Molecular Characterization and Phylogenetic Analysis of Enteroviruses and Hepatitis A Viruses in Sewage Samples, Northern Italy, 2016

Enteroviruses (EVs) and Hepatitis A Viruses (HAVs) are human pathogens with a wide spectrum of clinical manifestations. The monitoring of sewage samples enables to monitor the EVs and HAVs in circulation among the general population and recognize possible outbreaks. This study focused on the molecular characterization and phylogenetic analysis of the EVs and HAVs identified in 33 sewage samples collected every 15 days at the influent of a wastewater treatment plant located in Northern Italy from March to October 2016. According to the results of the molecular characterization, the most frequently identified viruses were Echovirus 6 (E-6), E-11 and HAV-IA. The phylogenetic analyses indicated the rapid genetic evolution of E-6 and E-1; noteworthy, most E-11 strains clustered with a strain isolated from a clinical sample collected in the same geographical area over the same period by our laboratory. Most of the HAV strains detected clustered with epidemic HAV-IA strains identified during the European hepatitis A outbreak that occurred in 2016-2017 affecting men who have sex with men (MSM). The detection of environmental HAV strains before and at the beginning of its spread amongst humans demonstrated that this outbreak could have been predicted by monitoring sewage samples. Moreover, conducting a genetic comparison between the HAV and EV strains identified in sewage and clinical samples may improve knowledge of viral epidemiology. EV and HAV molecular environmental surveillance may prove useful for identifying viral circulation and for issuing early warning alerts on possible outbreaks among the human population.