Effect of temperature and sunlight on the stability of human adenoviruses and MS2 as fecal contaminants on fresh produce surfaces

• Fresh produce is recognized as a main foodstuff related to large foodborne outbreaks.
• The effect of temperature on HAdV and MS2 stability on fresh produce is characterized.
• The effect of sunlight on HAdV and MS2 stability on fresh produce is characterized.
• The inactivation dynamics of HAdV and MS2 are evaluated by infectivity assays and qPCR.
• Times to achieve a reduction of 90, 99, 99.9 and 99.99% are estimated for each experiment.

Determining the stability, or persistence in an infectious state, of foodborne viral pathogens attached to surfaces of soft fruits and salad vegetables is essential to underpin risk assessment studies in food safety. Here, we evaluate the effect of temperature and sunlight on the stability of infectious human adenoviruses type 2 and MS2 bacteriophages on lettuce and strawberry surfaces as representative fresh products. Human adenoviruses have been selected because of their double role as viral pathogens and viral indicators of human fecal contamination. Stability assays were performed with artificially contaminated fresh samples kept in the dark or under sunlight exposure at 4 and 30 °C over 24 h. The results indicate that temperature is the major factor affecting HAdV stability in fresh produce surfaces, effecting decay between 3 and 4 log after 24 h at 30 °C. The inactivation times to achieve a reduction between 1 and 4-log are calculated for each experimental condition. This work provides useful information to be considered for improving food safety regarding the transmission of foodborne viruses through supply chains.