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Oropouche virus infection: clinical spectrum, geographic expansion, and emerging maternal-fetal implications.

Oropouche virus (OROV), an emerging arbovirus of the genus Orthobunyavirus, has become a growing public health concern following its recent expansion across the Americas and its potential to cause severe clinical outcomes in maternal and child health. Although Oropouche fever has classically been described as an acute self-limited febrile illness, accumulating evidence indicates that OROV is associated with meningitis and fatal infection, as well as evidence of vertical transmission associated with adverse fetal outcomes, including microcephaly and other congenital abnormalities, spontaneous abortion, stillbirth, and neuropathological alterations resembling those observed in congenital Zika syndrome. The OROV presents two transmission cycles, namely sylvatic and urban, with Culicoides paraensis as its main vector. The absence of specific vaccines or treatments, together with the wide distribution of competent vectors and the possibility of sexual transmission, underscores the urgent need to strengthen epidemiological surveillance, elucidate the mechanisms of fetal pathogenesis, and develop effective prevention and control strategies to protect vulnerable populations.

Orthobunyavirus

Oropouche virus: viral evolution, epidemiological trends, and challenges for control.

PURPOSE OF REVIEW: In recent years, OROV has emerged as a significant public health threat beyond the Amazon region. Here we review current epidemiological, virological, clinical and ecological knowledge of OROV to inform health practitioners, public health authorities and the scientific community and to facilitate the development of effective control strategies for OROV. RECENT FINDINGS: We describe the epidemiological, virological, ecological and clinical characteristics of OROV, focusing on lessons from the recent expansion, and highlighting needs for control and management of this emerging arbovirus. SUMMARY: This review aims to inform health practitioners, public health authorities and the scientific community of the recent reemergence and expansion of OROV beyond the Amazon Basin. The ecology, epidemiology, virology of OROV and clinical presentations of OROV infection are discussed, and knowledge gaps are identified.

Humans

Surveillance of tick-borne viruses in the border regions of the Tumen River Basin: Co-circulation in ticks and livestock.

BACKGROUND: The unique eco-geographical patterns and climatic conditions of the China-Tumen River border region, combined with frequent cross-border tourism and trade activities, collectively establish this area as a recognized hotspot for tick-borne disease outbreaks. However, critical knowledge gaps persist regarding the eco-epidemiology of emerging tick-borne viruses and the distribution of their potential reservoir hosts within this trinational ecosystem spanning China, North Korea, and Russia. METHODS: We collected a total of 2,004 ticks from the study area, along with blood samples obtained from 42 sheep and 45 cattle. Following viral metagenomic analysis of the ticks, dual verification of target pathogens in all samples was performed using qRT-PCR and RT-PCR assays. Phylogenetic trees were constructed and nucleotide sequences were analyzed to delineate relationships between the obtained virus strains and reference sequences. RESULTS: Viral metagenomics identified three viruses in ticks: Dabieshan tick virus (DBTV), Songling virus (SGLV), and Yanggou tick virus (YGTV). PCR analysis detected DBTV exclusively in Hunchun ticks (minimum infection rates, MIR:4.73%) and YGTV in Antu specimens (MIR:0.97%). Conversely, SGLV was detected in ticks from all four regions, with MIR of 1.68% (Helong), 0.74% (Hunchun), 1.61% (Antu), and 4.79% (Longjing). Concurrently, SGLV was detected in 19 sheep blood samples from Longjing, yielding a positivity rate of 45.24%, while YGTV was identified in 13 cattle blood samples from Antu, with a positivity rate of 28.89%. Phylogenetically, the DBTV strain clustered with previously reported DBTV and Yongjia tick virus 1 isolates. Sheep-derived SGLV strains shared close evolutionary ties with tick-borne SGLV, whereas YGTV from cattle and ticks formed a distinct cluster with Russian strains but diverged into two branches from Chinese variants, suggesting evolutionary instability. CONCLUSION: These findings address critical knowledge gaps in the transmission dynamics and genetic diversity of emerging arboviruses while providing vital insights for developing cross-border surveillance strategies with significant public health implications.

