Monitoring of hepatitis A virus in wastewater as an environmental surveillance tool in Córdoba, Argentina

Abstract

Due to hepatitis A virus (HAV) is a fecal-oral transmission pathogen, urban wastewater surveillance is considered a key tool to track the viral circulation trends over time in the population. The aim of this study was to assess HAV detection in wastewater samples from the city of Córdoba, Argentina, and to compare the results with the confirmed cases of hepatitis A illness reported during the same period.

Sewage samples were weekly collected from May 2020 to July 2021, from “Bajo Grande”, one of the wastewater treatment plants located in Córdoba city. Furthermore, sewage collectors of 7 neighborhoods in Córdoba city were weekly sampled from January 2021 to July 2022. Virus concentration was carried out using PEG6000 and NaCl, and automated RNA extraction and HAV molecular detection by RT-qPCR were performed afterward. Finally, the dataset on the total number of confirmed HAV infected cases reported during the same period was requested to the Epidemiology area of the Government of the Province.

Out of 748 samples analyzed, 49 were RNA-HAV+ (6.55%). One belonged to 2020 (2,04%), 8 to 2021 (16,3%), and 40 to 2022 (81,6%), both, from Bajo Grande and some neighborhoods in Cordoba city. HAV higher occurrence was in 2021 in the Pueyrredón neighborhood, particularly from April to July 2022, followed by Don Bosco and Marqués de Sobremonte. The number of HAV clinical cases notified was 1 in 2020, 3 in 2021, and 9 in 2022, mostly from March to May in adult patients (mean age 37 years old).

The HAV detection in wastewater confirms its circulation among the population of Córdoba, increasing its frequency simultaneously with the notification of clinical cases. Despite the low number of cases reported during 2020 and 2021, viral detection in wastewater during these years suggests a continuous silent circulation of HAV in the population, representing a potential risk for susceptible people. These results highlight the importance of wastewater-based epidemiology surveillance as a supplementary tool for clinical surveillance, to track the viral circulation trends dynamics in the population, and identify geographical hotspots of virus excretion.