Global expansion of chikungunya virus: mapping the 64-year history

A brief overview of chikungunya-related pain

Pain is an important symptom associated with the arboviral disease caused by the Chikungunya virus (CHIKV). For a significant number of patients, this symptom can persist for months or even years, negatively affecting their quality of life. Unfortunately, pharmacological options for this condition are limited and only partially effective, as the underlying mechanisms associated with CHIKV-induced pain are still poorly understood. The re-emergence of CHIKV has led to new outbreaks, and the expected high prevalence of pain in these global events requires new scientific advances to find more effective solutions. Here we review the main aspects of pain caused by CHIKV infection, such as the anatomy of the affected sites, the prevalence and management of this symptom, the diversity of possible cellular and molecular mechanisms, and finally highlight a promising meningeal pathway to elucidate the mechanisms involved in the unsolved problem of CHIKV-associated pain.

Exploration of potential inhibitors against chikungunya envelope: an in-silico clue

Chikungunya virus (CHIKV) is a mosquito-borne virus which causes chikungunya disease. Two biological vectors Aedes aegypti and Aedes albopictus transmit CHIKV to the victim body. According to the report of the European Centre for Disease Prevention and Control, epidemics of chikungunya disease existed in 2024 over America, Africa, Europe and Asia. Although 50% CHIKV infected person show chronic clinical symptoms and several troubles associated with chikungunya, still there are no effective vaccines or medications on market. So availability of another CHIKV inhibiting materials and mechanisms are necessary. For this purpose recently plant-derived bioactive compounds with antiviral properties are used to inhibit chikungunya infection. In this present research work 69 CHIKV inhibiting active compounds were chosen for ADMET analysis. Drug likeness of active compounds was also analyzed based on Lipinski's rule of five. Based on the drug likeness, active compounds (Baicalein, Epicatechin, Genistein, Quercetin, Resveratrol) were finally screened for molecular docking with CHIKV envelope proteins using Auto Dock program. Among the five active compounds, Genistein showed highest binding energy for both E1 (ΔG = - 8.3 kcal/mol) and E2 (ΔG = - 7.1 kcal/mol). Molecular dynamics simulations signify that Genistein forms a stable complex with the CHIKV E1 and E2 proteins over a 50 ns period with a significant number of hydrogen bonds. So this present study concluded that Genistein will act as potent CHIKV E1 and E2 inhibiting active compounds. To evaluate efficiency or inhibiting capacity of finally selected Genistein against CHIKV, in vivo and in vitro validation should be conducted.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40203-025-00351-3.

Genetic diversity of Aedes aegypti populations from Kisumu and Busia counties, western Kenya, and their vector competence for chikungunya virus

Aedes aegypti (Ae. aegypti) is the primary vector of several arboviruses, including dengue virus (DENV), chikungunya virus (CHIKV), yellow fever virus (YFV), and Zika virus (ZIKV). This vector is widespread globally in tropical and subtropical areas but also found in temperate areas. Kenya experienced its first chikungunya outbreak in Lamu County in 2004, followed by subsequent outbreaks in Mandera in 2016 and Mombasa in 2017. Despite the presence of Ae. aegypti in Kisumu and Busia counties, no outbreaks of chikungunya fever have been reported in these two western Kenya counties. To investigate this phenomenon, we collected Ae. aegypti mosquitoes from the county headquarter towns of Kisumu and Busia. The mosquitoes were reared under controlled laboratory conditions, and their genetic diversity assessed using COI gene sequences. Additionally, neutrality tests, including Tajima's D and Fu's FS, were subsequently performed to infer evolutionary dynamics. The mosquitoes were then evaluated for their ability to transmit CHIKV by challenging laboratory-reared F1 generations of field-collected mosquitoes with an infectious blood meal containing CHIKV. Genetic analysis revealed the presence of both Ae. aegypti subspecies, (Ae. aegypti aegypti [Aaa] and Ae. aegypti formosus [Aaf]) in the two western Kenya counties, with Aaf being dominant (19:8 for Kisumu samples and 25:6 for Busia samples). The populations exhibited high haplotype diversity (0.96011 in Kisumu and 0.93763 in Busia) and low nucleotide diversity (0.00913 in Kisumu and 0.00757 in Busia), indicating significant genetic polymorphism at the loci examined. Additionally, negative neutrality tests, including Tajima's D (-1.87530 for Kisumu and -1.09547 for Busia) and Fu's FS (-10.223 for Kisumu and -15.249 for Busia), coupled with a smooth mismatch distribution, suggest that recent evolutionary events may have significantly shaped the genetic structure of these populations. The assessment of vector competence of Ae. aegypti populations from Kisumu and Busia counties revealed their capacity to support CHIKV transmission. Specifically, we demonstrated infection, dissemination, and transmission rates of 55.2%, 85.5%, and 27.1% for Kisumu, and 57.8%, 71.8%, and 25% for Busia, respectively. However, statistical analysis indicated no significant difference in vector competence between the two populations. These findings underscore the uniform potential of Ae. aegypti mosquitoes from both Kisumu and Busia to facilitate the spread of CHIKV, highlighting the need for consistent surveillance and vector management strategies across these regions.

Seroprevalence and risk factors of Chikungunya in Ethiopia: a systematic review and meta-analysis

Introduction

The resurgence of the Chikungunya virus has led to public health concerns due to frequent epidemics worldwide. Chikungunya was first detected in Ethiopia in 2016, and it has been identified in various regions. However, the current status of the disease in Ethiopia remains unknown, underscoring the need for updated information.

Objective

To provide up-to-date epidemiological data on the status of Chikungunya in Ethiopia.

Methods

A systematic review and meta-analysis were conducted using the PubMed, Scopus, and Google Scholar databases in accordance with the PRISMA guidelines, the literature search was conducted from September to October 2024. The search terms used included 'Chikungunya,' 'Chikungunya Virus,' 'Prevalence,' 'Seroprevalence,' 'Risk Factor,' and 'Ethiopia.' The inclusion criteria covered online articles published between 2016 and 2024 in English and published in Ethiopia. The quality assessment involved independent expert evaluations, and publication bias was assessed using Begg's and Egger's tests. The analysis was performed using STATA 17 software.

Results

A total of five articles met the eligibility criteria and were included in the data extraction. The pooled seroprevalence of Chikungunya in Ethiopia was 24.0%. The highest seroprevalence was reported in the Southern Nations, Nationalities, and Peoples' Region (SNNPR), at 43.6%, while the lowest seroprevalence was in Dire Dawa, at approximately 12.0%. Factors such as occupation, education, age, and sex contributed to the variation in seroprevalence of the disease. Subgroup meta-analysis revealed heterogeneity across the types of studies included. No indications of publication bias or small-study effects were found according to Begg's test or Egger's test.

Conclusion and relevance

The pooled prevalence of Chikungunya underscores its significance in Ethiopia, necessitating proactive monitoring, active viral disease surveillance, and robust health system enforcement.

Chikungunya Fever and Rheumatoid Arthritis: A Systematic Review and Meta-Analysis

Chikungunya fever (CHIKF) is a re-emerging infectious disease caused by the chikungunya virus (CHIKV), transmitted primarily by Aedes mosquitoes. A significant number progress to chronic chikungunya arthritis, which shares similarities with rheumatoid arthritis (RA). Despite evidence of a link between CHIKV infection and subsequent RA development, a comprehensive analysis of the relationship between these two diseases is lacking. This study systematically analyzes the incidence of RA after CHIKV infection and its immunological mechanisms, following PRISMA guidelines with literature searches across multiple databases up to 3 September 2024. Eligible studies included retrospective and prospective designs reporting RA diagnoses after CHIKV infection. Data extraction was performed independently, and the risk of bias was assessed using appropriate tools. Sixteen studies involving 2879 patients were included, with 449 individuals diagnosed with RA following CHIKV infection, resulting in a combined incidence of 13.7% (95% CI: 6.12% to 27.87%). High heterogeneity between studies was observed (I2 = 96%), indicating variability related to diagnostic criteria and population characteristics. This review highlights the significant RA incidence after CHIKV infection, emphasizing the need for research on autoimmune mechanisms, long-term rheumatological follow-up, early diagnostic biomarkers, and CHIKV's long-term health impacts.