Animals

Detection and phylogenetic characterization of Jingmen tick virus in Amblyomma mixtum ticks from Costa Rica.

UNLABELLED: Jingmenviruses are a group of segmented flaviviruses detected in arthropods and vertebrates that have attracted growing public health interest due to the recognition of some members as emerging human arboviral pathogens. As part of a study aimed at deciphering the virome of ticks of medical and veterinary importance in Costa Rica, we detected Jingmen tick virus (JMTV) in host-feeding Amblyomma mixtum ticks collected from horses. We assembled three complete genome segments and one partial segment from tick pools. Phylogenetic analyses revealed that JMTV from Costa Rica (JMTV Costa Rica) shares a common viral ancestor with JMTV viruses identified in ticks from the Caribbean and Latin America. Two distinct clades of Jingmenviruses were identified in the American continent, suggesting two distinct introductions: one from Europe/Asia and the other from Africa/Asia. Of note, JMTV Costa Rica falls in the same clade as viruses from Europe and Western Asia, including sequences found in humans. Our study constitutes the first detection of JMTV in Amblyomma mixtum. This tick species feeds on a wide range of hosts, including wildlife, domestic animals, and frequently parasitizes humans in Central America. Further research involving the detection of active and past infections by JMTV in humans and horses after tick bites is needed to evaluate the risk of spillover in Central America, including Costa Rica. IMPORTANCE: Jingmenviruses are flaviviruses detected in arthropods and vertebrates, reported in several countries worldwide. Some members cause disease and infections in humans; therefore, they are considered emergent human arboviruses. In Costa Rica and Central America, there is no information on tick-associated viruses or the role of ticks as putative vectors of viruses. Here, we report the first regional detection of Jingmen tick virus (JMTV) in Amblyomma mixtum ticks collected from horses. We assembled three complete and one partial viral segment from tick pools. Phylogenetic analysis revealed that the JMTV detected in Costa Rica is closely related to other detections from Latin America and the Caribbean and is located in the same clade as viruses reported in humans. Additionally, we detected two separate introductions of JMTV to Latin America. To determine whether this JMTV is an emergent arbovirus locally, research on past or active infections in humans is required.

Animals

Oropouche Virus Importation in Southern Brazil and Emerging Concern Calling for Enhanced Public Health Surveillance.

Oropouche virus (OROV), an arthropod-borne virus transmitted by Culicoides paraensis, is an endemic arbovirus that historically circulates mostly in the Amazon basin. Between 2022 and 2024, it reemerged as a more widespread public health concern in South America. We conducted a pooled-sample molecular surveillance study to understand the prevalence of Oropouche fever in Brazil's southernmost state. Over 18 months, we analyzed 4060 samples to monitor the virus emergence in the Rio Grande do Sul state. We detected the first human case of OROV in the state, and our phylogenetic reconstruction indicated a travel-related introduction from the Amazon region into Rio Grande do Sul. Despite the absence of local transmission, the invasion of Culicoides paraensis and enzootic circulation of the OROV in Rio Grande do Sul highlight the risk of Oropouche fever outbreaks in the region. We demonstrated that pooled-sample surveillance effectively monitors virus introduction during periods of low endemic circulation, serving as an essential active surveillance tool for the timely detection of virus emergence and enhancing public health preparedness. The multiple introductions of distinct OROV lineages into southern Brazil underscore the importance of genomic surveillance and public health strategies to monitor and mitigate arbovirus spread in the region.

Brazil

Global Genomic Surveillance.

Global genomic surveillance has emerged as a foundational pillar of public health in the twenty-first century, enabling real-time tracking of pathogen evolution and informing outbreak response. This chapter examines the strategic architecture of global genomic surveillance, focusing on its application to arboviruses such as chikungunya virus (CHIKV). It explores the integration of genomic data with epidemiological, clinical, and environmental information within a One Health framework, while addressing critical challenges in governance, equity, and interoperability. The discussion covers the entire genomic surveillance workflow, from sample collection and sequencing to bioinformatic analysis and phylogenetic inference, and highlights the transformative role of artificial intelligence (AI) in predictive surveillance. By analyzing global initiatives, operational barriers, and emerging technologies, this chapter underscores the necessity of sustainable, equitable, and interoperable genomic systems to proactively address current and future infectious disease threats.

