cAlthough clinical epidemiology lists human enteric viruses to be among the primary causes of acute gastroenteritis in the human population, their circulation in the environment remains poorly investigated. These viruses are excreted by the human population into sewers and may be released into rivers through the effluents of wastewater treatment plants (WWTPs). In order to evaluate the viral diversity and loads in WWTP effluents of the Paris, France, urban area, which includes about 9 million inhabitants (approximately 15% of the French population), the seasonal occurrence of astroviruses and noroviruses in 100 WWTP effluent samples was investigated over 1 year. The coupling of these measurements with a high-throughput sequencing approach allowed the specific estimation of the diversity of human astroviruses (human astrovirus genotype 1 [HAstV-1], HAstV-2, HAstV-5, and HAstV-6), 7 genotypes of noroviruses (NoVs) of genogroup I (NoV GI.1 to NoV GI.6 and NoV GI.8), and 16 genotypes of NoVs of genogroup II (NoV GII.1 to NoV GII.7, NoV GII.9, NoV GII.12 to NoV GII.17, NoV GII.20, and NoV GII.21) in effluent samples. Comparison of the viral diversity in WWTP effluents to the viral diversity found by analysis of clinical data obtained throughout France underlined the consistency between the identified genotypes. However, some genotypes were locally present in effluents and were not found in the analysis of the clinical data. These findings could highlight an underestimation of the diversity of enteric viruses circulating in the human population. Consequently, analysis of WWTP effluents could allow the exploration of viral diversity not only in environmental waters but also in a human population linked to a sewerage network in order to better comprehend viral epidemiology and to forecast seasonal outbreaks.T he epidemiology of viral gastroenteritis is mainly evaluated through the use of clinical data. However, clinical data provide only a partial vision of the gastroenteritis viruses circulating in the human population. Indeed, many viral infections do not require specialized consultations or hospitalizations and so are not directly included in clinical statistics. As a consequence, these data sets offer a limited view of the diversity and occurrence of enteric viruses in the human population.Human astroviruses (HAstVs) and noroviruses (NoVs) are among the main causes of human acute gastroenteritis worldwide (1, 2). HAstVs and NoVs are nonenveloped viruses and have a positive-sense single-stranded RNA. The genome of HAstV is composed of three open reading frames (ORFs), and ORF2, encoding the capsid protein precursor, allows discrimination of eight genotypes of HAstV, HAstV-1 to HAstV-8 (3). The genome of NoV is also composed of three ORFs, and genotyping based on the genetic similarity of ORF2 and ORF3 allows discrimination of 9 genotypes of NoV genogroup I (NoV GI) and 22 genotypes of NoV genogroup II (NoV GII), which are the most common genogroups associated with human infections.HAstVs and NoVs are able to infect i...
