UK researchers tackle knowledge gap on norovirus
and handling can reduce the spread of noroviruses, one of the most
common causes of gastroenteritis.
Norovirus is highly contagious and can be spread through human contact. But it can also be spread from the environment to food. While the disease results in fewer hospitalizations than some foodborne bacteria such as salmonella, it is much more common and can cause serious illness. It is difficult to assess how much food is contaminated with the virus although estimates suggest between 6-20 per cent of norovirus outbreaks may be attributed to food. In one case, five norovirus outbreaks affecting several hundred people in Denmark in 2005 were traced to a single batch of contaminated frozen raspberries. However viruses tend to be less well-researched than other food pathogens. A major new £800,000 research project, part sponsored by the UK's Department of Environment, Farming and Rural Affairs (DEFRA) with backing from food companies, is aiming to understand how well norovirus survives food processing. "How well the viruses survive food processing is not well-known because you can't grow them in culture outside of its human host," explained Dr Angus Knight, manager of the research project at Leatherhead Food. Currently most of the investigation done on norvoviruses has been carried out on a surrogate virus that is a derivative of a cat pathogen. A mouse norovirus has also been used but it behaves quite differently to the human norovirus in terms of disease. Working with teams at the University of Surrey and the UK's Health Protection Agency, the Leatherhead researchers are hoping to develop new microbiological approaches for measuring the inactivation of the virus without growing it in culture. "We can use very sensitive molecular approaches to study the virus from clinical samples that we have collected," explained Dr Knight. "Looking at different aspects of the structure of the virus we can see how well it stands up to processing conditions." Human norovirus is known to be resistant to acid for example. This could be a problem for organic growers who replace chlorine washing of fruit and vegetables with an acid-based wash. Understanding norovirus is essential for other kinds of food producers, with consumers increasingly eating out of home and more and more handling of food products. The new research project is also expected to reveal new data on the stability of norovirus, determine the effectiveness of current control measures, and result in a rapid test for monitoring the presence of the virus. The research is supported by several firms hoping to gain from the research including Unilever, Evans Vanodine, Atlas Genetics, McDonald's Restaurants, Waitrose, Carnival, the Scottish Shellfish Marketing Group, Vitacress Salads and Premier Foods.