Humans

Emergence and phylogeography of the dengue vector Aedes aegypti in Southeastern Iran.

BACKGROUND: Aedes (Stegomyia) aegypti (Linnaeus) is the primary vector of dengue, chikungunya, Zika, and yellow fever viruses. Its recent detection in southeastern Iran raises public health concerns about arbovirus spread to new regions. This study provides the first genetic and phylogeographic analysis of Ae. aegypti populations from Sistan and Baluchistan Province (SBP), Iran, to infer their origin and invasion pathways. METHODS: Mitochondrial COI and ND4 genes were analysed in newly collected Ae. aegypti specimens from border areas, ports, and urban centres of SBP. Haplotype network analyses were constructed using the TCS method in PopART, and phylogenetic analyses were conducted using global reference sequences. RESULTS: Iranian specimens comprised 7 COI haplotypes (n = 18) and 10 ND4 haplotypes (n = 17). COI phylogeny placed Iranian specimens into two main clades, while ND4 analysis distributed them across several derived clades, mostly clustering with lineages from Latin America (Brazil, Mexico) or Africa. One Iranian specimen showed a close relationship with a Saudi Arabian sequence (bootstrap: 98%) near the basal region. Combined COI + ND4 analysis revealed a monophyletic clade of Iranian specimens with a Sri Lankan specimen, distinct from other global lineages. The global COI network (n = 47) showed a star-like topology with a dominant haplotype 1 shared among 10 Iranian specimens. The ND4 network (n = 31) revealed a complex topology with 18 haplotypes, where a Saudi Arabian and one Iranian specimen (~30 mutational steps) possibly represented the peripheral root. CONCLUSIONS: Detection of diverse Ae. aegypti clades confirm establishment of this vector in southeastern Iran. Results support multiple introductions and genetic connectivity with Latin America, Africa, and South Asia, pointing to an emerging invasion corridor. Continued genomic surveillance and integrated vector monitoring are urgently needed to guide prevention strategies.

Animals

Protocol for Detecting and Sequencing Chikungunya Virus from Field-Collected Mosquitoes.

Arboviral diseases represent a major public health challenge, especially in tropical regions where environmental conditions may favor the proliferation and spread of mosquito vectors. Thus, early and accurate detection of chikungunya virus (CHIKV) in mosquito populations can be a valuable tool for effective surveillance of circulating variants and for identifying new viral introductions. Given the challenges of detecting arboviruses in field-captured mosquitoes, we describe an integrated workflow for CHIKV molecular detection and whole-genome sequencing. This protocol includes mosquito homogenization using a bead-based mechanical disruptor, RNA extraction using TRIzol reagent with minor modifications, molecular screening using CHIKV-specific RT-qPCR, and whole-genome amplification followed by sequencing on Illumina platforms. Despite the protocol being optimized for individual mosquitoes, it results in high-quality RNA suitable for both entomological surveillance and genomic analysis. As this protocol allows recovery of complete CHIKV genomes from mosquito specimens, it can serve as a basis for genomic epidemiology studies, enabling monitoring of viral diversity and lineage dynamics, and facilitating early detection of emerging variants to support timely and targeted public health interventions in endemic and at-risk regions.

Animals

Genetic diversity of Murray Valley encephalitis virus 1951-2020 identified via phylogenetic and evolutionary analyses.

