Risk Assessment of Rotavirus Infection in Surface Seawater from Bohai Bay,China

Dose-response data indicate that rotavirus (RV) may be one of the more infective agents among enteric viruses. The major limitation at present in the assessment of infection from rotavirus is lack of quantitative data on viral infectivity. In this work, an integrated cell culture and real-time quantitative polymerase chain reaction (ICC-qPCR) method and a Beta-Poisson model for risk assessment were employed. A set of 28 surface seawater samples was collected from December 2010 to September 2011 in Bohai Bay, China, to enable a seasonal risk assessment of infective RV at recreational beaches. Thirty-two percent of the samples were positive for rotavirus, and the estimated concentration range of infectious human rotavirus was 1 to 279 PFU/L. We further confirmed that the contamination of seawater with rotavirus was higher in autumn and winter, which was in reasonable agreement with the trend observed in a prior epidemiological study. Our preliminary risk assessment indicated the daily risk of illness at almost all the contaminated sites exceeded an acceptable threshold of marine recreational water quality (19 illnesses per 1000 swimmers). The detection method and dose-response model in the current work appear useful for evaluating pathogenic risks of seawater to vacationers and can inform management actions.