Background Wastewater-based epidemiology (WBE) has gained recognition as a valuable tool for monitoring enteric and respiratory viruses, such as poliovirus and SARS-CoV-2. However, its application to vector-borne diseases, including dengue virus (DENV), remains underexplored. This study investigates the feasibility of using WBE to detect DENV serotype 2 RNA during a local outbreak in Fano, central Italy, between August and October 2024. By 29 November, the outbreak, the largest recorded in Italy to date, resulted in 218 autochthonous cases reported with the last symptom onset date on 27 October. Methods Wastewater samples (n°=27) were collected twice a week from October 1 to October 30, during the epidemic's decline, from wastewater treatment plants in Fano and the nearby city of Pesaro. During the same period, 29 cases were reported. Results Four concentration methods were tested to optimize viral RNA recovery: a) Polyethylene glycol/sodium chloride precipitation b) Nanotrap® Magnetic Virus Particles c) Electropositive membrane filtration d) Solid fraction analysis. Among these, only solid fraction analysis successfully detected DENV-2 RNA in 9 of the samples with digital PCR demonstrating higher sensitivity than real-time PCR. Viral concentrations ranged from 6.1 × 10¹ to 7.9 × 10² genome copies per gram of solid material. This detection highlights the potential of environmental surveillance as a tool for monitoring dengue circulation in the population. However, the delayed start of sampling limited the chance of the study to track the epidemic in real-time and correlate wastewater viral concentrations with case trends. Conclusions The findings confirmed the presence of DENV RNA in wastewater during the outbreak, underscoring the potential of WBE as a complementary surveillance tool for vector-borne diseases. Future studies should refine methodologies to enhance detection sensitivity and reliability, and preparedness efforts should be made to ensure timely wastewater sampling in outbreak situations. Establishing proactive WBE systems could enable proper monitoring of emerging vector-borne outbreaks, informing public health responses and contributing to epidemic preparedness.
Wastewater monitoring of dengue virus RNA during a local outbreak in central Italy, August–October 2024 / Veneri, C.; Mancini, P.; Bonanno Ferraro, G.; Franco, A.; Iaconelli, M.; Brandtner, D.; Lucentini, L.; Venturi, G.; Marsili, G.; Del Manso, M.; Sacco, C.; Bella, A.; Riccardo, F.; Pezzotti, P.; Bolognini, L.; Magi, S.; Ballarini, E.; Grucci, A.; Suffredini, E.; La Rosa, G.. - (2025). ( ESCMID GLOBAL 2025 Vienna ).
Wastewater monitoring of dengue virus RNA during a local outbreak in central Italy, August–October 2024
P. ManciniCo-primo
;A. Franco;F. Riccardo;
2025
Abstract
Background Wastewater-based epidemiology (WBE) has gained recognition as a valuable tool for monitoring enteric and respiratory viruses, such as poliovirus and SARS-CoV-2. However, its application to vector-borne diseases, including dengue virus (DENV), remains underexplored. This study investigates the feasibility of using WBE to detect DENV serotype 2 RNA during a local outbreak in Fano, central Italy, between August and October 2024. By 29 November, the outbreak, the largest recorded in Italy to date, resulted in 218 autochthonous cases reported with the last symptom onset date on 27 October. Methods Wastewater samples (n°=27) were collected twice a week from October 1 to October 30, during the epidemic's decline, from wastewater treatment plants in Fano and the nearby city of Pesaro. During the same period, 29 cases were reported. Results Four concentration methods were tested to optimize viral RNA recovery: a) Polyethylene glycol/sodium chloride precipitation b) Nanotrap® Magnetic Virus Particles c) Electropositive membrane filtration d) Solid fraction analysis. Among these, only solid fraction analysis successfully detected DENV-2 RNA in 9 of the samples with digital PCR demonstrating higher sensitivity than real-time PCR. Viral concentrations ranged from 6.1 × 10¹ to 7.9 × 10² genome copies per gram of solid material. This detection highlights the potential of environmental surveillance as a tool for monitoring dengue circulation in the population. However, the delayed start of sampling limited the chance of the study to track the epidemic in real-time and correlate wastewater viral concentrations with case trends. Conclusions The findings confirmed the presence of DENV RNA in wastewater during the outbreak, underscoring the potential of WBE as a complementary surveillance tool for vector-borne diseases. Future studies should refine methodologies to enhance detection sensitivity and reliability, and preparedness efforts should be made to ensure timely wastewater sampling in outbreak situations. Establishing proactive WBE systems could enable proper monitoring of emerging vector-borne outbreaks, informing public health responses and contributing to epidemic preparedness.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
