Two testing methods combined may be able to rapidly identify hepatitis A contamination in strawberries and green onions say researchers from Canada. Their findings appear in the September 2005 issue of the journal Applied and Environmental Microbiology.
Hepatitis A virus (HAV), which is endemic worldwide, is often transmitted to humans through contaminated food. Shellfish, fruits, and vegetables are commonly infected through contaminated water, surfaces, and food handlers and recent outbreaks have been specifically associated with strawberries and green onions. Detecting HAV in food has previously proven difficult due to the presence of inhibitory substances and low concentration of virus recovered.
In the study researchers combined real-time reverse transcription-PCR (a promising method for detecting HAV due to its sensitivity, specificity, speed, and ability to deliver quantitative data) and immunomagnetic separation (IMS) treatment (a method capable of addressing the limitations listed above) to detect for HAV in rinses from strawberries and green onions. Researchers were able to capture 20 times more HAV particles from both green onion and strawberry rinses receiving IMS treatment and complete the entire testing process within a six hour period.
"This study demonstrated for the first time the application of IMS combined with real-time RT-PCR for quantification of HAV in food rinses," say the researchers. "This procedure can be completed within six hours and has the potential to be applied for routine surveillance of HAV in fresh produce and environmental samples."
(X.C. Shan, P. Wolffs, M.W. Griffiths. 2005. Rapid and quantitative detection of hepatitis A virus from green onion and strawberry rinses by use of real-time reverse transcription-PCR. Applied and Environmental Microbiology, 71. 9: 5624-5626.)'"/>