13 March 2013

Pesticides may be source of norovirus in food

by Will Parker

Outbreaks of norovirus (also known as the winter vomiting bug) are frequently linked to the consumption of fresh food, but identifying where the virus first came from is difficult, if not impossible. Now, a new study published in the International Journal of Food Microbiology indicates that contaminated water used to dilute pesticides may be how norovirus enters the food chain.

Noroviruses are a genetically diverse group of single-stranded RNA viruses of the Caliciviridae family. Human norovirus (hNoV) is highly contagious, causing vomiting and diarrhea. Outbreaks of norovirus infection often occur in closed communities, such as aged care facilities, camps, hospitals, prisons, dormitories, and cruise ships, where the infection spreads rapidly.

The new study, conducted by researchers from the Centre for Infectious Disease Control in the Netherlands, investigated whether contaminated water used to dilute pesticides could be a source of hNoV. Researcher Katharina Verhaelen notes that farmers use various water sources to dilute pesticides, including different types of surface water such as river water or lake water - sources which have often been found to harbor hNoV.

To test their theory, the researchers analyzed eight different pesticides diluted with hNoV contaminated water. The results showed that the infectivity of the norovirus was unaffected when added to the pesticides. "In other words, the pesticides did not counteract the effects of the [norovirus] contaminated water," said Verhaelen.

The researchers conclude that the application of pesticides on fresh produce may not only be a chemical hazard, but may also be a microbiological risk factor.

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Source: International Journal of Food Microbiology