Murray Valley encephalitis virus (MVEV) is a mosquito-borne orthoflavivirus endemic to Australia that can cause fatal neurological disease. The enzootic focus of MVEV is believed to reside in northern Western Australia (WA). We sequenced whole genomes of 70 MVEV sampled over 51 years, 1969-2020, from locations across Australia and Papua New Guinea (PNG) and identified greater MVEV diversity than previously recognized. Genotype 1 (G1) demonstrated greatest intra-genotype diversity and was predominant over the sampling period with sub-lineage G1B circulating in WA and seeding activity across Australia. G1A included viruses sampled across northern WA, as well as the Northern Territory (NT). A newly identified sub-lineage G1C circulated in northern WA in 1993 and was detected again in 2003. G2 viruses were distributed across the Kimberley and Pilbara regions of northern WA, and in the NT. Although no new G3 and G4 viruses, previously identified only in PNG, were detected in the present study, other MVEV originating in PNG clustered with G1A. We confirm MVEV is enzootic in northern WA, with transmission occurring more frequently and across a wider geographical area than previously recognised. Additionally, we identify evidence of regular genotype replacement that has occurred over many decades where the major genotypes G1 and G2 have circulated in northern WA since the late 1960s. We also show that WA MVEV likely seeded an MVE outbreak in Victoria in 1974, further supporting the notion that the enzootic focus of MVEV lies in northern WA. Recent increases in MVEV detections, MVE cases and deaths in WA and across Australia highlight the need for enhanced surveillance and more frequent sampling to understand viral origin and genomic diversity, to identify potential virulence motifs, and to understand the ecological drivers that determine emergence of MVEV in northern WA and movement of MVEV across the country.

Encephalitis Virus, Murray Valley

Genomic epidemiology of dengue virus 2 and 3 reveals repeated introductions and exportations of several lineages in Colombia.

Dengue fever, a major mosquito-borne viral disease, is transmitted by Aedes mosquitoes and poses a significant global health burden. Despite extensive research, the spatiotemporal dynamics of dengue virus (DENV) lineages in Colombia remain understudied. Here, we analyze 11,443 complete genome sequences from Colombia and the Americas to map the genomic epidemiology of DENV-2 and DENV-3. Phylogeographic reconstruction revealed multiple independent introductions and exportations of the DENV-2 II and III lineages, as well as the DENV-3 lineage III_C.2, underscoring Colombia's critical role as both a source and a sink of viral traffic within the Americas. Antigenic profiling demonstrated distinct clustering of emergent lineages in antigenic space, consistent with immune-escape-driven turnover. These results highlight the necessity of sustained, high-resolution genomic surveillance to guide targeted public health interventions and mitigate dengue transmission across the region.

Dengue Virus

Dengue and chikungunya vaccines past, present and future: implications for travelers.

PURPOSE OF REVIEW: Novel vaccines for dengue and chikungunya viruses offer new prevention options against two globally important arboviral diseases. This review summarizes recent developments in vaccine licensure, implementation, real-world experience and research priorities, with emphasis on implications for both endemic populations and travelers. RECENT FINDINGS: Of the three live-attenuated dengue vaccines licensed to date, TAK-003 is authorized in >40 countries and Butantan-DV in Brazil, while manufacturing of CYD-TDV is discontinued. Long-term and postmarketing data continue to refine understanding of serotype-specific protection, waning immunity, and rare adverse events.For chikungunya, two single-dose vaccines are licensed-a live-attenuated vaccine (VLA1553) and virus-like particle vaccine (PXVX0317). Uptake is guided by emerging safety and effectiveness data, with each platform offering potential advantages in different settings.Further data on long-term protection, safety, effectiveness, use in vulnerable populations and integration into outbreak management and immunization systems is anticipated. SUMMARY: Dengue and chikungunya vaccines are increasingly being used in immunization programs and pretravel consultations. Further real-world data are needed-particularly for seronegative dengue vaccine recipients and older, immunocompromised or medically at-risk adults. Research priorities include developing single-dose, nonlive dengue vaccines suitable for high-risk groups, understanding long-term chikungunya vaccine performance, and exploring broader flaviviral or pan-arboviral platforms.

Humans

SMART-RNA-Metavirome: a practical RNA metavirome platform compatible with high-throughput sequencing of both short and long reads.

