The current COVID-19 pandemic has emphasized the vulnerability of communities living in the urban outskirts and informal settlements. The lack of reliable COVID-19 case data highlights the importance and application of wastewater-based epidemiology. This study aimed to monitor the COVID-19 trends in four vulnerable urban communities (slums and low-income neighborhoods) in metropolitan São Paulo by assessing the SARS-CoV-2 RNA viral load in wastewater. We analyzed 160 samples from May 2020 to June 2021 with weekly or fortnightly samplings. The samples were ultracentrifuged with glycine elution and quantified by N1/N2 SARS-CoV-2 RT-qPCR. The results of positivity were 100% (Paraisópolis, Heliópolis and Cidade Tiradentes) and 76.9% (Vila Brasilândia). The new case numbers of COVID-19, counted from the onset of symptoms, positively correlated with SARS-CoV-2 N1 viral loads from the two largest communities (p<0.001). SARS-CoV-2 infectivity was tested in Vero E6 cells after concentration with the two techniques, ultrafiltration (Centricon® Plus-70 10 kDa) and sucrose cushion ultracentrifugation, but none of the evaluated samples presented positive results. Next-generation sequencing (NGS) analysis from samples collected in March and August 2021 revealed the presence of the clade 20 J (lineage P.1) belonging to the most prevalent circulating variant in the country. Our results showed that wastewater surveillance data can be used as complementary indicators to monitor the dynamics and temporal trends of COVID-19. The infectivity test results strengthened the evidence of low risk of infection associated with SARS-CoV-2 in wastewater.

In this study, we characterized sequences similar to Marnaviridae obtained from water samples in the state of São Paulo, Brazil. Sixteen complete or nearly complete genomes were determined, all of them positive‐sense single‐stranded RNA, with lengths between 7074 and 10,198 base pairs, containing one or two open reading frames (ORFs). The amino acid sequences derived from the ORFs showed similarity and protein domains typical of the Marnaviridae family. Phylogenetic analysis based on RNA‐dependent RNA polymerase (RdRp) revealed clusters closely related to viruses that have not yet been classified by the International Committee on Taxonomy of Viruses (ICTV). Some sequences showed proximity to established genera such as Salicharnavirus , Locarnavirus , and Labynarvirus , while others formed three distinct clades, suggesting the presence of new genera. Furthermore, one sequence displayed an RdRp identity of less than 90% and a capsid identity of less than 75%, indicating that it represents a novel species related to Marnaviridae. These findings expand current knowledge of Marnaviridae diversity, contributing to a better understanding of evolutionary relationships and emphasizing the need for taxonomic reorganization.

During the Brazilian summer, from 29 December 2024, to 6 March 2025, a large cluster of acute gastroenteritis (AGE) outbreaks was reported along the coast of São Paulo State, Brazil, peaking in January 2025. Overall, 55 outbreaks involving 755 cases were officially notified, while more than 76,000 medical consultations for AGE were recorded across the region during the same period. A total of 50 stool samples were analyzed by RT-qPCR for group A rotavirus (RVA) and norovirus (NoV). NoV was detected in 27 samples (54.0%), confirming it as the main etiological agent, while RVA was identified in one sample (2.0%). Among NoV-positive cases, genogroup II (GII) predominated (59.0%), followed by genogroup I (GI) (19.0%) and mixed infections (22.0%). Genomic sequencing successfully genotyped 23 strains (95.8%), revealing six distinct genotypes. The recombinant GII.17[P17] was predominant (48.0%), followed by GI.3[P3], GI.3[P13], GI.5[P5], GII.4 Sydney_2012[P16], GII.3[P30], as well as mixed infections. No enteric viruses were detected in drinking water. However, seawater samples showed high concentrations of NoV GI and GII (up to 10⁴ GC L⁻¹) at beaches unsuitable for bathing. Wastewater surveillance revealed high viral loads, particularly NoV GII (up to 10⁸ GC L⁻¹), consistent with reported cases. To our knowledge, this is the first report in Brazil of a NoV-associated AGE outbreak investigated through an integrated approach combining clinical, environmental, and epidemiological surveillance data. Findings highlight genotype diversity and reinforcing the importance of integrated surveillance.

In this study, viral metagenomics was applied to identify viruses related to the Dicistroviridae family in freshwater samples collected from urban reservoirs of the state of São Paulo, Brazil. Through next-generation sequencing, five complete RNA genomes similar to Dicistroviridae were detected. These genomes range from 8.032 to 9.425 nucleotides in length, and each contains two open reading frames (ORFs) with conserved protein domains and internal ribosome entry sites (IRES) characteristic of Dicistroviridae. Phylogenetic and genetic identity analyses based on the amino acid sequences of the nonstructural (ORF1) and structural (ORF2) polyproteins suggest that these five genomes represent four putative novel species provisionally named Hydro virus 1 to Hydro virus 4. These findings enhance our understanding of the diversity and distribution of Dicistroviridae in aquatic environments.

Carbapenemase-producing Enterobacterales (CPE) pose a significant public health concern due to the limited therapeutic options and increasing dissemination outside clinical settings. Wastewater treatment plants (WWTPs) have been proposed as relevant environmental reservoirs for antimicrobial-resistant bacteria and mobile genetic elements. In this study, we performed genomic characterization of CPE strains recovered from raw wastewater samples from the influents of different WWTPs. Antimicrobial susceptibility testing revealed multidrug resistance, including coresistance to carbapenems and polymyxins, among Klebsiella pneumoniae , Enterobacter asburiae , and Enterobacter kobei strains. Whole-genome sequencing identified the convergence of the bla _KPC-2 and bla _GES-16 genes, as well as the presence of bla _GES-5 in E. kobei sequence type (ST) 540 strains. Moreover, the bla _KPC-2 gene was detected in K. pneumoniae strains belonging to high-risk clones ST11 (capsular types KL64 and KL15) and ST307 (capsular type KL102), and E. asburiae ST384. The bla _GES-5 and bla _GES-16 genes were associated with class 1 integrons, while the bla _KPC-2 gene was embedded within transposons (Tn 4401a , Tn 4401i , and Tn 3 -like) and insertion sequences (IS Kpn27 and IS Kpn6 ). Notably, genomic analyses and literature review demonstrated that the bla _GES-16 gene remains unique to Brazil. The putative pathogenic potential of carbapenem-resistant K. pneumoniae ST11 was also assessed. These findings support the environmental circulation of clinically relevant Enterobacterales genotypes and emphasize the potential role of WWTPs as conduits for CPE dissemination, if not adequately operated. Therefore, genomic surveillance in extra-hospital settings may contribute to a better understanding of antimicrobial resistance ecology and inform One Health mitigation strategies.