Zika virus (ZIKV) remains a major global health concern, and no specific antiviral therapy is currently available. Amazonian natural bioactive compounds are promising candidates, but their therapeutic use is often limited by poor solubility and stability. We investigated the antiviral and immunomodulatory potential of Piper alatipetiolatum essential oil and zerumbone encapsulated in PEG-PCL nanoparticles (NPs) against ZIKV. Molecular docking was performed against the ZIKV NS5 methyltransferase to explore potential target engagement by the tested compounds. Antiviral activity was evaluated at key infection stages (adsorption, replication, and viral inactivation) using plaque-forming unit assays in Vero cells. Immunomodulatory effects were assessed by profiling cytokines in supernatants from nanocomposite-treated peripheral blood mononuclear cells (PBMCs) using high-sensitivity ELISA and ProQuantum assays. Docking analyses indicated that ishwarol B, a major constituent of Piper essential oil (along with 6-ishwaron and ishwarane), had the highest predicted affinity for the NS5 methyltransferase. Zerumbone-loaded nanoparticles (Z-PEG-PCL) showed the strongest stage-dependent anti-ZIKV activity, achieving 100% reduction during replication and inactivation and 60% during adsorption, whereas Piper essential oil-loaded nanoparticles (P-PEG-PCL) showed moderate effects (40% adsorption, 45% replication, and 58% inactivation). Z-PEG-PCL exhibited dose-dependent modulation, suppressing IL-6 and IL-8 at low concentrations while upregulating IL-8 at higher doses. Conversely, P-PEG-PCL consistently induced IL-6 but reduced IL-8 and IP-10. Although both systems attenuated TNF-α, they exerted antithetical effects on MCP-1, highlighting distinct mechanistic pathways for each nanoformulation. Overall, PEG-PCL nanoencapsulation enabled the delivery of Amazonian bioactives with combined antiviral and immunomodulatory effects, supporting this platform as a promising strategy for ZIKV-targeted interventions.

Infection by the Zika virus (ZIKV) results in a broad spectrum of disease ranging from mild to severe neurological complications. The clinical features of ZIKV human infection are similar in pregnant women compared with nonpregnant women, though symptomatic infection is more frequent during pregnancy. However, little is known about the profile of systemic immune mediators during ZIKV infection in pregnant women. To characterize immunological mediators in ZIKV infection during pregnancy, we measured the levels of circulating cytokines, chemokines, and growth factors by multiplex immunoassay in 32 pregnant women, categorized according to trimesters of pregnancy. ZIKV-infected pregnant women presented higher levels of the cytokines IL-1β, IL-6, TNF-α, IL-12, IFN-γ, IL-17, IL-1Ra, IL-4, IL-5, IL-9, and IL-10 than healthy women. Moreover, a set of pro-inflammatory biomarkers, including IL-1β, IL-6, TNF-α, IL-12, IFN-γ, CCL11, and G-CSF, showed significant increased levels in the gestational second trimester than in the first trimester, which remains elevated throughout the third trimester. In conclusion, our findings indicate that ZIKV human infection during pregnancy triggers a strong and broad systemic inflammatory response, and during the viral infection, their kinetics of the production varied according to the gestational age.