BACKGROUND: The RNA virosphere's extensive diversity and its role in emerging infectious diseases underscore the importance of non-targeted sequencing for identifying unknown or rare pathogens, including co-infections. However, enriching low-abundance viral sequences in RNA metaviromics, particularly in the preparation of cDNA libraries and their compatibility with next-generation sequencing (NGS) and third-generation sequencing (TGS), remains challenging. Therefore, our objective is to develop and systematically assess a practical RNA metavirome methodology specifically tailored for the enrichment of low-abundance viral sequences within samples. METHODS: We developed the SMART-RNA-Metavirome platform, integrating SMART-9n library preparation with NGS and TGS technologies. Total RNA was extracted from two field-collected wild Aedes albopictus pools, along with one laboratory-infected Ae. albopictus pool harboring dengue virus (DENV). This RNA was subjected to reverse transcription using both this optimized protocol and random primer-based methods, followed by high-throughput sequencing on Illumina, Oxford Nanopore, and QitanTech Nanopore technologies. Welch's t-test was employed for comparative analysis of the subsequent RNA metavirome data, specifically to evaluate differences in viral species composition and abundance of viral reads between experimental groups. Furthermore, the effectiveness of this platform was systematically validated via RT-qPCR and SMART-RNA-Metavirome-based Oxford Nanopore sequencing across multiple sample types, including mosquito specimens from DENV-infected Ae. albopictus, serum samples from dengue patients and viral isolates of Japanese encephalitis virus (JEV) and Zika virus (ZIKV). RESULTS: The SMART-RNA-Metavirome platform has been systematically validated to excel in enriching the composition and diversity of the RNA virome (P = 0.04), providing sufficient coverage for the complete reconstruction of viral genomes. When employed in the detection of DENV-infected Ae. albopictus, clinical serum samples, and viral isolates of JEV and ZIKV, this technique exhibits a robust correlation with RT-qPCR (r2 > 0.95). Notably, it demonstrates exceptional sensitivity, ensuring sufficient coverage even in samples of DENV-infected Ae. albopictus with a Ct-value of 35.3, attaining an impressive 99.88% genome coverage. Furthermore, this platform possesses the capability to identify virus species and determine their serotypes. CONCLUSIONS: In our study, the SMART-RNA-Metavirome platform outperforms traditional methods, enriching RNA virome composition and diversity, enabling practical compatibility with both NGS and TGS technologies. It demonstrates significant proficiency in detecting both known and unknown arboviruses, even in low-titer samples such as those from wild mosquitoes and clinical sera. This platform facilitates comprehensive monitoring, risk assessment, and early warning of RNA virus transmissions, enhancing our understanding of RNA virome diversity and ecological patterns.

High-Throughput Nucleotide Sequencing

Detection and genomic characterization of a travel-associated ECSA lineage chikungunya virus infection in Mexico.

BACKGROUND: In 2013, chikungunya virus (CHIKV), a re-emerging Aedes-borne virus, was introduced into the Americas. This led to synchronous epidemics across the region associated mainly with the Asian lineage, which eventually subsided. Resurgent outbreaks have been recorded since, principally in South America, largely driven by the East-Central-South-African (ECSA) lineage. In 2025, more than 300,000 CHIKV suspected cases were reported in Brazil and Cuba. CASE SUMMARY: In November 2025, a healthy adult male traveling from Cuba arrived in Merida, Mexico, and shortly after presented febrile symptoms consistent with an arboviral infection. CHIKV infection was diagnosed by RT-qPCR. Though the infection was mild, the patient developed a rash on the abdomen and neck that persisted for up to a month, with further inflammation of the joints of the left leg. Phylogenetic analysis of the viral genome indicated placement within the ECSA lineage, clustering with other contemporaneous virus genomes sampled from Brazil that belong to a recently described clade II within the country, in which viral genomes from Cuba also cluster. CONCLUSION: We identify a travel-associated ECSA lineage CHIKV case in Mexico. This viral lineage has not previously been detected in the country. This finding highlights the risk for subsequent local transmission and is consistent with reports of the presence of this lineage in Cuba. Ten years since the last CHIKV epidemic in Mexico, strengthened surveillance is required to anticipate potential local outbreaks within the region.

ECSA