Excellent capability for molecular detection of Aedes-borne dengue, Zika, and chikungunya viruses but with a need for increased capacity for yellow fever and Japanese encephalitis viruses: an external quality assessment in 36 European laboratories

Mosquito-borne viruses represent a large global health burden. With geographic expansion of competent vectors for chikungunya virus (CHIKV), dengue virus (DENV), and Zika virus (ZIKV) in Europe, it is anticipated that the number of autochthonous cases of these tropical viruses in Europe will increase. Therefore, regular assessment of diagnostic capabilities in Europe is important. Our aim was to evaluate the mosquito-borne virus molecular detection capability of expert European laboratories by conducting an external quality assessment in October 2023. Molecular panels included 12 plasma samples: one alphavirus (CHIKV), four orthoflaviviruses (ZIKV, yellow fever virus [YFV], DENV, and Japanese encephalitis virus [JEV]), and two negative control samples. Mosquito-borne virus detection was assessed among 36 laboratories in 24 European countries. Adequate capabilities were lacking for YFV and JEV. Many laboratories relied on a mix of laboratory-developed tests (some of which were pan-orthoflavivirus or pan-alphavirus in combination with sequencing) and commercial assays. 47.2% of laboratories characterized all external quality assessment (EQA) samples correctly. Correct result rates were 100% for CHIKV and ZIKV and >99% for DENV, but laboratories lacked capacity, specificity, and sensitivity for JEV and YFV. Three of the viruses in this panel emerged and transiently circulated in Europe: CHIKV, ZIKV, and DENV. Molecular detection was excellent for those viruses, but <50% is accurate for the remainder of the panel. With the possibility or continuation of imported cases and a growing global concern about climate change and vector expansion, progress toward rapid, accurate mosquito-borne virus diagnostics in Europe is recommended, as well as regular EQAs to monitor it.IMPORTANCEThe external quality assessment (EQA) focused on Aedes-borne viruses: chikungunya virus (CHIKV), dengue virus (DENV), Zika virus (ZIKV), and yellow fever virus (YFV). Japanese encephalitis virus, an orthoflavivirus that is spread by mosquito species belonging to the genus Culex, was included in the quality assessment as well. CHIKV, DENV, and ZIKV have proven potential for transient and limited circulation in Europe upon introduction of viremic travelers returning to Aedes albopictus-endemic regions. Results of this EQA were excellent for those viruses, but <50% is accurate for the remainder of the panel (YFV and Japanese encephalitis virus). Considering imported cases and the threat of climate change and competent vector expansion, progress toward rapid, accurate mosquito-borne virus diagnostics in Europe is recommended.

The Chikungunya Virus nsP3 Macro Domain Inhibits Activation of the NF-κB Pathway

The role of the chikungunya virus (CHIKV) non-structural protein 3 (nsP3) in the virus lifecycle is poorly understood. The protein comprises three domains. At the N-terminus is a macro domain, biochemically characterised to bind both RNA and ADP-ribose and to possess ADP-ribosyl hydrolase activity-an enzymatic activity that removes ADP-ribose from mono-ADP-ribosylated proteins. As ADP-ribosylation is important in the signalling pathway, leading to activation of the transcription factor NF-κB, we sought to determine whether the macro domain might perturb NF-κB signalling. We first showed that CHIKV infection did not induce NF-κB activation and could not block exogenous activation of the pathway via TNFα, although TNFα treatment did result in a modest reduction in virus titre. In contrast, ectopic expression of nsP3 was able to inhibit both basal and TNFα-mediated NF-κB activation, and this was dependent on the macro domain, as a mutation previously shown to disrupt ADP-ribose binding and hydrolase activity (D10A) eliminated the ability to inhibit NF-κB activation. The macro domain D10A mutant also resulted in a dramatic reduction in virus infectivity, consistent with the notion that the ability of the macro domain to inhibit NF-κB activation plays a role in the virus lifecycle.

Visualizing the virus world inside the cell by cryo-electron tomography

Structural studies on purified virus have revealed intricate architectures, but there is little structural information on how viruses interact with host cells in situ. Cryo-focused ion beam (FIB) milling and cryo-electron tomography (cryo-ET) have emerged as revolutionary tools in structural biology to visualize the dynamic conformational of viral particles and their interactions with host factors within infected cells. Here, we review the state-of-the-art cryo-ET technique for in situ viral structure studies and highlight exemplary studies that showcase the remarkable capabilities of cryo-ET in capturing the dynamic virus-host interaction, advancing our understanding of viral infection and pathogenesis.

Spatial-temporal distribution of chikungunya virus in Brazil: a review on the circulating viral genotypes and Aedes (Stegomyia) albopictus as a potential vector

Chikungunya virus (CHIKV) is mainly transmitted by the invasive mosquito Aedes (Stegomyia) aegypti in tropical and subtropical regions worldwide. However, genetic adaptations of the virus to the peri domestic mosquito vector Aedes (Stegomyia) albopictus has resulted in enhanced vector competence and associated epidemics and may contribute to further geographic expansion of CHIKV. However, evidence-based data on the relative role of Ae. albopictus in CHIKV transmission dynamics are scarce, especially in regions where Ae. aegypti is the main vector, such as in Brazil. Here, we review the CHIKV genotypes circulating in Brazil, spatial and temporal distribution of Chikungunya cases in Brazil, and susceptibility to infection and transmission (i.e., vector competence) of Ae. albopictus for CHIKV to better understand its relative contribution to the virus transmission dynamics.

RT-RPA as a dual tool for detection and phylogenetic analysis of epidemic arthritogenic alphaviruses

Chikungunya (CHIKV), o'nyong-nyong (ONNV), and Mayaro (MAYV) viruses are transmitted by mosquitoes and known to cause a debilitating arthritogenic syndrome. These alphaviruses have emerged and re-emerged, leading to outbreaks in tropical and subtropical regions of Asia, South America, and Africa. Despite their prevalence, there persists a critical gap in the availability of sensitive and virus-specific point-of-care (POC) diagnostics. Traditional immunoglobulin-based tests such as enzyme-linked immunosorbent assay (ELISA) often yield cross-reactive results due to the close genetic relationship between these viruses. Molecular diagnostics such as quantitative polymerase chain reaction (qPCR) offer high sensitivity but are limited by the need for specialized laboratory equipment. Recombinase polymerase amplification (RPA), an isothermal amplification method, is a promising alternative to qPCR, providing rapid results with minimal equipment requirements. Here, we report the development and validation of three virus-specific RT-RPA-based rapid tests for CHIKV, ONNV, and MAYV. These tests demonstrated both speed and sensitivity, capable of detecting 10-100 viral copies within 20 min of amplification, without exhibiting cross-reactivity. Furthermore, we evaluated the clinical potential of these tests using serum and tissue samples from CHIKV, ONNV, and MAYV-infected mice, as well as CHIKV-infected human patients. We demonstrate that the RPA amplicons derived from the patient samples can be sequenced, enabling cost-effective molecular epidemiological studies. Our findings highlight the significance of these rapid and specific diagnostics in improving the early detection and management of these arboviral infections, particularly in resource-limited settings.

Nonhuman primate models of pediatric viral diseases

Infectious diseases are the leading cause of death in infants and children under 5 years of age. In utero exposure to viruses can lead to spontaneous abortion, preterm birth, congenital abnormalities or other developmental defects, often resulting in lifelong health sequalae. The underlying biological mechanisms are difficult to study in humans due to ethical concerns and limited sample access. Nonhuman primates (NHP) are closely related to humans, and pregnancy and immune ontogeny in infants are very similar to humans. Therefore, NHP are a highly relevant model for understanding fetal and postnatal virus-host interactions and to define immune mechanisms associated with increased morbidity and mortality in infants. We will discuss NHP models of viruses causing congenital infections, respiratory diseases in early life, and HIV. Cytomegalovirus (CMV) remains the most common cause of congenital defects worldwide. Measles is a vaccine-preventable disease, yet measles cases are resurging. Zika is an example of an emerging arbovirus with devastating consequences for the developing fetus and the surviving infant. Among the respiratory viruses, we will discuss influenza and Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). We will finish with HIV as an example of a lifelong infection without a cure or vaccine. The review will highlight (i) the impact of viral infections on fetal and infant immune development, (ii) how differences in infant and adult immune responses to infection alter disease outcome, and emphasize the invaluable contribution of pediatric NHP infection models to the design of effective treatment and prevention strategies, including vaccines, for human infants.

Results of a Nationally Representative Seroprevalence Survey of Chikungunya Virus in Bangladesh

There is an increasing global burden from chikungunya virus (CHIKV). Bangladesh reported a major epidemic in 2017, but it was unclear whether there had been prior widespread transmission. We conducted a nationally representative seroprevalence survey in 70 randomly selected communities immediately before the epidemic. We found that 69 of 2938 sampled individuals (2.4%) were seropositive to CHIKV. Seropositivity to dengue virus (adjusted odds ratio, 3.13 [95% confidence interval, 1.86-5.27]), male sex (0.59 [.36-.99]), and community presence of Aedes aegypti mosquitoes (1.80 [1.05-3.0]7) were significantly associated with CHIKV seropositivity. Using a spatial prediction model, we estimated that across the country, 4.99 (95% confidence interval, 4.89-5.08) million people had been previously infected. These findings highlight high population susceptibility before the major outbreak and that previous outbreaks must have been spatially isolated.