Background:Oropouche virus (OROV), an arbovirus causing acute febrile illness, was mostly restricted to the Amazon basin until 2023, when a reassortant lineage spread across Latin America. Increasing numbers of cases have subsequently been reported in extra-Amazonian regions of Brazil. However, follow-up and detailed clinical description is limited. This study aimed to describe viral, clinical, and epidemiological characteristics of OROV cases in the Brazilian states of Rio de Janeiro and Minas Gerais. Methods:This longitudinal study enrolled adults with OROV exposure. Clinical and laboratorial data were assessed, and serum, urine, and saliva samples were tested for OROV RNA and sequenced. Results:From December 2024 to May 2025, 55 OROV cases were recruited (median age: 46, 65% female). The novel OROV reassortant was confirmed by RNA sequencing. The acute phase was characterized by headache (87%), malaise (87%), fever (82%), myalgia (75%), and rash (45%). Recurrence of symptoms occurred in one-third of participants, including malaise (53%), fever (41%), arthralgia (41%), and chills (41%), but without resurgence of viral load. Viral RNA in serum and saliva was primarily detected in the first week of disease, and beyond the third week in urine. Conclusions:Cases appeared in clusters and rash was frequently observed. Symptoms returned after 1 week, indicating the importance of patient follow-up. Cases either lived near banana plantations or participated in recreational activities at waterfalls, raising concerns about ecotourism in the Atlantic Forest. Since OROV RNA was detectable in urine for a prolonged period, urine samples may be useful for diagnosis.

Background:After over a decade of minimal circulation, DENV-3 reemerged in Brazil in 2023, driven by the newly detected lineage 3III_B.3.2. Elucidating the patterns of DENV-3 spread and impact on public health, is critically important in the context of Brazil's hyperendemic dengue scenario. Here, we aimed to investigate the spatiotemporal dispersion of this new lineage and its epidemiological impact in Brazil. Methods:We generated 87 near-complete DENV-3 genomes, sampled in nine different Brazilian states, that were analysed with publicly available sequences. Phylogeographic reconstructions inferred introduction events and spatial dispersion of lineage 3III_B.3.2. In parallel, dengue cases notifications (2023-2025) were used to fit multiple logistic regression models assessing associations between DENV serotypes and severity, adjusting for demographic and spatiotemporal covariates. Findings:We detected at least 14 introductions of lineage 3III_B.3.2 into Brazil during 2023-2024, followed by diversification into six region-specific clades. Epidemiological analyses applied to the RT-qPCR dengue confirmed cases showed an adjusted odds ratios for severe dengue ranging from 1.24 to 1.71 for DENV-2 and from 1.47 to 1.94 for DENV-3, across different settings and using DENV-1 infection as the reference category. Sensitivity analysis to evaluate potential recent heterotypic infection among infants ≤2 years adjusted by confunders showed an association between DENV-2 and severe dengue, while DENV-3 estimates were not statistically significant. Interpretation:Our results reveal a dynamic pattern of multiple introductions and regionally structured spread of 3III_B.3.2, which may represent a general feature as a similar reconstructed history has also been observed for other DENV serotypes/lineages in Brazil. Although the association observed between DENV-2 and DENV-3 and dengue severity may be influenced by secondary infections, our findings underscore that the co-circulation of multiple serotypes contributes to more severe epidemic outcomes and emphasize the need for ongoing DENV genomic surveillance. Funding:DECIT, CGLAB, Fiocruz, CNPq, and FAPES.

BACKGROUND Oropouche virus (OROV), an arbovirus endemic to the Amazon region, has recently expanded into non-endemic areas including Rio de Janeiro State, Brazil. OBJECTIVE To characterise the spatio-temporal dynamics and ecological factors associated with OROV transmission in Rio de Janeiro during 2024-2025. METHODS We analysed OROV case-associated ecological factors and performed a phylodynamic analysis on 40 viral genomes, comprising 35 new and five published sequences, sampled from 15 municipalities across the state during 2024-2025. FINDINGS OROV cases showed significant positive correlations with forest area (r = 0.50, p < 0.0001), banana harvest area (r = 0.39, p < 0.01), and cassava harvest area (r = 0.29, p < 0.05); but these factors were autocorrelated, suggesting a confounded relationship. We identified two OROV sub-clades circulating in the Rio de Janeiro State. The OROVRJ/ES sub-clade was likely introduced into the Southern Fluminense region around January 2024, spread primarily by short (> 2 km, 50% of events) and mid-distance movements (2-9 km; 30%) with a mean dispersal rate of 0.3 km/day, and seed outbreaks in Metropolitan and Northwest Fluminense regions in 2025. The OROVES-I clade was likely introduced into Central Fluminense and Coastal Lowlands regions, later spreading to the Northern Fluminense region. MAIN CONCLUSIONS Following its introduction in early 2024, OROV persisted in Rio de Janeiro State by spreading through short-distance movements among municipalities with high forest cover and agricultural areas. The sustained multi-year OROV transmission in the Atlantic Forest biome highlights the potential for establishment of endemic cycles beyond the Amazon region and the need for enhanced surveillance in extra-Amazonian areas, where OROV will evolve in a different ecosystem.

