Search Results (549)

The chikungunya virus (CHIKV) is an emerging alphavirus transmitted primarily by Aedes mosquitoes. This narrative review synthesised evidence from 56 mosquito-based records (34 field surveillance records and 22 laboratory vector competence records) published from January 2020 to June 2026. Aedes aegypti was the most frequently detected species, confirmed as CHIKV-positive in 22 of the 29 field studies that examined it, followed by Aedes albopictus (positive in nine of 12). Both species demonstrated consistent laboratory competence. Descriptive laboratory analysis showed mean infection, dissemination, and transmission values of approximately 76%, 77%, and 37% for Ae. aegypti, and 79%, 80%, and 47% for Ae. albopictus, respectively; these values are descriptive summaries across heterogeneous laboratory protocols and inconsistently reported genotypes. East/Central/South African–Indian Ocean Lineage of the chikungunya virus (ECSA-IOL) showed the highest mean transmission efficiency among genotype groups. In addition, CHIKV RNA was also detected in Culex quinquefasciatus, Psorophora spp., Wyeomyia spp., and other culicids in field studies, but laboratory evidence does not support these species as confirmed competent vectors. Other Aedes species, including Aedes vittatus, Aedes polynesiensis, Aedes koreicus, and Aedes japonicus, may have regional relevance but require further validation. Key evidence gaps include incomplete genotype reporting, limited virus isolation from positive mosquito pools, and inconsistent transmission metrics. Future preparedness for CHIKV emergence and spread requires integrated surveillance combining field detection, virus isolation, genomic sequencing, and standardised vector competence assays within an integrated surveillance framework. Full article

Background: Acute rheumatic fever (ARF) is a clinical syndrome triggered by group A streptococcal (GAS) infections and characterized by fever, carditis, and arthritis as its main manifestations. Diagnosis relies on the revised Jones criteria. We report a rare case of ARF diagnosed in Switzerland. Case Presentation: An 18-year-old woman presented to the emergency department five days after returning from a one-week stay in Egypt with intermittent fever and a transient sore throat, followed by migratory joint pain. Laboratory testing revealed leukocytosis, elevated C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). Chest X-ray, urine analysis, and (travel-associated) pathogen-testing (Epstein–Barr virus, Cytomegalovirus, human immunodeficiency virus, Malaria, Dengue, Zika, Chikungunya) were unremarkable. Blood cultures remained negative. Initially, a viral respiratory infection was suspected and symptomatic treatment established. Days later the patient was re-evaluated due to persistent symptoms. Leukocyte count (Lc) and CRP further increased and subcutaneous nodules appeared. The antistreptolysin-O (ASO)-titer was elevated more than three times higher than the normal upper limit and proofed serological evidence of a preceding streptococcal infection (GAS throat culture had not been performed). ARF was diagnosed according to the Jones criteria. Treatment with amoxicillin and a high dose of acetylsalicylic acid (ASA) led to a rapid clinical improvement. Secondary prophylaxis with depot penicillin (benzathine penicillin G; 1.2 million units; once monthly) was initiated to prevent rheumatic heart disease. Conclusions: This case highlights a rare occurrence of ARF following travel to Egypt, with probable acquisition of group A streptococcal infection during the trip. It emphasizes consideration of ARF even in Western countries with low ARF-prevalence if clinical history is suggestive. Early recognition and initiation of antimicrobial and anti-inflammatory therapy is crucial to prevent cardiac involvement. To the best of our knowledge, this represents one of the first cases diagnosed in Switzerland in the past 20 years. Full article