Detection of dengue virus and chikungunya virus in wastewater in Portugal: an exploratory surveillance study

BACKGROUND

The global distribution and prevalence of arboviral diseases have increased in recent years, driven by factors such as climate change, biodiversity loss, globalisation, and urbanisation. These diseases are often underestimated due to uneven surveillance and unreported asymptomatic cases. Current surveillance relies on vector and clinical surveillance. In this study, we aimed to explore wastewater-based surveillance (WBS) as an additional tool for dengue virus (DENV) and chikungunya virus (CHIKV) tracking.

METHODS

In this exploratory surveillance study, WBS was done at eleven wastewater treatment plants in three regions in Portugal (North, Lisboa and Vale do Tejo, and south). Using quantitative RT-PCR, we quantified in raw wastewater the RNA concentrations of DENV and CHIKV (non-structural viral protein 1 [nsP1] and envelope protein [E1] genes) once every 2 weeks for a period of 11 months, between May 16, 2022, and April 19, 2023. Results were normalised with crAssphage (concentration of target viral RNA divided by the concentration of crAssphage DNA) and provided as median normalised viral load. Prevalence (proportion of positive samples) and viral quantities were summarised for the total sampling period, by calendar month, and by seasons.

FINDINGS

273 samples were collected from 11 wastewater treatment plants situated across the North (n=75 samples), Lisboa and Vale do Tejo (n=98), and south (n=100) regions of Portugal. DENV was detected in 68 (25%) of 273 samples, with a median viral load of 1·1 × 10-4 (IQR 3·2 × 10-5 to 8·0 × 10-4). CHIKV was detected in 30 (11%) of 273 samples, with median viral loads of 3·1 × 10-4 (1·6 × 10-4 to 6·4 × 10-4; nsP1 gene) and 7·8 × 10-4 (4·2 × 10-4 to 2·0 × 10-³; E1 gene). The pattern of occurrence of CHIKV was similar between regions whereas slight differences were found for DENV. When combining results for the three studied regions, DENV prevalence and viral load had two seasonal peaks (summer and winter) and CHIKV prevalence and viral load had a single peak during March and April of 2023.

INTERPRETATION

This study highlights the potential of WBS as a potent tool for gauging the epidemiological landscape of DENV and CHIKV in Portugal, where autochthonous cases have not yet been detected. WBS could serve as an additional element to conventional surveillance approaches, especially in areas where real-time clinical surveillance data are scarce or delayed.

FUNDING

EU Emergency Support Instrument and Fundação para a Ciencia e Tecnologia.

From bench to clinic: the development of VLA1553/IXCHIQ, a live-attenuated chikungunya vaccine

BACKGROUND

Over the past 20 years, over 5 million cases of chikungunya, a mosquito-transmitted viral disease, have been reported in over 110 countries. Until recently, preventative strategies for chikungunya were largely ineffective, relying on vector control and individual avoidance of mosquito bites.

METHODS

This review outlines the preclinical and clinical efficacy and safety data that led to the approval of VLA1553 (IXCHIQ®), a live-attenuated vaccine against chikungunya disease. It also describes the innovative development pathway of VLA1553, based on an immunological surrogate of protection, and discusses ongoing and future post-licensure studies.

RESULTS

In mice and non-human primate models, VLA1553 elicited high titres of neutralizing antibodies, conferred protection against wild-type chikungunya virus challenge and raised no safety concerns. A Phase 1 clinical trial of VLA1553 demonstrated 100% seroconversion among 120 healthy participants, with sustained neutralizing antibody titres after 12 months. These results and determination of a surrogate marker of protection led to advancement of VLA1553 directly into Phase 3 clinical development, as agreed with the US Food and Drug Administration (FDA) and the European Medicines Agency. The pivotal Phase 3 trial met its primary immunogenicity endpoint, achieving seroprotective levels based on immuno-bridging in baseline seronegative participants 28 days post-vaccination. These findings enabled submission of a Biologics Licence Application to the FDA for accelerated approval of VLA1553 in the US for adults aged ≥18 years. Ongoing and planned studies will confirm the clinical efficacy/effectiveness and safety of VLA1553 in adults and younger individuals, and will generate data in chikungunya endemic countries that have the highest unmet need.

CONCLUSION

VLA1553 is the first vaccine approved for the prevention of chikungunya disease in adults, following accelerated development based on a serological surrogate marker of protection. VLA1553 adds to strategies to reduce the spread and burden of chikungunya in endemic populations and travellers.

Immunogenicity and Safety of Chikungunya Vaccines: A Systematic Review and Meta-Analysis

Several vaccines against chikungunya fever have been developed and tested, and one has been recently licensed. We performed a meta-analysis to estimate the immunogenicity and safety of all chikungunya vaccines that have been progressed to clinical trial evaluation (VLA1553; mRNA-1388/VAL-181388; PXVX0317/VRC-CHKVLP059-00-VP; ChAdOx1 Chik; MV-CHIK). We included trials retrieved from MedLine, Scopus, and ClinicalTrials.gov. The outcomes were the rates of seroconversion/seroresponse and serious adverse events (SAEs) after the primary immunization course. We retrieved a total of 14 datasets, including >4000 participants. All candidate chikungunya vaccines were able to elicit an immunogenic response in ≥96% of vaccinated subjects, regardless of the vaccination schedule and platform used, and the seroconversion/seroresponse rates remained high 6 to 12 months after vaccination for most vaccines. Four of the five candidate vaccines showed a good overall safety profile (no data were available for ChAdOx1 Chik), with no significant increase in the risk of SAEs among the vaccinated, and a low absolute risk of product-related SAEs. Overall, the present findings support the potential use of the candidate vaccines for the prevention of chikungunya and the current indication for use in adult travelers to endemic regions of the licensed VLA 1553 vaccine. In order to extend chikungunya vaccination to a wider audience, further studies are needed on individuals from endemic countries and frail populations.

In situ fate of Chikungunya virus replication organelles

Chikungunya virus (CHIKV) is a mosquito-borne pathogen responsible for an acute musculoskeletal disease in humans. Replication of the viral RNA genome occurs in specialized membranous replication organelles (ROs) or spherules, which contain the viral replication complex. Initially generated by RNA synthesis-associated plasma membrane deformation, alphavirus ROs are generally rapidly endocytosed to produce type I cytopathic vacuoles (CPV-I), from which nascent RNAs are extruded for cytoplasmic translation. By contrast, CHIKV ROs are poorly internalized, raising the question of their fate and functionality at the late stage of infection. Here, using in situ cryogenic-electron microscopy approaches, we investigate the outcome of CHIKV ROs and associated replication machinery in infected human cells. We evidence the late persistence of CHIKV ROs at the plasma membrane with a crowned protein complex at the spherule neck similar to the recently resolved replication complex. The unexpectedly heterogeneous and large diameter of these compartments suggests a continuous, dynamic growth of these organelles beyond the replication of a single RNA genome. Ultrastructural analysis of surrounding cytoplasmic regions supports that outgrown CHIKV ROs remain dynamically active in viral RNA synthesis and export to the cell cytosol for protein translation. Interestingly, rare ROs with a homogeneous diameter are also marginally internalized in CPV-I near honeycomb-like arrangements of unknown function, which are absent in uninfected controls, thereby suggesting a temporal regulation of this internalization. Altogether, this study sheds new light on the dynamic pattern of CHIKV ROs and associated viral replication at the interface with cell membranes in infected cells.IMPORTANCEThe Chikungunya virus (CHIKV) is a positive-stranded RNA virus that requires specialized membranous replication organelles (ROs) for its genome replication. Our knowledge of this viral cycle stage is still incomplete, notably regarding the fate and functional dynamics of CHIKV ROs in infected cells. Here, we show that CHIKV ROs are maintained at the plasma membrane beyond the first viral cycle, continuing to grow and be dynamically active both in viral RNA replication and in its export to the cell cytosol, where translation occurs in proximity to ROs. This contrasts with the homogeneous diameter of ROs during internalization in cytoplasmic vacuoles, which are often associated with honeycomb-like arrangements of unknown function, suggesting a regulated mechanism. This study sheds new light on the dynamics and fate of CHIKV ROs in human cells and, consequently, on our understanding of the Chikungunya viral cycle.

