Title : Environmental surveillance of enteric viruses: evaluation of urban wastewaters contamination in Sicily (Southern Italy)
Abstract:
Enteric viruses are responsible for sporadic or epidemic-related infections. They are typically transmitted via the fecal-oral route through person-to-person contact or through the consumption of contaminated food (shellfish, vegetables, etc.) or water. Their main health effect is gastroenteritis, but they can also cause hepatitis, conjunctivitis, respiratory symptoms, meningitis and chronic diseases. Among the enteric viruses we find: Noroviruses (NoV), considered the main etiological agents responsible for sporadic cases and epidemics of acute gastroenteritis (AGE) in all age groups, hepatitis A virus (HAV), hepatitis E (HEV).
Data on enteric virus contamination of wastewater in Sicily are not well known. The aim of this study was to investigate the prevalence of enteric viruses in Sicilian wastewater and shellfish. Since January 2022, the genomes of NoV, HAV and HEV have been searched for in urban sewage, collected by the Experimental Zooprophylactic Institute of Sicily (IZSSi) from three purification plants in the province of Trapani, during the systematic surveillance of SARS-CoV infection - 2 and its variants in wastewater, according to EU Recommendation 2021/472. Sewage samples were concentrated, following the method of Wu and co-workers, RNA was extracted from silica beads and subsequently purified.
NoV GI, NoV GII, and HAV were searched by a One-Step real-time RT-PCR assay for the well-conserved region at the 5' end of ORF2. HEV was tested using a One-Step Real-Time RT-PCR assay for the ORF3 region. 109 wastewater samples collected from January 4, 2022 to August 23, 2022 during monitoring programs were analyzed. A total of 76 fresh and frozen shellfish were also collected between January and August 2022, sampled by local public health inspectors in the framework of the national official monitoring activities. NoV GI and NoV GII RNA was detected in all (100%) urban sewages collected from January to August 2022 from Marsala (39), Mazara del Vallo (31) and Trapani (39). Of the 109 wastewater samples, 5 (4.59%, 95% CI 0.66-8.51%) were positive for HEV. No sample was found HAV positive. Only sewages collected From January to March 2022 from Trapani were contaminated by HEV. Only 3 Mytilus galloprovincialis of 76 shellfish samples (3.95%; CI95% -0.43%-8.32%) collected from March to August 2022 were positive NoV genome, one for NoV GI and two for NoV GII. No shellfish was found HAV or HEV positive.
Molecular surveillance of wastewater has clearly demonstrated that Noroviruses are widely present in environments. Residential wastewater can be a source of various types of contaminants, including a wide range of enteric viruses, HAV, NoV, and HEV selected for this study due to their epidemiological role as foodand waterborne pathogens. Wastewater monitoring, more than shellfish, is therefore an important epidemiological tool for assessing the spread of viruses and represents an effective method for implementing environmental surveillance.
Audience Takeaway:
• The study provides new information on the spread of enteric viruses in Southern Italy.
• The study indicates that residential wastewater can be a source of viral contaminants.
• Wastewater monitoring is an important epidemiological tool to detect viruses circulation at the community level.
