Abstract
In urbanized areas where sewage system has been developed, noroviruses excreted from patients are collected in sewage treatment plants. Therefore, the concentration of noroviruses in sewage has been proposed as an indicator of gastroenteritis cases in the treatment area. In this study, we tested the applicability of norovirus monitoring in sewage as an early warning system of infectious gastroenteritis. Sewage samples were collected weekly from April 2013 to October 2015, and the temporal relation between norovirus concentration in sewage and the number of gastroenteritis cases reported in the study area was evaluated using cross correlation analysis. We also compared norovirus genotypes detected in sewage by pyrosequencing and those detected in clinical samples. As a result, significant correlation was observed between norovirus GII concentration in sewage and the number of gastroenteritis cases without a lag time (R = 0.57–0.72), implying that the concentration of noroviruses reflects the number of infected people when the sample was collected. Most of the norovirus genotypes or strains detected in stool samples were also found in sewage samples and they changed similarly over time during the study period. Considering that it takes one or two weeks for the number of gastroenteritis cases to be released to the public, norovirus monitoring in sewage is a promising alternative for the early warning system of gastroenteritis.