Understanding the Transmission Dynamics of the Chikungunya Virus in Africa

The Chikungunya virus (CHIKV) poses a significant global public health concern, especially in Africa. Since its first isolation in Tanzania in 1953, CHIKV has caused recurrent outbreaks, challenging healthcare systems in low-resource settings. Recent outbreaks in Africa highlight the dynamic nature of CHIKV transmission and the challenges of underreporting and underdiagnosis. Here, we review the literature and analyse publicly available cases, outbreaks, and genomic data, providing insights into the epidemiology, genetic diversity, and transmission dynamics of CHIKV in Africa. Our analyses reveal the circulation of geographically distinct CHIKV genotypes, with certain regions experiencing a disproportionate burden of disease. Phylogenetic analysis of sporadic outbreaks in West Africa suggests repeated emergence of the virus through enzootic spillover, which is markedly different from inferred transmission dynamics in East Africa, where the virus is often introduced from Asian outbreaks, including the recent reintroduction of the Indian Ocean lineage from the Indian subcontinent to East Africa. Furthermore, there is limited evidence of viral movement between these two regions. Understanding the history and transmission dynamics of outbreaks is crucial for effective public health planning. Despite advances in surveillance and research, diagnostic and surveillance challenges persist. This review and secondary analysis highlight the importance of ongoing surveillance, research, and collaboration to mitigate the burden of CHIKV in Africa and improve public health outcomes.

The evolutionary and molecular history of a chikungunya virus outbreak lineage

In 2018-2019, Thailand experienced a nationwide spread of chikungunya virus (CHIKV), with approximately 15,000 confirmed cases of disease reported. Here, we investigated the evolutionary and molecular history of the East/Central/South African (ECSA) genotype to determine the origins of the 2018-2019 CHIKV outbreak in Thailand. This was done using newly sequenced clinical samples from travellers returning to Sweden from Thailand in late 2018 and early 2019 and previously published genome sequences. Our phylogeographic analysis showed that before the outbreak in Thailand, the Indian Ocean lineage (IOL) found within the ESCA, had evolved and circulated in East Africa, South Asia, and Southeast Asia for about 15 years. In the first half of 2017, an introduction occurred into Thailand from another South Asian country, most likely Bangladesh, which subsequently developed into a large outbreak in Thailand with export to neighbouring countries. Based on comparative phylogenetic analyses of the complete CHIKV genome and protein modelling, we identified several mutations in the E1/E2 spike complex, such as E1 K211E and E2 V264A, which are highly relevant as they may lead to changes in vector competence, transmission efficiency and pathogenicity of the virus. A number of mutations (E2 G205S, Nsp3 D372E, Nsp2 V793A), that emerged shortly before the outbreak of the virus in Thailand in 2018 may have altered antibody binding and recognition due to their position. This study not only improves our understanding of the factors contributing to the epidemic in Southeast Asia, but also has implications for the development of effective response strategies and the potential development of new vaccines.

The Stop Codon after the nsp3 Gene of Ross River Virus (RRV) Is Not Essential for Virus Replication in Three Cell Lines Tested, but RRV Replication Is Attenuated in HEK 293T Cells

A recombinant Ross River virus (RRV) that contains the fluorescent protein mCherry fused to the non-structural protein 3 (nsP3) was constructed, which allowed real-time imaging of viral replication. RRV-mCherry contained either the natural opal stop codon after the nsP3 gene or was constructed without a stop codon. The mCherry fusion protein did not interfere with the viral life cycle and deletion of the stop codon did not change the replication capacity of RRV-mCherry. Comparison of RRV-mCherry and chikungunya virus-mCherry infections, however, showed a cell type-dependent delay in RRV-mCherry replication in HEK 293T cells. This delay was not caused by differences in cell entry, but rather by an impeded nsP expression caused by the RRV inhibitor ZAP (zinc finger CCCH-Type, antiviral 1). The data indicate that viral replication of alphaviruses is cell-type dependent, and might be unique for each alphavirus.

Detection of two alphaviruses: Middelburg virus and Sindbis virus from enzootic amplification cycles in southwestern Uganda

Our knowledge of alphavirus genetic diversity is mainly based on viruses isolated from anthropophilic mosquito species, humans, and livestock during outbreaks. Studies on alphaviruses from sylvatic amplification cycles in sub-Saharan Africa have been conducted less often than from epizootic environments. To gain insight into alphavirus diversity in enzootic transmission cycles, we collected over 23,000 mosquitoes in lowland rainforest and savannah gallery forest in southwestern Uganda and tested them for alphavirus infections. We detected Sindbis virus (SINV) in a Culex Culex sp. mosquito and Middelburg virus (MIDV) in Eretmapodites intermedius and Mansonia africana. MIDV is a mosquito-borne alphavirus that causes febrile illness in sheep, goats, and horses and was previously not known to occur in Uganda. SINV, also a mosquito-borne alphavirus, causes mild infections in humans. Full genomes of SINV and MIDV were sequenced, showing a nucleotide identity of 99% to related strains. Both isolates replicated to high titres in a wide variety of vertebrate cells. Our data suggest endemic circulation of SINV and MIDV in Uganda.

Modeling the Regional Distribution of International Travelers in Spain to Estimate Imported Cases of Dengue and Malaria: Statistical Inference and Validation Study

BACKGROUND

Understanding the patterns of disease importation through international travel is paramount for effective public health interventions and global disease surveillance. While global airline network data have been used to assist in outbreak prevention and effective preparedness, accurately estimating how these imported cases disseminate locally in receiving countries remains a challenge.

OBJECTIVE

This study aimed to describe and understand the regional distribution of imported cases of dengue and malaria upon arrival in Spain via air travel.

METHODS

We have proposed a method to describe the regional distribution of imported cases of dengue and malaria based on the computation of the "travelers' index" from readily available socioeconomic data. We combined indicators representing the main drivers for international travel, including tourism, economy, and visits to friends and relatives, to measure the relative appeal of each region in the importing country for travelers. We validated the resulting estimates by comparing them with the reported cases of malaria and dengue in Spain from 2015 to 2019. We also assessed which motivation provided more accurate estimates for imported cases of both diseases.

RESULTS

The estimates provided by the best fitted model showed high correlation with notified cases of malaria (0.94) and dengue (0.87), with economic motivation being the most relevant for imported cases of malaria and visits to friends and relatives being the most relevant for imported cases of dengue.

CONCLUSIONS

Factual descriptions of the local movement of international travelers may substantially enhance the design of cost-effective prevention policies and control strategies, and essentially contribute to decision-support systems. Our approach contributes in this direction by providing a reliable estimate of the number of imported cases of nonendemic diseases, which could be generalized to other applications. Realistic risk assessments will be obtained by combining this regional predictor with the observed local distribution of vectors.

Development of RT-RPA-based point-of-care tests for epidemic arthritogenic alphaviruses

Chikungunya (CHIKV), o'nyong-nyong (ONNV), and Mayaro (MAYV) viruses are transmitted by mosquitoes and known to cause a debilitating arthritogenic syndrome. These alphaviruses have emerged and re-emerged, leading to outbreaks in tropical and subtropical regions of Asia, South America, and Africa. Despite their prevalence, there persists a critical gap in the availability of sensitive and virus-specific point-of-care (POC) diagnostics. Traditional immunoglobulin-based tests such as enzyme-linked immunosorbent assay (ELISAs) often yield cross-reactive results due to the close genetic relationship between these viruses. Molecular diagnostics such as quantitative polymerase chain reaction (qPCR) offer high sensitivity but are limited by the need for specialized laboratory equipment. Recombinase polymerase amplification (RPA), an isothermal amplification method, is a promising alternative to qPCR, providing rapid results with minimal equipment requirements. Here, we report the development and validation of three virus-specific RPA-based POC tests for CHIKV, ONNV, and MAYV. These tests demonstrated both speed and sensitivity, capable of detecting 10 viral copies within 20 minutes of amplification, without exhibiting cross-reactivity. Furthermore, we evaluated the clinical potential of these tests using serum and tissue samples from CHIKV, ONNV, and MAYV-infected mice, as well as CHIKV-infected human patients. We demonstrate that the RPA amplicons derived from the patient samples can be sequenced, enabling cost-effective molecular epidemiological studies. Our findings highlight the significance of these rapid and specific POC diagnostics in improving the early detection and management of these arboviral infections.

