Although noroviruses are the largest cause of gastrointestinal disease in the industrialised world, surprisingly little is known about how best to detect or control them, LFR principal consultant Dr Angus Knight told FoodManufacture.co.uk.
“Human noroviruses cannot be grown in culture and this makes the determination of the efficacy of control measures very difficult. Meanwhile, the extent of foodborne contamination is not well understood because it is masked by high person-to-person transmission.”
He added: “Current studies are based on related viruses [such as feline calicivirus and murine norovirus] that can be grown in culture but these may be irrelevant to the way that norovirus behaves.
“This then leads to the second problem that if you can’t grow it in cultures, it’s harder to test the most effective methods for controlling it.”
Established control techniques ineffective
A three-year LINK project backed by the Department for Environment, Food and Rural Affairs (DEFRA) has just concluded that many established techniques for tackling the virus – alcohol-based handwashes and chlorine-based bleaches - were not as effective as previously believed, he added.
LFR, which plans to hold a one-day workshop on tackling norovirus in early January, has developed some new molecular methods of detecting whether the virus particles are intact or not, he added. “Current methods of detection are based on a form of PCR (polymerase chain reaction) but they have several drawbacks."
Norovirus can be transmitted by contact with infectious individuals, contact with contamination in the environment via utensils or work surfaces, or consumption of contaminated food.
Foods can become infected via two main routes. Firstly, oysters and other shellfish can become contaminated with norovirus originating from human sewage. Secondly, people infected with norovirus can transfer it onto foods they prepare.
The most common symptoms are nausea, vomiting and diarrhoea.
*To find out more about the project and the workshop, contact Dr Angus Knight at aknight@leatherheadfood.com or +44 (0)1372 822201