Background: Chikungunya virus (CHIKV) is a re-emerging alphavirus that has caused millions of cases worldwide, yet its molecular epidemiology in Saudi Arabia remains poorly understood. This study integrates bioinformatic analysis of the envelope gene (E1) gene sequences from Saudi isolates with global genotypes to characterize circulating lineages, selection pressures and stability effects of endemic mutations. Methods: A total of 109 CHIKV E1 sequences (1155 bp) representing the East/Central/South African (ECSA), Asian, and West African genotypes were retrieved from GenBank and GISAID. Phylogenetic relationships were reconstructed using maximum likelihood (IQ-TREE). Codon-based selection analyses were performed with MEME, FEL, SLAC, and FUBAR. The structural effects of nine missense mutations were assessed using DynaMut and consensus predictors (DUET, mCSM). Results: All seven Saudi isolates clustered within the ECSA-Indian Ocean Lineage (IOL) subclade with strong bootstrap support (≥95%). Short branch lengths among Saudi strains indicated recent common ancestry and limited local divergence, suggesting possible repeated introductions or limited local circulation. No codon showed robust evidence of positive selection across multiple methods. However, episodic diversifying selection was detected at codon 99 (MEME, p = 0.01), while pervasive purifying selection acted on numerous sites (e.g., codons 135, 307, 344; strong signals across FEL, SLAC, and FUBAR). A single conserved N-linked glycosylation site was present at residue 141 (NITV motif) in all Saudi and most global strains. Three mutations unique to or prominent in Saudi isolates (N20H, L136F, A249T) were identified; consensus stability predictions (DUET) classified them as destabilizing. Conclusions: Saudi CHIKV strains belong exclusively to the ECSA-IOL lineage and exhibit strong purifying selection on the E1 gene, consistent with functional constraints on this essential fusion protein. The identified Saudi-associated mutations appear to be non-adaptive, tolerated changes. These findings underscore the value of continued genomic surveillance to monitor potential adaptive evolution, particularly in the context of mass gatherings and competent Aedes vectors. Full article

Background/Objectives: The lack of effective antiviral therapies for many viral infections highlights the need for the development of new antiviral agents. The broad antiviral effects of glycopeptide antibiotics (GPAs) and their derivatives have been previously described. In our studies, we investigated the in vitro viral inhibitory activity of newly synthesized GPA derivatives against Zika virus (ZIKV), chikungunya virus (CHIKV), o’nyong-nyong virus (ONNV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methods: Antiviral activity (EC50) and cytotoxicity (CC50) of the active compounds were determined using cell-based assays. The mechanism of action of the lead compound was investigated using binding and entry assays, cell-free virion pre-incubation, a virion destabilization assay, a liposome-based capsid protection assay, and molecular docking analysis. Results: Seven of the compounds were able to inhibit ZIKV and two compounds inhibited all four tested viruses. Among them, a teicoplanin pseudoaglycone derivative, compound 7, showed the strongest antiviral activity, inhibiting all four viruses at low micromolar concentrations. Mechanistic studies demonstrated that compound 7 acts during an early stage of ZIKV infection and inhibits low-pH-triggered virus–liposome fusion. Molecular docking analysis suggested potential interactions between compound 7 and the viral envelope protein that could interfere with the conformational rearrangements required for membrane fusion. Conclusions: The present findings demonstrate that hydrophobic GPA derivatives, particularly compound 7, exhibit promising broad-spectrum antiviral activity in vitro. Whether similar mechanisms contribute to the antiviral activity against other viruses remains unknown. The studied GPA derivatives are promising candidates for further pre-clinical and clinical development as broad-spectrum antivirals. Full article