Viremia and clinical manifestations in acute febrile patients of Chikungunya infection during the 2016 CHIKV outbreak in Delhi, India

Background

Chikungunya virus (CHIKV) is an infectious agent that caused several outbreaks among different countries and affected approximately 1.3 million Indian populations. It is transmitted by Aedes mosquito-either A. albopictus or A. aegypti. Generally, the clinical manifestations of CHIKV infection involve high-grade fever, joint pain, skin rashes, headache, and myalgia. The present study aims to investigate the relationship between the CHIKV virus load and clinical symptoms of the CHIKV infection so that better patient management can be done in the background of the CHIKV outbreak as there is no licensed anti-viral drug and approved vaccines available against CHIKV.

Methods

CHIKV RTPCR positive samples (n = 18) (Acute febrile patients having D.O.F ≤ 7 days) were taken for the quantification of CHIKV viremia by Real-Time PCR. Clinical features of the febrile patients were recorded during the collection of blood samples.

Results

The log mean virus load of 18 RT-PCR-positive samples was 1.3 × 106 copies/mL (1.21 × 103-2.33 × 108 copies/mL). Among the observed clinical features, the log mean virus load (CHIKV) of the patients without skin rash is higher than in the patients with skin rash (6.61 vs 5.5, P = 0.0435).

Conclusion

The conclusion of the study was that the patients with skin rashes had lower viral load and those without skin rashes had higher viral load.

Human muscle cells sensitivity to chikungunya virus infection relies on their glycolysis activity and differentiation stage

Changes to our environment have led to the emergence of human pathogens such as chikungunya virus. Chikungunya virus infection is today a major public health concern. It is a debilitating chronic disease impeding patients' mobility, affecting millions of people. Disease development relies on skeletal muscle infection. The importance of skeletal muscle in chikungunya virus infection led to the hypothesis that it could serve as a viral reservoir and could participate to virus persistence. Here we questioned the interconnection between skeletal muscle cells metabolism, their differentiation stage and the infectivity of the chikungunya virus. We infected human skeletal muscle stem cells at different stages of differentiation with chikungunya virus to study the impact of their metabolism on virus production and inversely the impact of virus on cell metabolism. We observed that chikungunya virus infectivity is cell differentiation and metabolism-dependent. Chikungunya virus interferes with the cellular metabolism in quiescent undifferentiated and proliferative muscle cells. Moreover, activation of chikungunya infected quiescent muscle stem cells, induces their proliferation, increases glycolysis and amplifies virus production. Therefore, our results showed that Chikungunya virus infectivity and the antiviral response of skeletal muscle cells relies on their energetic metabolism and their differentiation stage. Then, muscle stem cells could serve as viral reservoir producing virus after their activation.

Quality of Life and Disability in Chikungunya Arthritis

BACKGROUND

Chikungunya virus infection, transmitted by Aedes mosquito vectors, causes outbreaks of chikungunya fever (CHIKF), throughout the tropical and subtropical world. Following acute infection, many CHIKF patients develop a second phase, chronic and disabling arthritis.

OBJECTIVE

To evaluate the impact of chikungunya arthritis (CHIKA) on quality of life and disability in a cohort of Brazilian CHIKA patients.

METHODS

We conducted a descriptive, non-interventionist, retrospective cross-sectional study analysing data collected from the medical records of chikungunya virus-infected patients treated between June 1, 2022, and June 30, 2022, in the Brazilian rheumatology clinic of one of us (JKA). To assess disability, quality of life, and pain, patients were evaluated using the Health Assessment Questionnaire Disability Index (HAQ-DI), 12-Item Short-Form Health Survey (SF-12), and Visual Analog Scale (VAS) pain.

RESULTS

Forty-two women with a mean (± SD) age of 57.83 (± 13.05) years had CHIKF confirmed by chikungunya-specific serology. The mean (± SD) time between the onset of chikungunya symptoms and the first clinic visit was 55.19 (± 25.88) days. At this visit, the mean (± SD) VAS pain score and DAS28-ESR were 77.26 (± 23.71) and 5.8 (± 1.29), respectively. The mean (± SD) HAQDI score was 1.52 (± 0.67). The mean (± SD) SF-12 PCS-12 was 29.57 (± 8.62) and SF-12 MCS-12 was 38.42 (± 9.85).

CONCLUSION

CHIKA is often highly disabling. As the mosquito vectors that transmit this illness have spread to every continent except Antarctica, there is a potential for widespread public health impact from CHIKA and the need for more effective, early intervention to prevent CHIKA.

Chikungunya Arthritis Treatment with Methotrexate and Dexamethasone: A Randomized, Double-blind, Placebo-controlled Trial

BACKGROUND

Chikungunya fever is a reemerging epidemic disease caused by a single-stranded RNA alphavirus transmitted throughout by Aedes mosquitoes. Chikungunya virus infection is a biphasic disease in which 72% to 95% of affected individuals manifest acute chikungunya fever. Following the acute phase, more than 40% of affected individuals develop arthritis, often lasting more than 3 months, referred to as chronic chikungunya arthritis, which frequently mimics rheumatoid arthritis.

OBJECTIVE

This study aimed to evaluate the efficacy and safety of treatment of chronic chikungunya arthritis with methotrexate and dexamethasone in a randomized, double-blind, placebo-controlled clinical trial.

METHODS

The patients were reassessed for treatment response by the DAS28-ESR, tender joint count and swollen joint count, Patient Global Assessment, and for secondary measures, including the Health Assessment Questionnaire Disability Index and Pain Visual Analog Scale.

RESULTS

Thirty-one subjects were randomized (placebo, n = 16; methotrexate, n = 15); 27 completed treatment and 4 discontinued during the 8-week blinded period. Among the participants, 96.8% were female, with mean ± SD age was 52.9 ± 13. The mean ± SD disease duration prior to treatment was 220.9 ± 51.2 days. At 8 weeks, methotrexate-treated subjects showed a greater numerical trend towards improvement, but there were no significant differences between methotrexate- dexamethasone group and dexamethasone (placebo) group.

CONCLUSION

In this relatively small cohort, all of whom received background dexamethasone, there was a greater numerical improvement trend in prespecified outcome measures, but methotrexate in combination with dexamethasone was not superior to dexamethasone in chronic chikungunya arthritis.

An overview of the mosquitoes of Saudi Arabia (Diptera: Culicidae), with updated keys to the adult females

Despite the fact that mosquito-borne infections have considerable consequences for public health in Saudi Arabia, there is neither a thorough review of the species that occur in the country nor updated keys for the identification of the adult females. In this study, species accounts are given for 49 Saudi Arabian mosquito species, as well as Aedes albopictus (Skuse), which is not recorded in Saudi Arabia, but is medically important and is found in some countries of the Middle East and North Africa. Taxonomic notes provide additional information for certain taxa and/or aid their identification.

Model-based estimates of chikungunya epidemiological parameters and outbreak risk from varied data types

Assessing the factors responsible for differences in outbreak severity for the same pathogen is a challenging task, since outbreak data are often incomplete and may vary in type across outbreaks (e.g., daily case counts, serology, cases per household). We propose that outbreaks described with varied data types can be directly compared by using those data to estimate a common set of epidemiological parameters. To demonstrate this for chikungunya virus (CHIKV), we developed a realistic model of CHIKV transmission, along with a Bayesian inference method that accommodates any type of outbreak data that can be simulated. The inference method makes use of the fact that all data types arise from the same transmission process, which is simulated by the model. We applied these tools to data from three real-world outbreaks of CHIKV in Italy, Cambodia, and Bangladesh to estimate nine model parameters. We found that these populations differed in several parameters, including pre-existing immunity and house-to-house differences in mosquito activity. These differences resulted in posterior predictions of local CHIKV transmission risk that varied nearly fourfold: 16% in Italy, 28% in Cambodia, and 62% in Bangladesh. Our inference method and model can be applied to improve understanding of the epidemiology of CHIKV and other pathogens for which outbreaks are described with varied data types.

Chikungunya in Zhejiang Province, Southeast China

Background

Chikungunya is emerging and reemerging word-widely in the past decades. It is non-endemic in Zhejiang Province, Southeast China. Aedes albopictus, one of major vectors of chikungunya, is widely-distribution in Zhejiang, and autochthonous transmission is possible after introducing chikungunya virus.

Methods

Retrospectively collected the epidemiological, clinical and genetic data of chikungunya and conducted the descriptive analysis and gene sequence analysis.

