Detection of genogroup IV norovirus in wastewater and river water in Japan

Aims: To test wastewater and river water in Japan for genogroup IV norovirus (GIV NoV). Methods and Results: Influent and effluent samples from a wastewater treatment plant and the Tamagawa River water samples were collected monthly for a year. The water samples were concentrated by the adsorption-elution method, using an HA electronegative filter with acid rinse procedure, followed by quantitative detection of GIV NoV using TaqMan-based real-time RT-PCR. Both wastewater and river water samples showed a high positive ratio of GIV NoV during winter and spring. The highest concentration in wastewater and river water was 6 center dot 9 x 104 and 1 center dot 5 x 104 copies l-1, respectively. Conclusions: Presence of GIV NoV in the environments demonstrates that not only GI and GII NoVs but also GIV strains are circulating and that routine monitoring of GIV NoV in water environments is recommended to understand its epidemics, environmental distribution and potential health risks. Significance and Impact of the Study: This is the first study providing quantitative data on the occurrence of GIV NoV in environmental water over a 1-year period.