RESUMEN
Wastewater-based epidemiology (WBE) has emerged as a promising tool for monitoring the spread of COVID-19, as SARS-CoV-2 can be shed in the faeces of infected individuals, even in the absence of symptoms. This study aimed to optimize a prediction model for estimating COVID-19 infection rates based on SARS-CoV-2 RNA concentrations in wastewater, and reveal the infection trends and variant diversification in Shenzhen, China following the lifting of a strict COVID-19 strategy. Faecal samples (n = 4337) from 1204 SARS-CoV-2 infected individuals hospitalized in a designated hospital were analysed to obtain Omicron variant-specific faecal shedding dynamics. Wastewater samples from 6 wastewater treatment plants (WWTPs) and 9 pump stations, covering 3.55 million people, were monitored for SARS-CoV-2 RNA concentrations and variant abundance. We found that the viral load in wastewater increased rapidly in December 2022 in the two districts, demonstrating a sharp peak in COVID-19 infections in late-December 2022, mainly caused by Omicron subvariants BA.5.2.48 and BF.7.14. The prediction model, based on the mass balance between total viral load in wastewater and individual faecal viral shedding, revealed a surge in the cumulative infection rate from <0.1 % to over 70 % within three weeks after the strict COVID-19 strategy was lifted. Additionally, 39 cryptic SARS-CoV-2 variants were identified in wastewater, in addition to those detected through clinical surveillance. These findings demonstrate the effectiveness of WBE in providing comprehensive and efficient assessments of COVID-19 infection rates and identifying cryptic variants, highlighting its potential for monitoring emerging pathogens with faecal shedding.
Asunto(s)
COVID-19 , SARS-CoV-2 , Aguas Residuales , COVID-19/epidemiología , China/epidemiología , Aguas Residuales/virología , Humanos , Heces/virología , Betacoronavirus , Pandemias , Monitoreo Epidemiológico Basado en Aguas Residuales , ARN Viral/análisis , Esparcimiento de Virus , Carga ViralRESUMEN
A new thermoreversible and tunable hydrogel CS-M with high water content prepared by metal cation (M = Cu2+, Zn2+, Cd2+ and Ni2+) and chitosan (CS) was reported. The influence of metal cations on the thermosensitive gelation of CS-M systems were studied. All prepared CS-M systems were in the transparent and stable sol state and could become the gel state at gelation temperature (Tg). These systems after gelation could recover to its original sol state at low temperature. CS-Cu hydrogel was mainly investigated and characterized due to its large Tg scale (32-80 °C), appropriate pH range (4.0-4.6) and low Cu2+ concentration. The result showed that the Tg range was influenced and could be tuned by adjusting Cu2+ concentration and system pH within an appropriate range. The influence of anions (Cl-, NO3- and Ac-) in cupric salts in the CS-Cu system was also investigated. Scale application as heat insulation window was investigated outdoors. The different supramolecular interactions of the -NH2 group in chitosan at different temperatures were proposed to dominate the thermoreversible process of CS-Cu hydrogel.