Results

From 2008 to 2022, 29 chikungunya cases, including 26 overseas imported and 3 local cases, were reported and no cases died of chikungunya. More than half of the imported cases (53.85%) were from Southeast Asia. Seasonal peak of the imported cases was noted between August and September, and 42.31% cases onset in those 2 months. Eight prefecture-level cities and 16 counties reported cases during the study period, with Jinghua (27.59%) and Hangzhou (24.14%) reporting the largest number of cases. The 3 local cases were all reported in Qujiang, Quzhou in 2017. For imported cases, the male-female gender ratio was 2.71:1, 20-30 years old cases (46.15%) and commercial service (42.31%) accounted for the highest proportion. Clinically, fever (100%), fatigue (94.44%), arthralgia (79.17%), headache (71.43%) and erythra (65.22%) were the most common reported symptoms. Eight whole-genome sequences were obtained and belonged to East/Central/South African (ECSA) or Asian genotype.

Conclusions

With the change of immigration policy, the surveillance of chikungunya should be strengthened and the ability of the case discovery and diagnosis should be improved in Zhejiang in the post-COVID-19 era.

Genus Culex Linnaeus, 1758 (Diptera: Culicidae) as an Important Potential Arbovirus Vector in Brazil: An Integrative Review

The genus Culex has 817 species subdivided into 28 subgenera. It has a cosmopolitan distribution, being most abundant in countries with a tropical climate. Understanding the ecology and diversity of viruses circulating in the species of this genus is important for understanding their role as arbovirus vectors in Brazil. To conduct an integrative review to identify the importance of the Culex genus as arbovirus vectors in Brazil. A search was carried out for scientific papers in the PubMed, BVSalud, Patuá-IEC and International Catalogue of Arboviruses: including certain other viruses of vertebrates databases. 36 publications describing arbovirus detections in Culex mosquitoes collected in the field in Brazil were evaluated. A total of 42 arbovirus species were detected, as well as studies analyzing the vector competence of C. quinquefasciatus for the transmission of four different arboviruses. The study of the Culex genus and its role as a vector of arboviruses in Brazil is essential for understanding transmission cycles, with the main aim of reducing cases of human infection. Thus, entomovirological surveillance guides the implementation of actions to detect circulating arboviruses among vectors to anticipate measures aimed at preventing or reducing the risk of arbovirus outbreaks in the country.

Mitochondrial protein BNIP3 regulates Chikungunya virus replication in the early stages of infection

Chikungunya virus (CHIKV) is a human pathogen causing outbreaks of febrile illness for which vaccines and specific treatments remain unavailable. Autophagy-related (ATG) proteins and autophagy receptors are a set of host factors that participate in autophagy, but have also shown to function in other unrelated cellular pathways. Although autophagy is reported to both inhibit and enhance CHIKV replication, the specific role of individual ATG proteins remains largely unknown. Here, a siRNA screen was performed to evaluate the importance of the ATG proteome and autophagy receptors in controlling CHIKV infection. We observed that 7 out of 50 ATG proteins impact the replication of CHIKV. Among those, depletion of the mitochondrial protein and autophagy receptor BCL2 Interacting Protein 3 (BNIP3) increased CHIKV infection. Interestingly, BNIP3 controls CHIKV independently of autophagy and cell death. Detailed analysis of the CHIKV viral cycle revealed that BNIP3 interferes with the early stages of infection. Moreover, the antiviral role of BNIP3 was found conserved across two distinct CHIKV genotypes and the closely related Semliki Forest virus. Altogether, this study describes a novel and previously unknown function of the mitochondrial protein BNIP3 in the control of the early stages of the alphavirus viral cycle.

Seroprevalence of Dengue and Chikungunya Virus Infections in Children Living in Sub-Saharan Africa: Systematic Review and Meta-Analysis

Dengue and chikungunya viruses are frequent causes of malarial-like febrile illness in children. The rapid increase in virus transmission by mosquitoes is a global health concern. This is the first systematic review and meta-analysis of the childhood prevalence of dengue and chikungunya in Sub-Saharan Africa (SSA). A comprehensive search of the MEDLINE (Ovid), Embase (Ovid), and Cochrane Library (Wiley) databases was conducted on 28 June 2019, and updated on 12 February 2022. The search strategy was designed to retrieve all articles pertaining to arboviruses in SSA children using both controlled vocabulary and keywords. The pooled (weighted) proportion of dengue and chikungunya was estimated using a random effect model. The overall pooled prevalence of dengue and chikungunya in SSA children was estimated to be 16% and 7%, respectively. Prevalence was slightly lower during the period 2010-2020 compared to 2000-2009. The study design varied depending on the healthcare facility reporting the disease outbreak. Importantly, laboratory methods used to detect arbovirus infections differed. The present review documents the prevalence of dengue and chikungunya in pediatric patients throughout SSA. The results provide unprecedented insight into the transmission of dengue and chikungunya viruses among these children and highlight the need for enhanced surveillance and controlled methodology.

Ecological Niche Modeling of Aedes and Culex Mosquitoes: A Risk Map for Chikungunya and West Nile Viruses in Zambia

The circulation of both West Nile Virus (WNV) and Chikungunya Virus (CHIKV) in humans and animals, coupled with a favorable tropical climate for mosquito proliferation in Zambia, call for the need for a better understanding of the ecological and epidemiological factors that govern their transmission dynamics in this region. This study aimed to examine the contribution of climatic variables to the distribution of Culex and Aedes mosquito species, which are potential vectors of CHIKV, WNV, and other arboviruses of public-health concern. Mosquitoes collected from Lusaka as well as from the Central and Southern provinces of Zambia were sorted by species within the Culex and Aedes genera, both of which have the potential to transmit viruses. The MaxEnt software was utilized to predict areas at risk of WNV and CHIKV based on the occurrence data on mosquitoes and environmental covariates. The model predictions show three distinct spatial hotspots, ranging from the high-probability regions to the medium- and low-probability regions. Regions along Lake Kariba, the Kafue River, and the Luangwa Rivers, as well as along the Mumbwa, Chibombo, Kapiri Mposhi, and Mpika districts were predicted to be suitable habitats for both species. The rainfall and temperature extremes were the most contributing variables in the predictive models.

Chikungunya virus infection in the southernmost state of Brazil was characterised by self-limited transmission (2017-2019) and a larger 2021 outbreak

BACKGROUND

Chikungunya is a mosquito-borne virus that has been causing large outbreaks in the Americas since 2014. In Brazil, Asian-Caribbean (AC) and East-Central-South-African (ECSA) genotypes have been detected and lead to large outbreaks in several Brazilian states. In Rio Grande do Sul (RS), the southernmost state of Brazil, the first cases were reported in 2016.

OBJECTIVES AND METHODS

We employed genome sequencing and epidemiological investigation to characterise the Chikungunya fever (CHIKF) burden in RS between 2017-2021.

FINDINGS

We detected an increasing CHIKF burden linked to travel associated introductions and communitary transmission of distinct lineages of the ECSA genotype during this period.

MAIN CONCLUSIONS

Until 2020, CHIKV introductions were most travel associated and transmission was limited. Then, in 2021, the largest outbreak occurred in the state associated with the introduction of a new ECSA lineage. CHIKV outbreaks are likely to occur in the near future due to abundant competent vectors and a susceptible population, exposing more than 11 million inhabitants to an increasing infection risk.

Global geotemporal distribution of chikungunya disease, 2011-2022

BACKGROUND

Chikungunya virus is a mosquito-borne alphavirus, transmitted by Aedes mosquitoes. Humans serve as the primary reservoir. Chikungunya infections typically appear with an abrupt onset of fever, rash, and severe joint pain. Some 40% of cases develop chronic rheumatologic complications that can persist months to years.

OBJECTIVES

To improve precision of risk characterization by analyzing cases of chikungunya by year and by country and depicting this geotemporal distribution in map form.

METHOD

Chikungunya case counts by year were compiled from national or regional health authorities from 2011 to 2022. These data were augmented by published reviews plus the Program for Monitoring Emerging Diseases (ProMED). Country-level distribution was categorized into four groups based on recency and magnitude. Data for India were mapped on a per-state basis.

RESULTS

The global map depicts distribution of chikungunya disease from 2011 through 2022. Most cases are reported in tropical and subtropical areas, but notable exceptions include the northern coast of the Mediterranean Sea. Countries of high recency and frequency include India, Brazil, Sudan, and Thailand. Countries with high frequency, but few cases reported in 2019-22 include many Latin American and Caribbean countries. Subnational foci are discussed in general and mapped for India. The range of Aedes mosquitoes is broader than the geography where chikungunya infection is typically diagnosed.

CONCLUSIONS

These maps help identify geographical regions where residents or travelers are at greatest risk of chikungunya. Once vaccines are licensed to help prevent chikungunya, maps like these can help guide future vaccine decision-making.