Introduction Parvovirus B19 (B19V) infects erythroid precursor cells, compromising red blood cell production. This can trigger severe anemia and other hematological diseases in susceptible patients. However, data on B19V epidemiology in patients with hematological diseases are scarce, especially in the northern region of Brazil. The aim of this study was to estimate the prevalence of IgG and IgM antibodies against B19V, and to detect B19 DNA, in patients with hematological diseases undergoing Methods Plasma samples from 421 patients were subjected to enzyme immunoassay for the detection of anti-B19V IgG and IgM antibodies. Subsequently, all samples underwent real-time polymerase reaction for viral DNA detection. Results More than half (55.11%) of the study population was seropositive for IgG anti-B19 antibodies. Notably, women (prevalence ratio: 1.62; 95% CI: 1.10–2.41; p-value = 0.016) and individuals aged 60 and above (prevalence ratio: 7.72; 95% CI: 3.77–15.80; p-value = 0.016) showed the highest seroprevalence rates. Patients with thrombophilia, lymphoma, and anemia also exhibited elevated seroprevalence, with thrombophilia having the highest rate (prevalence ratio: 6.52; 95% CI: 1.78–23.88). Twelve patients were positive for IgM anti-B19, and the presence of B19V DNA was confirmed in two patients (0.46%). Conclusions Patients with hematological diseases, particularly thrombophilia, exhibit a high seroprevalence of B19V, indicating frequent prior exposure. However, recent infections and viremia are uncommon. The elevated seroprevalence among women and adults aged 60 and older suggests that these groups may be at greater risk. This underscores the need for enhanced epidemiological surveillance and targeted B19V testing to improve patient management.

Oropouche virus (OROV) was reported in Cuba in May 2024 and rapidly spread throughout the country. Here, among 147 reverse-transcription polymerase chain reaction-positive cases identified from May to July 2024, we sequenced 39 whole genomes of OROV. Phylogenetic analysis revealed that all sequences formed a monophyletic cluster nested within the reassortant lineage, named OROVBR-2015-2025, which has been circulating extensively in Brazil since 2023. Additional phylogeographic analyses demonstrated that the Cuban subclade probably originated from a single viral introduction from the Brazilian state of Acre in early February 2024, followed by cryptic circulation until its identification in May. The introduction probably occurred in the central region of the country, from which the virus spread and established secondary transmission hubs in the western and eastern regions. These findings underscore the capacity of OROV to spread well beyond South America, which was considered its endemic area of circulation.

We report a case of Guillain-Barré syndrome with visual impairment after confirmed Oropouche virus infection during the 2024 outbreak in Ceará, Brazil. Whole-genome sequencing revealed infection by a novel reassortant viral lineage (OROVBR_2025_2024), raising concern about the neurovirulence of this emerging orthobunyavirus strain.

Oropouche virus (OROV), historically endemic to the Amazon, had spread to nearly all Brazil states by 2024; Espírito Santo emerged as a transmission hotspot in the Atlantic Forest biome. We characterized the epidemiologic factors driving OROV spread in nonendemic southeast Brazil, analyzing environmental and agricultural conditions contributing to viral transmission. We tested samples from 29,080 suspected arbovirus-infected patients quantitative reverse transcription PCR for OROV and dengue, chikungunya, Zika, and Mayaro viruses. During March‒June 2024, the state had 339 confirmed OROV cases, demonstrating successful local transmission. Spatial analysis revealed that most cases clustered in municipalities with tropical climates and intensive cacao, robusta coffee, coconut, and pepper cultivation. Phylogenetic analysis identified the Espírito Santo OROV strains as part of the 2022-2024 Amazon lineage. The rapid spread of OROV outside the Amazon highlights its adaptive potential and public health threat, emphasizing the need for enhanced surveillance and targeted control measures.

