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How does the virus end up on your plate?
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Foodborne infections can be caused not only by bacteria, but also by viruses. A common cause? Poor hygiene.
Noroviruses – they are particularly feared in nurseries, care homes and even on cruise ships. As few as 10 to 100 of these tiny diarrhoea- causing pathogens are enough to make a person ill. Particularly where many people gather in confined spaces, isolated cases of illness can quickly turn into a full-blown outbreak.
This is because the pathogens are primarily transmitted from person to person. However, contaminated food can also be a source of infection – and spread noroviruses as well as some other viruses.
“Viruses can end up on food if sick people are not sufficiently rigorous about hygiene and spread the pathogens in their surroundings,” explains Reimar Johne, who studies foodborne viruses at the German Federal Institute for Risk Assessment (BfRshort forGerman Federal Institute for Risk Assessment).
“It can also occur if the food comes into contact with contaminated water, for example during the harvest or further processing.” Experts refer to this as faecal-oral transmission; in addition to noroviruses, rotaviruses and hepatitis A viruses can also spread in this way.
During food inspections, viruses are frequently detected on frozen fruit, and shellfish are also often mentioned in connection with viral foodborne infections. “In principle, however, all foods can transmit viruses if they are grown, produced or processed under poor hygienic conditions,” says Johne.
During food inspections, viruses are frequently detected on frozen fruit and in shellfish.
HEPATITIS INFECTIONS ONLY BECOME NOTICEABLE LATER
The situation is somewhat different with hepatitis E viruses. “These viruses are widespread in domestic and wild pigs,” says Eva Trojnar from the National Reference Laboratory (NRL) for Foodborne Viruses. “People therefore usually become infected when eating raw or undercooked pork.”
Unlike diarrhoeacausing pathogens, which trigger symptoms within hours or days, infection with hepatitis E or A viruses initially goes unnoticed. It is only weeks or months later that the infection may manifest as liver inflammation.
RESEARCH OBJECTIVE: MINIMISING HEALTH RISKS
Reliable methods are needed to detect contamination. This is precisely what Trojnar and her team at the NRL are working on. “We are developing new methods or improving existing ones,” says Trojnar. “This includes, for example, adapting the procedures for different types of food. After all, it makes a difference to detection whether the virus is present in a sausage sample or on a leaf of lettuce.”
However, the virus researchers at the BfRshort forGerman Federal Institute for Risk Assessment are also investigating fundamental questions: How widespread are certain viruses in different animal species and foods? How stable are they and how can they be safely inactivated? How can contamination of food be prevented?
The aim is to identify health risks to consumers at an early stage and to develop strategies to minimise them.