Chikungunya virus (CHIKV), traditionally recognized as a mosquito-borne alphavirus that causes febrile illness and debilitating arthralgia, has increasingly been associated with atypical organ involvement, including respiratory manifestations. These observations raise important questions regarding whether respiratory symptoms reflect severe systemic disease or signal previously underappreciated respiratory exposure routes. This review aimed to synthesize current evidence on respiratory complications of CHIKV infection and to evaluate the plausibility of respiratory or aerosol-associated transmission. A systematic literature search of PubMed, EMBASE, and MEDLINE (Ovid) identified five eligible studies spanning clinical virology, outbreak surveillance, epidemiology, and experimental aerosol models. Across human studies conducted in India, Réunion Island, Puerto Rico, and Brazil, respiratory presentations—including pneumonia, dyspnea, and respiratory failure—were uncommon but consistently associated with increased hospitalization and mortality risk. Respiratory symptoms generally arose in the context of respiratory viral coinfections, systemic inflammation, or cardiopulmonary decompensation rather than primary viral tropism for the respiratory tract. Only one non-human primate study directly evaluated aerosol exposure, demonstrating that cynomolgus macaques could be infected via inhaled CHIKV, confirming biological plausibility but showing no evidence of enhanced respiratory pathology. Importantly, no epidemiologic data support human-to-human airborne or droplet transmission. Collectively, available evidence indicates that respiratory involvement serves as a marker of disease severity rather than a transmission route. Nonetheless, rare aerosol-acquisition events in laboratory settings underscore the need for continued vigilance, strengthened surveillance, and re-evaluation of respiratory risks as climate change and viral evolution expand CHIKV’s global footprint. Full article

Two chikungunya (CHIKV) vaccines have now been licensed, but the human clinical evidence base remains fragmented across vaccine platforms, populations, follow-up periods, and safety settings, complicating product-specific interpretation of durability and benefit–risk. We conducted a PRISMA-ScR–guided scoping review of human CHIKV vaccine evidence indexed in PubMed, Embase, and Web of Science from January 2000 to June 2026. After screening 890 records, we included 77 sources of evidence and mapped them at both the record level and the candidate/product level. The included evidence clustered around a limited number of vaccine programs, including TSI-GSD-218, VRC-CHKVLP059-00-VP/PXVX0317/Vimkunya, MV-CHIK/V184, VLA1553/IXCHIQ, ChAdOx1 Chik, and mRNA-1388/VAL-181388. Late-stage and post-authorization evidence was concentrated mainly in VLA1553/IXCHIQ and PXVX0317/Vimkunya, whereas viral-vector and mRNA candidates remained largely restricted to early-phase adult studies. Evidence has expanded to adolescents and adults aged ≥65 years for selected products but remains limited or product-specific for children, pregnant individuals, immunocompromised populations, and medically complex older adults. Short-term trial safety data were characterized primarily by mild or moderate local and systemic reactogenicity, while post-authorization safety evidence remains recent and concentrated in licensed products. This scoping review provides a structured evidence map for CHIKV vaccine development and highlights priorities for standardized immunogenicity assessment, longer-term durability data, broader population representation, endemic-region effectiveness studies, and continued post-marketing surveillance. Full article

Climate change is reshaping the epidemiology of vector-borne diseases in Europe by altering the ecological conditions that determine vector survival, seasonal activity and pathogen transmission. Rising temperatures, milder winters, prolonged warm seasons and changing precipitation patterns are increasing the suitability of parts of Europe for competent mosquito, tick and sandfly vectors. These changes, combined with human mobility and land-use change, increase the probability that imported pathogens encounter permissive conditions for local transmission. This Opinion article examines autochthonous vector-borne disease transmission in Europe, using dengue as a sentinel example of a wider climate-sensitive transition. We discuss how imported viraemic cases, established competent vectors, vector–host contact and delayed clinical recognition can converge to enable local outbreaks. Beyond dengue, we consider West Nile virus, chikungunya, tick-borne encephalitis, leishmaniasis and Crimean–Congo haemorrhagic fever as examples of a broader and increasingly heterogeneous European risk landscape. We argue that the public-health impact of this transition is shaped not only by vector expansion, but also by gaps in surveillance integration, diagnostic readiness, workforce preparedness and One Health coordination. Strengthening climate-informed surveillance, rapid laboratory capacity, frontline clinical awareness and cross-sectoral response systems will be essential to prevent repeated introductions from becoming sustained public-health challenges. Full article

