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Fields & Applications Food, Beverage & Agriculture

To Test or Not to Test

New health threats concerning the food industry feature regularly in the media. But differentiating true emerging organisms of concern from the background noise is difficult – and addressing those threats within food businesses even more of a challenge. Those in the industry must recognize the hazards relevant to their products, assess the risks, and then manage them through prerequisite programs (the foundation of good hygiene practices) and the use of food safety hazard analysis and critical control point (HACCP) principles.

Microbiological testing can provide verification that HACCP and Good Manufacturing Practices are working. However, with some emerging organisms of concern, it may be challenging to carry out verification testing, and even more difficult to interpret the results.

Foodborne viruses, including norovirus, hepatitis A and hepatitis E, cannot grow or multiply on foodstuffs, but some products, such as bivalve mollusks, leafy vegetables and berries contaminated with water containing infected human waste, can act as vectors for their transmission to humans (via the fecal–oral route). Resulting illness can vary from self-limiting gastrointestinal symptoms to more serious liver inflammations. And though 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 (1).

Foodborne virus testing in foods is challenging, particularly when it comes to the recovery of low levels of strongly adherent viral particles, which may be protected in microscopic crevices or within the digestive gland of bivalve mollusks. Even the best methods available may only recover one percent of the viral particles present.

Given the information gaps that currently exist, should food businesses already be testing for foodborne viruses to verify the effectiveness of the controls they have in place?

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 people consuming the food are at risk of foodborne illness, of course. The infective dose from foods is not known, though may be as low as ten 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 analysis. Molecular techniques, unlike conventional cultural microbiology methods, are expensive and complex to perform, increasing the cost per test from a few pounds (GBP) to perhaps a few hundred pounds.

Clearly, testing does not assure food safety, and producers/manufacturers already have procedures in place that minimize the risk of contamination of 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 they have in place?  If viral particles are detected on foodstuffs, what remedial action should food businesses take? Is there a risk that product will be removed from sale when it doesn’t 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 continues to better understand these viruses, and methods for their testing are being refined and improved upon. In three to five years, we may even be in a position to include these organisms in routine verification testing of at-risk foodstuffs.

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  1. www.who.int/foodsafety/publications/foodborne_disease/fergreport/en/
About the Author
Catherine Cockcroft

Employed within Eurofins (previously Exova) since 2010 as a technical expert microbiologist in the UK, Catherine is now Head of Microbiological Services, leading the strategy for Eurofins microbiology testing services. She has more than 20 years’ experience as a microbiologist and food safety expert working for large multinational food manufacturers, and is experienced in the microbiology of food and water, microbiology test method development and validation, food safety management systems and technical projects.

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