Quantification and Genotyping of Norovirus in Aerosols from Wastewater Treatment Plants in Thailand

Norovirus and rotavirus are the major causes of acute gastroenteritis in humans worldwide. Due to their small size, these enteric viruses present in wastewater become aerosolized. The objective of this study was to assess the presence and concentrations of norovirus and rotavirus in aerosol samples collected from wastewater treatment plants (WWTPs) in Thailand. A developed method for concentrating viruses and performing molecular detection was used to determine naturally occurring enteric viruses. Of the 24 collected aerosol samples, 8 (33.3%) and 2 (8.3%) tested positive for norovirus RNA using RT-qPCR and RT-nested PCR, respectively. Based on RT-qPCR, norovirus GII RNA was detected more frequently in aerosol samples (7/24, 29.2%) compared to norovirus GI RNA (2/24, 8.3%). The norovirus GI concentrations were 9.8 × 10² and 3.2 × 10³ genome copies/m³. The norovirus GII concentrations ranged from 1.5 × 10² to 5.5 × 10³ genome copies/m³. RT-nested PCR detected norovirus GII RNA and the rare GII.21 norovirus strains were identified in the two aerosol samples. However, rotavirus RNA was not detected in any of the aerosol samples using either RT-qPCR or RT-nested PCR. This study highlights the quantification and genotyping of norovirus in aerosol samples generated from wastewater, suggesting a potential effect of airborne transmission for WWTPs workers.