BACKGROUND:The distribution of arboviruses in endemic regions is experiencing a significant shift, along with the re-emergence of Oropouche virus (OROV) as a significant pathogen, characterized by dynamic vector-borne transmission. Despite growing public health relevance, OROV remains insufficiently characterized, with limited comprehensive genomic and epidemiological data. This knowledge gap affects the accuracy of diagnostic approaches and limits the effectiveness of surveillance and control strategies. This study aimed to characterize the re-emergence of OROV in endemic regions, elucidate its epidemiological distribution, and clarify the epidemiological distribution of OROV and assess its impact on diagnostic strategies and surveillance for acute febrile illness. METHODS:Between January and July 2024, a total of 869 individuals with malaria-negative acute febrile illness were screened for dengue, Zika, and chikungunya viruses. Duplex RT-qPCR assays were subsequently employed to detect Mayaro and Oropouche viruses. Spatiotemporal and geospatial analyses were conducted to assess the distribution of OROV in relation to environmental factors. FINDINGS:Among the participants, 35 % tested positive for OROV, with cases predominantly concentrated in forest and riverine areas. Considering that the significant increase in the number of cases occurred in a short space of time, the results highlight the urgent need to strengthen genomic and epidemiological surveillance to tackle emerging arboviral threats.

Oropouche fever is a neglected tropical disease caused by the orthobunyavirus Oropouche virus (OROV). A recent OROV epidemic caused by a novel reassortant has seen infections across an expanded geographical range, with deaths of healthy adults plus vertical transmission leading to pregnancy loss. OROV research and epidemiology is hampered by a paucity of available tools for serology and molecular virology. We have purified recombinant OROV nucleoprotein and the spike region of the viral surface glycoprotein Gc. These antigens detect seroconversion following experimental infection of animals in indirect ELISA, confirming their antigenic authenticity. They stimulate the production of high neutralising antibody titres in animals, highlighting their promise as immunogens for vaccination. We developed a nanobody-based sandwich ELISA that can detect OROV antigens in human clinical serum samples with high efficiency, and we show that nanobodies directed against OROV Gc spike can potently neutralise infection by both historical OROV strains and the newly emerged reassortant. Our protein-based reagents will accelerate OROV research and highlight the utility of protein-based tools for future OROV vaccines and point-of-care diagnostic devices.

We report the first detection of Venezuelan Equine Encephalitis Virus (VEEV) in residents of Tabatinga, Amazonas, Brazil, a tri-border region with Colombia and Peru. Brazilian and Peruvian sequences clustered together, suggesting potential cross-border transmission. Our findings identify VEEV as an underrecognized etiology of acute febrile illness in the Brazilian Amazon.

Introduction: The abducens nerve (sixth cranial nerve) is a motor nerve that innervates the lateral rectus muscle, playing a key role in ocular abduction. Palsy of this nerve leads to convergent strabismus and diplopia. Common causes include strokes, trauma, inflammation, and infections, though in some cases, the etiology remains undetermined. With the emergence of COVID-19, neurological manifestations such as cranial neuropathies, including abducens nerve palsy, have been reported. Case presentation: We present a case of a previously healthy 48-year-old male diagnosed with SARS-CoV-2 infection who developed abducens nerve palsy in the left eye. Following the resolution of respiratory symptoms, strabismus persisted. Treatment with methylprednisolone was initiated, resulting in partial recovery within one week and complete resolution after three months. Conclusion: SARS-CoV-2-induced abducens nerve palsy can be reversible with conservative treatment using methylprednisolone. Early recognition and appropriate management are crucial for achieving a favorable prognosis.

