This project is funded by the International Life Sciences Institute (ILSI).
Foodborne viral disease is an increasing problem worldwide. The globalization of our food supply means that we may not know the source of our fresh produce and cannot always control its quality. Fresh produce may not be as clean, green and healthy as we presume it is, especially when it is sourced from countries where general hygiene practices do not meet international standards. Instead, it may have been irrigated or washed in water containing human fecal material, or handled by field-workers or food-handlers with poor hygiene practices. In such situations, the produce probably will be contaminated with gastrointestinal disease-causing viruses.
The key factors influencing the risk of both pre-harvest and post-harvest contamination of fresh produce are water quality, field-worker hygiene, and food-handler hygiene. Soft fruits, herbs and salad greens consumed raw are at particular risk of viral contamination at the pre-harvest stage. The opportunities for both pre and post harvest viral contamination are great. Currently there are no accredited protocols for assessment of viral contamination of foods.
There is limited knowledge on how long the viruses can survive on fresh produce. Our research will add to this knowledge by investigating the survival and persistence of three human disease-causing viruses on fresh strawberries and ready-to-eat salad greens. We will also examine the effectiveness of washing strawberries and salad greens in cold and warm water to remove viruses. This can easily be achieved in both home and catering situations.
We will seed fresh produce with noroviruses, adenoviruses and hepatitis A virus, then store the produce at refrigeration temperatures for 15 days, and test samples for remaining virus every 3 days. For the washing experiments, we will wash produce in cold and warm water and measure the virus removal after each wash. Samples will be tested for presence of the 3 viruses by innovative molecular methods. Where possible, we will also measure the number of infectious viruses remaining on the produce by growing the viruses in cell culture systems. The results will be analysed using appropriate statistical procedures.
Our research will provide more information on virus survival and persistence on fresh produce and will assist with the development of appropriate intervention strategies to combat viral foodborne disease.