Dengue virus (DENV) and chikungunya virus (CHIKV) co-circulate in many regions and present with overlapping clinical features, which complicate accurate diagnosis and disease management. This study develops an integrative transcriptomic framework to identify robust host gene signatures that distinguish between dengue, chikungunya, and healthy states. Publicly available RNA sequencing (RNA-seq) datasets derived from human blood samples were analyzed using a cross-validation design to ensure robustness and prevent information leakage. Differential expression analysis was performed independently within each dataset using the Generalized Linear Models with Quasi-Likelihood F-tests and Magnitude–Altitude Scoring (GLMQL-MAS) framework, followed by Cross-Magnitude–Altitude Scoring (Cross-MAS) integration to identify shared and virus-specific gene signatures. A strict consensus approach across folds was applied to derive reproducible gene sets. These signatures were used for dimensionality reduction and multinomial logistic regression to evaluate classification performance. A small subset of selected genes showed strong discriminative performance within the cross-validation framework, with test balanced accuracy reaching 0.97, which improved upon models using all genes. Biologically, both infections exhibited a shared antiviral response characterized by interferon signaling and innate immune activation. However, distinct virus-specific patterns were identified. Dengue infection was associated with cell-cycle and DNA replication pathways, while chikungunya infection showed stronger enrichment of inflammatory and immune signaling pathways, including NF-kappaB and Toll-like receptor signaling. Overall, this study provides a cross-validation-based framework for integrative transcriptomic analysis and identifies compact, reproducible host-response signatures with strong discriminative signals in the analyzed cohorts. These signatures require validation in larger independent cohorts before any clinical or diagnostic application. Full article

In 2025, tropical medicine was shaped by advances in diagnostic technology, expanding arboviral epidemics, rapid progress in filovirus vaccine development, evolving regulatory responses to newly licensed vaccines, and translational breakthroughs addressing neglected tropical diseases. This review discusses five select developments that significantly influenced clinical practice and global health policy over the past year, highlighting the implications of each for clinicians, researchers, and public health systems. Full article

O’nyong-nyong virus (ONNV) is a mosquito-borne alphavirus responsible for large-scale epidemics in sub-Saharan Africa. As the closest evolutionary relative of Chikungunya virus (CHIKV), ONNV shares substantial genetic similarity and overlapping clinical manifestations with CHIKV. Mechanistic understanding of ONNV infection has therefore largely been extrapolated from CHIKV rather than directly established. However, ONNV exhibits distinct biological features, including predominant transmission by Anopheles mosquitoes and a clinical presentation characterized by prominent lymphadenopathy with limited acute joint edema. These distinctions underscore the need for an integrated synthesis of experimentally validated determinants of ONNV infection. In this review, we summarize current evidence on molecular and immunological factors regulating ONNV infection in mammalian hosts and mosquito vectors. We first discuss species-specific viral clearance, host dependency factors, intrinsic antiviral restriction mechanisms, protective innate immunity, inflammatory pathology, and mechanism-informed therapeutic strategies in mammalian hosts. We then examine stage-specific immune regulation in Anopheles mosquitoes, emphasizing mechanisms that constrain viral replication while permitting persistent infection and transmission. Finally, we discuss nsP3-dependent vector specificity and the potential contribution of alternative mosquito species to ONNV ecology. Together, this review provides an integrated framework for understanding how host factors, immune responses, and vector-specific adaptations shape ONNV infection, pathogenesis, and transmission. Full article