Dengue fever, caused by the dengue virus (DENV), is the most important mosquito-borne disease impacting human health globally, it is particularly prevalent in tropical regions where Aedes vectors thrive. However, due to a recent expansion of the main dengue vectors to subtropical and temperate zones in the last decades there is an increasing human population at risk. Brazil is a global hotspot for dengue, accounting for 70% of all dengue cases reported worldwide in 2024. Noteworthy, dengue became endemic even in the southernmost Brazilian state of Rio Grande do Sul, which until recently had only imported cases. In this study, we integrated entomological, epidemiological, and high-resolution genomic data to investigate DENV transmission dynamics in Southern Brazil over nine years. From 2015 to 2023, we detected a partial to full invasion of the state municipalities by Aedes aegypti, with dengue cases increasing substantially from 2020 onwards. The suitability index for transmission effectively predict the intensity of the outbreaks in the region, providing a two-month lead time before the surge in cases, representing an interesting proxy to forecast the outbreak size in the next few years. Invaded municipalities that surpassed a given case incidence level also increased, and by 2023, nearly half of the municipalities of the state surpassed that threshold, suggesting that dengue became endemic in the region. By analyzing 665 newly generated DENV genomes, we observed persistent overwintering lineages driving seasonal outbreaks, with the Northwest and Metropolitan regions serving as the main transmission hubs for dengue spread in the state. These regions were also the first to experience the endemic establishment of dengue lineages, making them key areas for targeted control efforts to mitigate further local outbreaks and the virus spread to other regions. These findings underscore the expansion of DENV-affected areas and increasing outbreaks into temperate zones, likely driven by the spread of the vector, associated with increased infestation level of the vector and widespread viral transmission in an immunologically naive population. In this context, enhanced control efforts are critical to mitigate the dengue burden in previously non-endemic areas. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work was supported by Fundacao de Amparo a Pesquisa do Estado do Rio Grande do Sul (FAPERGS) FIOCRUZ 13/2022 REDE SAUDE-RS, grant process 23/2551-0000510-7 and FAPERGS 14/2022 - ARD/ARC, grant process 23/2551-0000852-1. A.B.G.V., T.G. and G.L.W. hold fellowships from Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (Grant processes 304476/2022-6, 310184/2023-1, and 307209/2023-7, respectively). R.S.S was supported by CNPQ and FAPERGS through the fellowship FAPERGS/CNPq 07/2022 - Programa de Apoio a Fixacao de Jovens Doutores no Brasil. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This project was approved by the Research Ethics Committee (CEP) at Escola de Saude Publica (SES-RS). Process number: CAAE: 67181123.1.0000.5312. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present work are contained in the manuscript - Figshare.

