Purpose: The aim of this survey was to determine prevalence of NoV (GI and GII) and HAV in Australian grown fresh berries (strawberries and blueberries) and leafy greens (packaged and loose) at retail during 2013-14.
Methods: Sample size (n = 152 berries and n = 150 greens) was calculated based on the provision of a probability of 0.95 of detecting at least one positive if at least 2% of the samples were contaminated. NoV GI, NoV GII and HAV were determined by quantitative RT-PCR (ISO/TS 15216). E. coli, used as a fecal indicator, was determined by the MPN method (AS 5013.15).
Results: No HAV was detected in any of the samples. NoV GI was detected (5 to 50 copies/25 g) in three loose leafy green samples (2%). NoV GII was detected (1,000 copies/25 g) in one loose leafy green sample (0.67%), which had also tested positive for NoV GI. The estimated prevalence of E. coli (≥ 3 CFU/gm) was 0.66% and 10.67% in berries (1/152) and leafy greens (16/150), respectively. None of the virus positive samples were positive for E. coli, suggesting it is a poor indicator for the risk of enteric virus contamination.
Significance: No NoV and HAV were detected in packaged product at retail, suggesting good sanitary and process controls throughout the Australian berry and leafy green production chains. Despite a low prevalence of NoV, loose leafy greens may pose a higher risk to NoV related foodborne illness. The point of contamination was not determined in this study but may be associated with consumer handling.