A booster regime of liposome-delivered live-attenuated CHIKV vaccine RNA genome protects against chikungunya virus disease in mice

Mosquito-transmitted chikungunya virus (CHIKV) is the causal pathogen of CHIKV disease and is responsible for global epidemics of arthritic disease. CHIKV infection can lead to severe chronic and debilitating arthralgia, significantly impacting patient mobility and quality of life. Our previous studies have shown a live-attenuated CHIKV vaccine candidate, CHIKV-NoLS, to be effective in protecting against CHIKV disease in mice vaccinated with one dose. Further studies have demonstrated the value of a liposome RNA delivery system to deliver the RNA genome of CHIKV-NoLS directly in vivo, promoting de novo production of live-attenuated vaccine particles in vaccinated hosts. This system, designed to bypass live-attenuated vaccine production bottlenecks, uses CAF01 liposomes. However, one dose of CHIKV-NoLS CAF01 failed to provide systemic protection against CHIKV challenge in mice, with low levels of CHIKV-specific antibodies. Here we describe CHIKV-NoLS CAF01 booster vaccination regimes designed to increase vaccine efficacy. C57BL/6 mice were vaccinated with three doses of CHIKV-NoLS CAF01 either intramuscularly or subcutaneously. CHIKV-NoLS CAF01 vaccinated mice developed a systemic immune response against CHIKV that shared similarity to vaccination with CHIKV-NoLS, including high levels of CHIKV-specific neutralising antibodies in subcutaneously inoculated mice. CHIKV-NoLS CAF01 vaccinated mice were protected against disease signs and musculoskeletal inflammation when challenged with CHIKV. Mice given one dose of live-attenuated CHIKV-NoLS developed a long lasting protective immune response for up to 71 days. A clinically relevant CHIKV-NoLS CAF01 booster regime can overcome the challenges faced by our previous one dose strategy and provide systemic protection against CHIKV disease.

An Overview of Indian Biomedical Research on the Chikungunya Virus with Particular Reference to Its Vaccine, an Unmet Medical Need

Chikungunya virus (CHIKV) is an infectious agent spread by mosquitos, that has engendered endemic or epidemic outbreaks of Chikungunya fever (CHIKF) in Africa, South-East Asia, America, and a few European countries. Like most tropical infections, CHIKV is frequently misdiagnosed, underreported, and underestimated; it primarily affects areas with limited resources, like developing nations. Due to its high transmission rate and lack of a preventive vaccine or effective treatments, this virus poses a serious threat to humanity. After a 32-year hiatus, CHIKV reemerged as the most significant epidemic ever reported, in India in 2006. Since then, CHIKV-related research was begun in India, and up to now, more than 800 peer-reviewed research papers have been published by Indian researchers and medical practitioners. This review gives an overview of the outbreak history and CHIKV-related research in India, to favor novel high-quality research works intending to promote effective treatment and preventive strategies, including vaccine development, against CHIKV infection.

Innate immune response in patients with acute Chikungunya disease

Chikungunya disease (CHIKD) is an arbovirose that presents with high morbidity, mainly due to arthralgia. Inflammatory mediators including IL-6, IL-1β, GM-CSF and others have been implicated in the pathogenesis of CHIKD, whilst type I interferons can be associated with better outcomes. The role of pattern recognition receptors has been studied incompletely. Here, we evaluated the expression of RNA-specific PRRs, their adaptor molecules and downstream cytokines in acute CHIKD patients. Twenty-eight patients were recruited during the 3rd-5th day after the symptoms onset for clinical examination, peripheral blood collection and qRT-PCR analysis of PBMC to compare to the healthy control group (n = 20). We observed common symptoms of acute CHIKD, with fever, arthralgia, headache and myalgia being the most frequent. Compared with uninfected controls, acute CHIKV infection upregulates the expression of the receptors TLR3, RIG-I and MDA5, and also the adaptor molecule TRIF. Regarding cytokine expression, we found an upregulation of IL-6, IL-12, IFN-α, IFN-β and IFN-γ, which are related directly to the inflammatory or antiviral response. The TLR3-TRIF axis correlated with high expression of IL-6 and IFN-α. Interestingly, greater expression of MDA5, IL-12 and IFN-α was related to lower viral loads in CHIKD acute patients. Together, these findings help to complete the picture of innate immune activation during acute CHIKD, while confirming the induction of strong antiviral responses. Drawing the next steps in the understanding of the immunopathology and virus clearance mechanisms of CHIKD should be of utter importance in the aid of the development of effective treatment to reduce the severity of this debilitating disease.

Epidemiology and Economic Burden of Chikungunya: A Systematic Literature Review

Chikungunya (CHIK) is a re-emerging viral infection endemic in tropical and subtropical areas. While the typical clinical presentation is an acute febrile syndrome, long-term articular complications and even death can occur. This review characterizes the global epidemiological and economic burden of chikungunya. The search included studies published from 2007 to 2022 in MEDLINE, Embase, LILACS, and SciELO for a thorough evaluation of the literature. Rayyan software was used for data analysis, and data were summarized descriptively and reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Seventy-six publications were included. Chikungunya is widely distributed in the tropics, including Africa, Asia, South America, and Oceania/the Pacific Islands, and co-circulates with other simultaneous arboviruses such as DENV, ZIKV, and YFV. Chikungunya infection can lead to chronic articular manifestations with a significant impact on the quality of life in the long term. In addition, it generates absenteeism and economic and social losses and can cause fatal infections in vulnerable populations, mainly in high-risk patients with co-morbidities and at the extremes of age. Reported costs associated with CHIKV diseases are substantial and vary by region, age group, and public/private delivery of healthcare services. The chikungunya disease burden includes chronicity, severe infections, increased hospitalization risks, and associated mortality. The disease can impact the economy in several spheres, significantly affecting the health system and national economies. Understanding and measuring the full impact of this re-emerging disease is essential.

Vaccine development for mosquito-borne viral diseases

Mosquito-borne viral diseases are a group of viral illnesses that are predominantly transmitted by mosquitoes, including viruses from the Togaviridae and Flaviviridae families. In recent years, outbreaks caused by Dengue and Zika viruses from the Flaviviridae family, and Chikungunya virus from the Togaviridae family, have raised significant concerns for public health. However, there are currently no safe and effective vaccines available for these viruses, except for CYD-TDV, which has been licensed for Dengue virus. Efforts to control the transmission of COVID-19, such as home quarantine and travel restrictions, have somewhat limited the spread of mosquito-borne viral diseases. Several vaccine platforms, including inactivated vaccines, viral-vector vaccines, live attenuated vaccines, protein vaccines, and nucleic acid vaccines, are being developed to combat these viruses. This review analyzes the various vaccine platforms against Dengue, Zika, and Chikungunya viruses and provides valuable insights for responding to potential outbreaks.

Chikungunya fever

Chikungunya virus is widespread throughout the tropics, where it causes recurrent outbreaks of chikungunya fever. In recent years, outbreaks have afflicted populations in East and Central Africa, South America and Southeast Asia. The virus is transmitted by Aedes aegypti and Aedes albopictus mosquitoes. Chikungunya fever is characterized by severe arthralgia and myalgia that can persist for years and have considerable detrimental effects on health, quality of life and economic productivity. The effects of climate change as well as increased globalization of commerce and travel have led to growth of the habitat of Aedes mosquitoes. As a result, increasing numbers of people will be at risk of chikungunya fever in the coming years. In the absence of specific antiviral treatments and with vaccines still in development, surveillance and vector control are essential to suppress re-emergence and epidemics.

Evolution and immunopathology of chikungunya virus informs therapeutic development

Chikungunya virus (CHIKV), a mosquito-borne alphavirus, is an emerging global threat identified in more than 60 countries across continents. The risk of CHIKV transmission is rising due to increased global interactions, year-round presence of mosquito vectors, and the ability of CHIKV to produce high host viral loads and undergo mutation. Although CHIKV disease is rarely fatal, it can progress to a chronic stage, during which patients experience severe debilitating arthritis that can last from several weeks to months or years. At present, there are no licensed vaccines or antiviral drugs for CHIKV disease, and treatment is primarily symptomatic. This Review provides an overview of CHIKV pathogenesis and explores the available therapeutic options and the most recent advances in novel therapeutic strategies against CHIKV infections.