ABSTRACT Recombination plays a crucial role in the evolution of SARS-CoV-2. The Omicron XBB* recombinant lineages are a noteworthy example, as they have been the dominant SARS-CoV-2 variant worldwide in the first half of 2023. Since November 2023, a new recombinant lineage between Omicron subvariants XBB and BA.2.86, designated XDR, has been detected mainly in Brazil. In this study, we reconstructed the spatiotemporal dynamics and estimated the absolute and relative transmissibility of the XDR lineage. The XDR lineage displayed a recombination breakpoint in the ORF1a-coding region, and the most closely related sequences to the 5′ and 3′ ends of the recombinant correspond to JD.1.1 and JN.1.1 lineages, respectively. The first XDR sequences were detected in November 2023 in the Northeastern Brazilian region, and their prevalence rapidly surged from <1% to 25% by February 2024. The Bayesian phylogeographic analysis supports that the XDR lineage likely emerged in the Northeastern Brazilian region around late October 2023 and rapidly disseminated within and outside Brazilian borders from mid-November onward. The median effective reproductive number of the XDR lineage in Brazil during the initial expansion phase was estimated to be around 1.5, and the average relative instantaneous reproduction numbers of XDR and JN* lineages were estimated to be 1.37 and 1.29 higher than that of co-circulating XBB* lineages. In summary, these findings support that the recombinant lineage XDR arose in the Northeastern Brazilian region in October 2023, shortly after the first detection of JN.1 sequences in the country. In Brazil, the XDR lineage exhibited a higher transmissibility level than its parental XBB.* lineages and is spreading at a rate similar to or slightly faster than the JN.1* lineages.IMPORTANCEThis study highlights the emergence and rapid dissemination of the recombinant SARS-CoV-2 XDR lineage, derived from the Omicron lineages JD.1.1 and JN.1.1. The XDR lineage exhibited equivalent transmissibility to its JN.1* parental lineages and quickly spread across Brazil in late 2023. The findings underscore the critical role of real-time genomic surveillance in detecting novel variants with higher transmission potential. By utilizing phylogenetic and epidemiological methods, this research provides important insights into the molecular dynamics of XDR, which could inform public health responses and vaccine composition updates. The study’s significance lies in its ability to document the impact of recombination on viral evolution, offering valuable information to the field of virology and pandemic preparedness.

Oropouche virus (OROV) was reported in Cuba in May 2024 and rapidly spread throughout the country. Among 147 RT-PCR-positive cases identified from May to July, we generated 39 whole-genome sequences. Phylogenetic analysis revealed that all sequences formed a monophyletic cluster nested within the novel reassortant OROVBR-2015-2025, which has been circulating extensively in Brazil since the end of 2023. Additional analyses demonstrated that the Cuban sub-clade originated from a single viral introduction from the Brazilian state of Acre, probably in early February 2024, and circulated cryptically until its identification in May. The introduction likely occurred in the Central region of the country, from which the virus spread and established secondary transmission hubs in the Western and Eastern regions. These findings underscore the capacity of OROV to spread well beyond the Amazon region, which was considered its endemic area of circulation.

Background:The Oropouche virus (OROV) is an arthropod-borne virus that causes an acute febrile illness, like other arboviral diseases. In 2024, Oropouche cases sharply increased in several countries of the Americas, including Bolivia. Here, we investigate the origin and spread of OROV in the Bolivian Amazon region. Methods:Full-length OROV genomes from 34 positive samples collected in the three affected Bolivian departments during the 2024 outbreak were sequenced using an amplicon-based approach. Maximum Likelihood (ML) phylogenetic analyses of separate viral segments were conducted to identify the responsible viral lineage. Bayesian phylogeographic analysis of concatenated viral segments was used to reconstruct the viral spatiotemporal dispersion pattern within the country. Findings:The first Oropouche cases in Bolivia 2024 were reported using samples collected from the Pando department during mid-January, and the peak of Oropouche cases occurred in mid-April. The phylogenetic analysis of OROV genomes revealed that all cases detected in Bolivia belong to the novel reassortant OROV clade that drove the recent epidemic in Brazil. Our phylogeographic analysis detected at least two exportation events from the Brazilian state of Acre to the Bolivian municipalities of Guayaramerín and Riberalta, both located in the Beni department, with subsequent dissemination to municipalities of Pando and La Paz departments. Viral introductions likely occurred between early October and early November 2023, indicating a lag of approximately three months between the introduction of OROV and its detection. Interpretation:Our findings confirm that OROV spread at least twice from the western Brazilian Amazon to the neighboring Bolivian department of Beni in late 2023, successfully establishing regional transmission chains. These findings underscore the critical need for active OROV surveillance across the border Amazonian region between Brazil and Bolivia. They also confirm the potential for sustained OROV transmission within the Bolivian Amazon, highlighting the importance of preparedness for future outbreaks. Funding:This publication was in part supported by the Cooperative Agreement Number NU50CK000639 awarded to the Pan American Health Organization and funded by the Centers for Disease Control and Prevention.