Sewerage systems are important nodes to monitor human enteric pathogens transmitted
via water. A quantitative virus survey was performed once a month for a year to understand
the seasonal profiles of noroviruses genotype 1 and genotype 2, enteroviruses, and
adenoviruses in sewerage systems. A total of 72 samples of influent, secondary-treated
wastewater before chlorination and effluent were collected from six wastewater treatment
plants in Japan. Viruses were successfully recovered from 100ml of influent and 1000ml
of the secondary-treated wastewater and effluent using the acid rinse method. Viruses
were determined by the RT-PCR or PCR method to obtain the most probable number for
each sample. All the samples were also assayed for fecal coliforms (FCs) by a double-layer
method. The seasonal profiles of noroviruses genotype 1 and genotype 2 in influent
were very similar, i.e. they were abundant in winter (from November to March) at a
geometric mean value of 190 and 200 RT-PCR units/ml, respectively, and less frequent
in summer (from June to September), at 4.9 and 9.1 RT-PCR units/ml, respectively.
The concentrations of enteroviruses and adenoviruses were mostly constant all the
year round, 17 RT-PCR units/ml and 320 PCR units/ml in influent, and 0.044 RT-PCR
units/ml and 7.0 PCR units/ml in effluent, respectively.