The protein disulfide isomerase inhibitor 3-methyltoxoflavin inhibits Chikungunya virus

Chikungunya virus (CHIKV) is the etiological agent of chikungunya fever, a (re)emerging arbovirus infection, that causes severe and often persistent arthritis, as well as representing a serious health concern worldwide for which no antivirals are currently available. Despite efforts over the last decade to identify and optimize new inhibitors or to reposition existing drugs, no compound has progressed to clinical trials for CHIKV and current prophylaxis is based on vector control, which has shown limited success in containing the virus. Our efforts to rectify this situation were initiated by screening 36 compounds using a replicon system and ultimately identified the natural product derivative 3-methyltoxoflavin with activity against CHIKV using a cell-based assay (EC50 200 nM, SI = 17 in Huh-7 cells). We have additionally screened 3-methyltoxoflavin against a panel of 17 viruses and showed that it only additionally demonstrated inhibition of the yellow fever virus (EC50 370 nM, SI = 3.2 in Huh-7 cells). We have also showed that 3-methyltoxoflavin has excellent in vitro human and mouse microsomal metabolic stability, good solubility and high Caco-2 permeability and it is not likely to be a P-glycoprotein substrate. In summary, we demonstrate that 3-methyltoxoflavin has activity against CHIKV, good in vitro absorption, distribution, metabolism and excretion (ADME) properties as well as good calculated physicochemical properties and may represent a valuable starting point for future optimization to develop inhibitors for this and other related viruses.

Educational intervention for the control of Aedes aegypti with Wolbachia in Yucatan, Mexico

The implementation of new control strategies for Aedes aegypti (Ae. Aegpyti), a vector of dengue, chikungunya, and Zika viruses, requires communities to adopt specific behaviors to achieve the success of these innovations.

AIM

We evaluated the effect of an educational intervention based on the Precede-Proceed Model (PPM) and the Diffusion of Innovations Theory (DIT) for the control and prevention of diseases transmitted by Ae. aegypti through release of male mosquitoes infected with Wolbachia bacteria in a suburban town in Yucatan, Mexico.

MATERIAL AND METHODS

From July 2019 to February 2020, a quasi-experimental study was carried out through an educational intervention (pre- and post-measurements) using quantitative-qualitative techniques, in a Yucatan suburban town where male mosquitoes with Wolbachia were released for the suppression of Ae. aegypti populations. Eleven educational workshops were attended by heads of household (n = 19) and schoolchildren (n = 11). Other 136 heads of household not attending the workshops received information individually.

RESULTS

The educational intervention had a significant effect on the mean scores of the contributing and behavioral factors for adoption of innovation (p < 0.05) in the pre- and post-intervention measurements.

CONCLUSION

Innovative methods for the control and prevention of diseases related to Aedes aegypti can be strengthened through educational interventions supported by sound methodologies.

DESCRIPTORS

Community health education, Aedes aegypti, Wolbachia, Mexico.

Tumour necrosis factor plays a deleterious role in the pathogenesis of chikungunya virus infection

Arthralgia is a hallmark of chikungunya virus (CHIKV) infection and can be very debilitating and associated with a robust local inflammatory response. Many pathophysiological aspects associated with the disease remain to be elucidated. Here, we describe a novel model of CHIKV infection in immunocompetent mice and evaluate the role of tumour necrosis factor in the pathogenesis of the disease. C57BL/6 wild type (WT) or TNF receptor 1 deficient (TNFR1^-/- ) mice were inoculated with 1 × 10⁶ PFU of CHIKV in the paw. Alternatively, etanercept was used to inhibit TNF in infected WT mice. Hypernociception, inflammatory and virological analysis were performed. Inoculation of CHIKV into WT mice induced persistent hypernociception. There was significant viral replication in target organs and local production of inflammatory mediators in early time-points after infection. CHIKV infection was associated with specific humoral IgM and IgG responses. In TNFR1^-/- mice, there was a decrease in the hypernociception threshold, which was associated with a milder local inflammatory response in the paw but delayed viral clearance. Local or systemic treatment with etanercept reduced CHIKV-induced hypernociception. This is the first study to describe hypernociception, a clinical correlation of arthralgia, in immunocompetent mice infected with CHIKV. It also demonstrates the dual role of TNF in contributing to viral clearance but driving tissue damage and hypernociception. Inhibition of TNF may have therapeutic benefits but its role in viral clearance suggests that viral levels must be monitored in CHIKV-infected patients and that TNF inhibitors should ideally be used in combination with anti-viral drugs.

Identification of Potential Antiviral Hops Compounds against Chikungunya Virus

Chikungunya virus (CHIKV) is an arthropod-borne virus that belongs to the genus Alphavirus (family Togaviridae). CHIKV causes chikungunya fever, which is mostly characterized by fever, arthralgia and, sometimes, a maculopapular rash. The bioactive constituents of hops (Humulus lupulus, Cannabaceae), mainly acylphloroglucinols, known as well as α- and β-acids, exerted distinct activity against CHIKV, without showing cytotoxicity. For fast and efficient isolation and identification of such bioactive constituents, a silica-free countercurrent separation method was applied. The antiviral activity was determined by plaque reduction test and was visually confirmed by a cell-based immunofluorescence assay. All hops compounds demonstrated a promising post-treatment viral inhibition, except the fraction of acylphloroglucinols, in mixture. β-acids fraction of 125 µg/mL expressed the strongest virucidal activity (EC50 = 15.21 µg/mL), in a drug-addition experiment on Vero cells. Hypothesis for mechanism of action were proposed for acylphloroglucinols based on their lipophilicity and chemical structure. Therefore, inhibition of some steps of the protein kinase C (PKC) transduction cascades was also discussed.

Growth in chikungunya virus-related research in ASEAN and South Asian countries from 1967 to 2022 following disease emergence: a bibliometric and graphical analysis

BACKGROUND

ASEAN (Association of Southeast Asian Nations) is composed of ten Southeast Asian countries bound by socio-cultural ties that promote regional peace and stability. South Asia, located in the southern subregion of Asia, includes nine countries sharing similarities in geographical and ethno-cultural factors. Chikungunya is one of the most significant problems in Southeast and South Asian countries. Much of the current chikungunya epidemic in Southeast Asia is caused by the emergence of a virus strain that originated in Africa and spread to Southeast Asia. Meanwhile, in South Asia, three confirmed lineages are in circulation. Given the positive correlation between research activity and the improvement of the clinical framework of biomedical research, this article aimed to examine the growth of chikungunya virus-related research in ASEAN and South Asian countries.

METHODS

The Scopus database was used for this bibliometric analysis. The retrieved publications were subjected to a number of analyses, including those for the most prolific countries, journals, authors, institutions, and articles. Co-occurrence mapping of terms and keywords was used to determine the current state, emerging topics, and future prospects of chikungunya virus-related research. Bibliometrix and VOSviewer were used to analyze the data and visualize the collaboration network mapping.

RESULTS

The Scopus search engine identified 1280 chikungunya-related documents published by ASEAN and South Asian countries between 1967 and 2022. According to our findings, India was the most productive country in South Asia, and Thailand was the most productive country in Southeast Asia. In the early stages of the study, researchers investigated the vectors and outbreaks of the chikungunya virus. In recent years, the development of antivirus agents has emerged as a prominent topic.

CONCLUSIONS

Our study is the first to present the growth of chikungunya virus-related research in ASEAN and South Asian countries from 1967 to 2022. In this study, the evaluation of the comprehensive profile of research on chikungunya can serve as a guide for future studies. In addition, a bibliometric analysis may serve as a resource for healthcare policymakers.

Probing RNA Conformations Using a Polymer-Electrolyte Solid-State Nanopore

Nanopore systems have emerged as a leading platform for the analysis of biomolecular complexes with single-molecule resolution. The conformation of biomolecules, such as RNA, is highly dependent on the electrolyte composition, but solid-state nanopore systems often require high salt concentration to operate, precluding analysis of macromolecular conformations under physiologically relevant conditions. Here, we report the implementation of a polymer-electrolyte solid-state nanopore system based on alkali metal halide salts dissolved in 50% w/v poly(ethylene) glycol (PEG) to augment the performance of our system. We show that polymer-electrolyte bath governs the translocation dynamics of the analyte which correlates with the physical properties of the salt used in the bath. This allowed us to identify CsBr as the optimal salt to complement PEG to generate the largest signal enhancement. Harnessing the effects of the polymer-electrolyte, we probed the conformations of the Chikungunya virus (CHIKV) RNA genome fragments under physiologically relevant conditions. Our system was able to fingerprint CHIKV RNA fragments ranging from ∼300 to ∼2000 nt length and subsequently distinguish conformations between the co-transcriptionally folded and the natively refolded ∼2000 nt CHIKV RNA. We envision that the polymer-electrolyte solid-state nanopore system will further enable structural and conformational analyses of individual biomolecules under physiologically relevant conditions.