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. 2024 Dec 7;17(1):6.
doi: 10.1007/s12560-024-09622-2.

Evaluation of Trends in Influenza A and B Viruses in Wastewater and Human Surveillance Data: Insights from the 2022-2023 Season in Italy

P Mancini  1 , D Brandtner  2 , C Veneri  1 , G Bonanno Ferraro  1 , M Iaconelli  1 , S Puzelli  2 , M Facchini  2 , G Di Mario  2 , P Stefanelli  2 , L Lucentini  1 , A Muratore  1 ; SARI network; E Suffredini  3 , G La Rosa  4
Collaborators, Affiliations

Evaluation of Trends in Influenza A and B Viruses in Wastewater and Human Surveillance Data: Insights from the 2022-2023 Season in Italy

P Mancini et al. Food Environ Virol. .

Abstract

Wastewater-based epidemiology (WBE) is a recognized, dynamic approach to monitoring the transmission of pathogens in communities through urban wastewater. This study aimed to detect and quantify influenza A and B viruses in Italian wastewater during the 2022-2023 season (October 2022 to April 2023). A total of 298 wastewater samples were collected from 67 wastewater treatment plants (WTPs) across the country. These samples were analyzed for influenza A and B viruses (IAV, IBV) using primers originally developed by the Centers for Disease Control and Prevention (CDC) for real-time PCR and adapted for digital PCR. The overall detection rates of IAV and IBV across the entire study period were 19.1% and 16.8%, respectively. The prevalence of IAV in wastewater showed a gradual increase from October to December 2022, peaking at 61% in December. In contrast, IBV peaked at 36% in February 2023. This temporal discrepancy in peak concentrations suggests different seasonal patterns for the two influenza types. These trends mirrored human surveillance data, which showed influenza A cases peaking at 46% in late December and declining to around 2% by April 2023, and influenza B cases starting to increase significantly in January 2023 and peaking at about 14% in March. IAV concentrations ranged from 9.80 × 102 to 1.94 × 105 g.c./L, while IBV concentrations ranged from 1.07 × 103 to 1.43 × 104 g.c./L. Overall, the environmental data were consistent with the human surveillance trends observed during the study period in the country. These results demonstrate the value of WBE in tracking epidemiological patterns and highlight its potential as a complementary tool to infectious diseases surveillance systems.

Keywords: Influenza virus; Surveillance; Wastewater; dPCR.

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Conflict of interest statement

Declarations. Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Fig. 1
Fig. 1
Distribution of WTPs in Italy. This map shows the locations of the 67 wastewater treatment plants (WTPs) across 20 Italian regions that were sampled as part of the environmental surveillance for influenza A and B viruses during the 2022–2023 influenza season
Fig. 2
Fig. 2
Results for environmental data over the seven-month period. This figure illustrates the detection of Influenza A and B viruses in wastewater samples across different regions of Italy from October 2022 to April 2023. Each color-coded region represents the presence of either Influenza A (in blue) or Influenza B (in red) viruses, based on the percentage of positive samples collected monthly (Color figure online)
Fig. 3
Fig. 3
Percentage of IAV and IBV positive samples over time: human and environmental data. This figure compares the percentage of positive samples for Influenza A and B viruses detected in wastewater and human samples over time from October 2022 to April 2023. The environmental data (solid lines) were collected monthly, while the human data (dashed lines) were collected weekly (data from the RespiVirNet Integrated Surveillance System)
Fig. 4
Fig. 4
Concentrations of Influenza A and B viruses in wastewater samples. The scatter plot illustrates the concentrations of Influenza A (blue dots) and Influenza B (red dots) viruses in wastewater samples collected from October 2022 to April 2023 (week 40–2022 to week 14–2023). The data are expressed in genomic copies per 100,000 population equivalent per day (Color figure online)
See this image and copyright information in PMC

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