Quantitative detection of sapoviruses in wastewater and river water in Japan

Aims:  To detect sapoviruses at a wastewater treatment plant (WWTP) and in a river in Japan, quantitatively. Methods and Results:  Influent and effluent samples at a WWTP and river water samples were collected monthly for 1 year. The water samples were subjected to virus concentration using an HA electronegative filter, followed by quantification of sapoviruses using real‐time PCR. The concentration of sapoviruses in influent ranged from 2·8 × 10³ to 1·3 × 10⁵ copies per litre, showing a higher value in winter. Seven (58%) of 12 effluent samples were positive for sapoviruses, as were 23 (64%) of 36 river water samples collected from three sites along the Tamagawa River. Conclusions:  Sapoviruses were abundant in the influent even in the nonepidemic period, suggesting that sporadic and asymptomatic infections occur throughout the year. Increasing concentration of sapoviruses was discharged into the river during the epidemic period winter. Significance and Impact of the Study:  This is the first study demonstrating the quantitative detection of sapoviruses in aquatic environments.