Background/Objectives: Arboviral diseases transmitted by Aedes mosquitoes, including Dengue (DENV), Zika (ZIKV), and Chikungunya (CHIKV), represent a major public health challenge in tropical regions. Their clinical similarity complicates differential diagnosis, particularly in settings of viral co-circulation, and may lead to underdiagnosis. The objective was to detect acute dengue infection and assess serological evidence of Chikungunya and Zika virus exposure among patients with acute febrile syndrome and clinical suspicion of dengue in the department of Córdoba, Colombia. Methods: A prospective descriptive study was conducted between 2023 and 2024 in healthcare institutions in Montería and Sahagún. Serum samples were analyzed by ELISA to detect DENV NS1 antigen, anti-CHIKV IgM, and anti-ZIKV IgG antibodies. Sociodemographic, clinical, and laboratory variables were described, and the association between prior ZIKV infection and dengue severity was assessed. Results: Ninety patients were included. Isolated laboratory marker detection was observed for DENV NS1 antigen in 36.7% (33/90), anti-ZIKV IgG in 30.0% (27/90), and anti-CHIKV IgM in 2.2% (2/90); combined arboviral markers were identified in 22.2% (20/90), and 8.9% (8/90) had no detectable markers. Among NS1-confirmed dengue cases (n = 47), 61.7% (29/47) were classified as dengue with warning signs. Anti-ZIKV IgG detection was not associated with dengue clinical classification (p = 0.989), although platelet counts were lower in IgG-positive cases (p = 0.037). Conclusions: The findings support laboratory-supported diagnosis and integrated acute febrile illness surveillance in Córdoba, including locally adapted vector control, in a setting of arbovirus co-circulation with overlapping laboratory markers. Full article

Arboviral diseases are emerging as important public health threats in Saudi Arabia, driven by rapid urbanization, climate variability, the expansion of Aedes aegypti populations, international travel, and large-scale religious mass gatherings. Dengue virus remains the most established arboviral infection in the Kingdom, particularly in the southwestern regions such as Jazan and the western urban centers of Makkah and Jeddah, where ecological and climatic conditions are conducive to sustained vector survival and transmission. This review synthesizes current evidence on the epidemiology, vector ecology, climatic determinants, diagnostics, and prevention strategies of arboviral diseases in Saudi Arabia. Particular attention is paid to the impacts of rising temperatures, changes in rainfall patterns, urban heat island effects, population mobility, and cross-border movement on vector expansion and disease emergence. The review also identifies gaps in surveillance, diagnostics, insecticide resistance monitoring, and integrated vector management programs. Emerging preparedness strategies include climate-informed early warning systems, Geographic Information System-based risk mapping, multiplex molecular diagnostics, genomic surveillance, and community-based vector control. The review emphasizes the importance of implementing a One Health approach that combines data on humans, the environment, entomology, and climate. Currently, sustained endemic transmission of chikungunya and Zika viruses has not been conclusively demonstrated in Saudi Arabia, but increased environmental suitability and connectivity with other areas highlight the need for proactive surveillance and preparedness. Full article

Background/Objectives: Arboviruses including dengue virus (DENV), Zika virus (ZIKV), chikungunya virus (CHIKV), yellow fever virus (YFV), and West Nile virus (WNV) co-circulate across the Americas, generating overlapping febrile syndromes that challenge etiological diagnosis based solely on clinical criteria. Cartridge-based multiplex molecular platforms offer potential for decentralized testing in hyperendemic settings, yet independent real-world evaluations of their clinical and analytical performance remain limited. Methods: A retrospective two-phase analytical study was conducted. Phase 1 assessed clinical diagnostic accuracy for dengue using 163 de-identified serum samples classified using a composite reference standard consisting of Panbio NS1 ELISA reactivity (≥11 Panbio units) combined with compatible clinical and epidemiological data, operationalized in accordance with the PAHO 2023 laboratory confirmation algorithm for dengue; RT-qPCR was not routinely available for all archived samples, and reported sensitivity should therefore be interpreted as a conservative lower-bound estimate; Phase 2 evaluated analytical sensitivity across all eight panel targets using characterized arboviral reference strains in serial dilution experiments, with reference RT-qPCR assays as the comparator; this phase was incorporated to characterize detection thresholds for targets not represented by clinical specimens. Results: In Phase 1, the M10 demonstrated sensitivity of 96.0% (96/100), specificity of 100% (63/63), overall accuracy of 97.5%, and near-perfect agreement with the reference standard (Cohen’s κ = 0.95). DENV-3 was the predominant serotype (74/96; 77.1%), followed by DENV-1 (16.7%) and DENV-4 (6.3%); DENV-2 was not detected. In Phase 2, operational LoDs (defined as the lowest concentration yielding a detectable Ct in all triplicate reactions for the RT-qPCR, and from a single cartridge per dilution point for the STANDARD M10) were equivalent or superior to reference RT-qPCR for six targets (DENV-1, DENV-3, DENV-4, ZIKV, WNV, YFV; range 1–5 PFU/mL), while DENV-2 and CHIKV showed 20-fold higher operational LoDs (20 PFU/mL vs. 1 PFU/mL for the reference RT-qPCR); formal LoD₉₅ estimates were not determined. Conclusions: The STANDARD M10 Arbovirus Panel shows high clinical accuracy for dengue and adequate analytical sensitivity for most targets, supporting its use as a complementary decentralized molecular tool. Reduced sensitivity for DENV-2 and CHIKV and the absence of formal LoD₉₅ estimates remain key limitations to be addressed in future validation studies. Full article

