Assessment of the persistence and recovery of dengue virus RNA in urban wastewater: implications for Wastewater-Based Epidemiology.

Dengue virus (DENV) poses a growing global public health threat due to increasingly frequent and severe outbreaks. Moreover, epidemiological surveillance systems have limitations in the timely detection of outbreaks, highlighting the need for complementary tools such as Wastewater-Based Epidemiology (WBE). This study aimed to generate further information on the persistence and recovery of DENV RNA in urban wastewater to support its monitoring through WBE. Two experiments were conducted. In Experiment 1, the persistence of DENV RNA in urban wastewater incubated at 4, 25, and 35°C for 21 days was evaluated. A negative binomial mixed-effects regression model estimated temperature-specific decay coefficients of -0.67 (95 % confidence interval (CI): -0.74--0.59), -1.25 (95 % CI: -1.32--1.17), and -1.31 (95 % CI: -1.37--1.23) at 4, 25, and 35°C, respectively. The corresponding times required for a 90 % reduction in genomic copies concentration were 30.1 (95 % CI: 20.7-48.1), 5.3 (95 % CI: 4.7-6.1), and 4.8 (95 % CI: 4.3-5.4) days. In Experiment 2, the performance of four recovery methods was compared. Ultrafiltration showed the highest recovery efficacy (61 ± 8 %), followed by direct analysis (42 ± 10 %) and polyethylene glycol precipitation (7 ± 4 %). Skimmed milk flocculation yielded results below the limit of detection. In conclusion, DENV RNA persisted in urban wastewater for several days at environmentally relevant temperatures, and ultrafiltration achieved the highest recovery efficacy among the methods evaluated, supporting the application of WBE as a community surveillance tool for DENV.