Echoviruses (E) are a diverse group of viruses responsible for various pathological conditions in humans including aseptic meningitis, myocarditis, and acute flaccid paralysis. The detection and identification of echovirus genotypes in clinical samples is challenging due to its high genetic diversity. Here, we report the complete genome sequences of nine echoviruses, obtained by next-generation sequencing of 238 fecal samples from individuals with gastroenteritis in regions of Brazil. Detected viruses were classified into six genotypes: Three E1 sequences (BRA/TO-028, BRA/TO-069 and BRA/TO-236), one E3 (BRA/TO-018), one E11 (BRA/TO-086), one E20 (BRA/TO-016), two E29 (BRA/TO-030 and BRA/TO-193), and one E30 sequence (BRA/TO-032). Phylogenetic analysis indicated that the echoviruses E1 and E29 circulating in Brazil are divergent from strains circulating worldwide. The genotype diversity identified in our study may under-represent the total echovirus diversity in Brazil because of the small sample size and the restricted geographical distribution covered by the survey.

Yellow fever virus (YFV) continues to threaten human and wildlife populations in the Americas, yet its transmission at the forest–urban interface remains unclear. Here we integrate ground- and canopy-level mosquito surveillance, systematic monitoring of non-human primate carcasses and viral metagenomics to describe the dynamics of a sylvatic YFV outbreak in a 186-hectare Atlantic Forest fragment embedded within metropolitan São Paulo, Brazil, between 2017 and 2018. Our analyses reveal that transmission was primarily driven by a single genetic cluster introduced during a period of high abundance of the main vector, Haemagogus leucocelaenus mosquitoes. A near-complete hepatitis A virus genome was detected in a YFV-infected howler monkey, suggesting potential co-infections at the human–wildlife interface. Phylogenetic and epidemiological modelling estimated a basic reproduction number, R ₀ , for sylvatic yellow fever of 8.2 (95% CI 5.1–12.2), substantially higher than previous estimates for urban outbreaks. Our findings demonstrate that multisource surveillance could provide actionable early warnings in regions at risk for zoonotic spillover.

Squash mosaic virus (SqMV) is a phytovirus that infects great diversity of plants worldwide. In Brazil, the SqMV has been identified in the states of Ceará, Maranhão, Piauí, Rio Grande do Norte, and Tocantins. The presence of non-pathogenic viruses in animals, such as phytoviruses, may not be completely risk-free. Similarities in gene repertories between these viruses and viruses that affect animal species have been reported. The present study describes the fully sequenced genomes of SqMV found in human feces, collected in Tocantins, and analyzes the viral profile by metagenomics in the context of diarrhea symptomatology. The complete SqMV genome was obtained in 39 of 253 analyzed samples (15.5%); 97.4% of them belonged to children under 5 years old. There was no evidence that the observed symptoms were related to the presence of SqMV. Of the different virus species detected in these fecal samples, at least 4 (rotavirus, sapovirus, norovirus, parechovirus) are widely known to cause gastrointestinal symptoms. The presence of SqMV nucleic acid in fecal samples is likely due to recent dietary consumption and it is not evidence of viral replication in the human intestinal cells. Identifying the presence of SqMV in human feces and characterization of its genome is a relevant precursor to determining whether and how plant viruses interact with host cells or microorganisms in the human gastrointestinal tract.

Ten years after the onset of the largest yellow fever epidemic in the Americas, its transmission dynamics in neotropical primate hosts remain unclear. Using ground- and canopy-level entomology, systematic primate carcass surveillance, and metagenomics, we reconstructed a sylvatic YFV outbreak in a 186-ha Atlantic Forest remnant embedded within São Paulo metropolis. We found that, despite evidence of multiple introductions, transmission was dominated by a single genetic cluster that was introduced during the peak of abundance of Haemagogus leucocelaenus mosquitoes. Phylogenetic-informed modelling incorporating vector and host incubation periods and carcass-detection delays yielded a basic reproduction number, R0, of 8.2 (95% CI 5.1–12.2). Untargeted sequencing also uncovered a near-complete hepatitis A virus genome in a co-infected howler monkey (A. guariba), revealing bidirectional pathogen flow across the forest–urban interface. Integrating metagenomics, multi-source surveillance and climate-driven forecasting could provide cost-effective early warnings to guide pre-emptive vaccination and conservation efforts.

Canine distemper virus (CDV; Morbillivirus canis ) is a multi-host paramyxovirus primarily maintained in the order Carnivora. However, recent outbreaks in Neotropical primates suggest recurrent cross-species spillover into non-human primates. Between May and July 2022, seven marmosets ( Callithrix penicillata ) were found dead in urban and peri-urban areas of Montes Claros, Minas Gerais, Brazil. Viral metagenomic sequencing recovered two near complete CDV genomes directly from liver samples. Maximum likelihood and Bayesian phylogenetic analyses placed these genomes within the South American CDV lineage and supported at least three independent zoonotic introductions into Callithrix populations. Domestic dogs ( Canis lupus familiaris ) were inferred as the most likely source and the crab-eating fox ( Cerdocyon thous ) as a probable bridge host. Ancestral-state reconstruction identified a substitution at position 519 of the hemagglutinin (H) protein (R519I in the two primate clades and R519G in a singleton primate sequence). In silico modelling of the marmoset signaling lymphocytic activation molecule (SLAM) complex was consistent with a modest reorganisation of the receptor-binding head in the 519-substituted variants (ipTM = 0.82), generating a testable hypothesis that this residue may contribute to adaptation at the primate SLAM receptor interface and is associated with altered predicted docking orientation for the receptor. Together, these findings suggest that residue 519 is a candidate marker of CDV adaptation to Neotropical primates and emphasise the importance of integrating genomic surveillance with domestic dog vaccination efforts under a One Health framework to reduce the threat of CDV spillover to vulnerable wildlife populations.