Norovirus GII wastewater monitoring for epidemiological surveillance

Norovirus surveillance using case reports and syndromic detection often lags rather than leads outbreaks. To assess the timeliness of norovirus wastewater testing compared with syndromic, outbreak and search term trend data for norovirus, we quantified norovirus GII in composite influent samples from 5 wastewater treatment plants (WWTPs) using reverse transcription-digital droplet PCR and correlated wastewater levels to syndromic, outbreak, and search term trend data. Wastewater HuNoV RNA levels were comparable across all WWTPs after fecal content normalization. Norovirus wastewater values typically coincided with or led syndromic, outbreak, and search term trend data. The best correlations were observed when the wastewater sewershed population had high overlap with the population included by other monitoring methods. The provision of norovirus-specific measures and earlier detection of norovirus found using wastewater surveillance suggests that wastewater-based surveillance of human norovirus GII will enhance existing public health surveillance efforts of norovirus.