Persistence of human Aichi virus infectivity from raw surface water to drinking water

Abstract

Human Aichi virus 1 (AiV-1) is a water- and food-borne infection-associated picornavirus that causes gastroenteritis in humans. Recent studies on environmental waters showed a high frequency and abundance of AiV-1, suggesting that it might be an appropriate indicator of fecal contamination. We screened 450 surface and drinking water samples from a Tunisian drinking water treatment plant (DWTP) and the Sidi Salem dam for AiV-1 by real time reverse transcriptase PCR (RT-qPCR). The persistence of infectious particles was evaluated using an integrated cell culture approach coupled with quantitative molecular detection (ICC-RT-qPCR). In all, 85 (18.9%) water samples were positive for AiV-1 with viral loads ranging from 0.47 to 11.62 log₁₀ cp/L and a median of 4.97 log₁₀ cp/L, including 30/100 raw, 18/50 decanted, 14/50 flocculated, 9/100 treated, 1/50 tap, and 13/100 surface water samples. Of these, 15 (17.6%) samples contained infectious AiV-1 genotype A particles, including five raw, four decanted, one surface, three flocculated, and two treated water samples. Our data suggest that the persistence of infectious AiV-1 particles in environmental waters might represent a potential threat to public health. This study also indicates that the ICC-RT-qPCR is a practical tool for monitoring human waterborne viral risk in aquatic environments.IMPORTANCEHuman Aichi virus 1 (AiV-1) is a water- and food-borne infection-associated picornavirus that causes gastroenteritis in humans. Its high frequency and abundance in environmental waters would suggest that it might be an appropriate indicator of fecal contamination. The analysis of surface and drinking water samples from a Tunisian drinking water treatment plant (DWTP) and the Sidi Salem dam using an integrated cell culture approach coupled with a quantitative molecular detection (ICC-RT-qPCR) confirmed the persistence of infectious AiV-1 particles in samples at all stages of the treatment process, except in tap water. This suggests that the persistence of AiV-1 infectivity in environmental waters might represent a potential threat to public health. This study also indicates that the ICC-RT-qPCR is a practical tool for monitoring human waterborne viral risk in aquatic environments.

Keywords: AiV-1; Aichi virus; ICC-RT-qPCR; drinking water; infectious viral particles; surface water; virus quantification; wastewater.

Fig 1

Map of the drinking water network in northern Tunisia during the study period (adapted from Chabbi et al. [10]).

Fig 2

Average monthly number of cases of AiV-1 contamination of water and average environmental characteristics in Tunisia.

Fig 3

ICC-RT-qPCR virus quantification by water source.