Background/Objectives: Vector-borne diseases (VBDs) remain a major global public health challenge, particularly in tropical and subtropical regions. In eastern Colombia, the department of Meta reports a high incidence of arboviral infections such as dengue, as well as parasitic diseases including malaria and leishmaniasis. This study aimed to conduct baseline entomological surveillance and molecular screening of Diptera vectors to detect the circulation of arboviruses and parasitic pathogens in two municipalities of Meta, Fuente de Oro and Vista Hermosa. Methods: Adult mosquitoes and sand flies were collected in both municipalities and identified primarily at the genus level, with Anopheles specimens identified to species level. A total of 790 insects were collected, of which 780 were processed in 148 pools and 10 were analyzed individually. Molecular detection of pathogens was performed using PCR and RT-PCR to screen for dengue virus (DENV) serotypes, Zika virus (ZIKV), Chikungunya virus (CHIKV), Oropouche virus (OROV), Plasmodium spp., and Leishmania spp. Results: DENV was detected in 34.8% (55/158) of the processed pools, with DENV-1 identified as the most prevalent serotype. Culex was the most abundant genus overall, particularly in Fuente de Oro, while Aedes predominated in Vista Hermosa. MIR estimates indicated higher molecular detection likelihood in Aedes compared with Culex. Plasmodium vivax and P. falciparum were detected in pools of Anopheles darlingi and Anopheles rangeli, respectively. No molecular evidence of Leishmania DNA was detected in Lutzomyia specimens, and no positive detections were observed for ZIKV, CHIKV, or OROV. Conclusions: The molecular detection of DENV and Plasmodium spp. in field-collected vectors provides valuable baseline evidence of pathogen circulation in Meta, Colombia. While the findings do not imply vector competence, they highlight the importance of sustained entomological surveillance to inform integrated vector control strategies and guide future studies incorporating species-level identification and longitudinal sampling in endemic regions. Full article

In this study, a fractional-order epidemic compartmental model is formulated using the Caputo derivative to account for the memory effects of the chikungunya virus. Based on Banach contractions, fixed-point theorems are used to prove existence and uniqueness, and fundamental properties such as positivity and boundedness are established. Normalized forward sensitivity indices are employed to evaluate the relative impact of model parameters on the transmission dynamics and control of the disease. To reduce the spreading of infection, an optimal control problem is formulated by introducing time-dependent control measures with four control strategies that include public health prevention, treatment enhancement, and vector-control measures. Necessary conditions for optimality are derived using Pontryagin’s Maximum Principle. The predictor–corrector Adams–Bashforth–Moulton scheme is applied across different fractional orders and effectively reduces infection levels. The influence of the fractional order $\xi$ on the epidemic dynamics is investigated, showing that lower values of $\xi$ slow disease progression through a memory effect inherent in the Caputo operator. Moreover, an artificial neural network (ANN) trained via the Levenberg–Marquardt algorithm independently validates the numerical solutions. Full article