ready to enact those processes should the need arise. In the meantime, research to better understand these organisms, and to plug the knowledge gaps continues. Methods for their testing are being refined and improved. In 3-5 years, we may be in a position to include these organisms in routine verification testing of at risk foodstuffs.

Eurofins offers ISO 17025 accredited Norovirus and Hepatitis A Virus testing of foodstuffs from our network of European laboratories. For more information contact our UK laboratory on 0845 604 6740 or email

Catherine Cockcroft

Head of Microbiological Services

Eurofins Food Testing UK Limited

0845 604 6740

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