Chikungunya fever: epidemiology, clinical syndrome, pathogenesis and therapy

IFITMs exhibit antiviral activity against Chikungunya and Zika virus infection via the alteration of TLRs and RLRs signaling pathways

Chikungunya virus (CHIKV) poses a significant challenge as there are currently no targeted antiviral drugs or vaccines to combat this infection. Here, we demonstrate that interferon-induced transmembrane proteins (IFITMs), including IFITM1, IFITM2, and IFITM3, which are interferon-stimulated genes (ISGs), inhibit CHIKV infection in human skin fibroblasts. Overexpression of IFITMs in cells restricts viral infection, whereas knockdown of IFITMs enhances viral infection. IFITMs overexpression causes a substantial upregulation of antiviral genes, namely TLR3, TLR7, TLR8, and TLR9, and their downstream signaling molecules such as TRADD, IRAK1, TRAF6, and MAP3K7, involved in TLRs signaling pathways. Furthermore, the DHX58 gene encoding the LGP2 protein, a negative regulator of RIG-I in RLRs signaling pathways, was downregulated in the overexpressed cells. Transcription factors including interferon regulatory factors (IRF) 3/5/7, which are downstream signaling components of both TLR and RLR signaling pathways, were also upregulated, resulting in enhanced IFNs signaling. IFITMs not only inhibits the early and late stages of viral infection but can also alter the antiviral innate-immune response to restrict CHIKV infection in human skin fibroblasts. Additionally, IFITMs exhibit their antiviral activity against Zika virus (ZIKV). Altogether, these results show the broad-spectrum antiviral property of IFITMs against arboviruses in foreskin cells.

Viral Kinetics During Acute Chikungunya Virus Infection: Insights Into Potential Role of Monoclonal Antibodies in Viral Clearance and Prophylaxis Using Mathematical Modeling

Chikungunya virus (CHIKV), an arthritogenic alphavirus, is a significant public health threat in endemic and newly affected regions. This study investigates viral kinetics, immune responses, and the potential of monoclonal antibody (mAb) therapies to mitigate viraemia and transmission during acute CHIKV infection, providing novel insights into early intervention strategies. Using data from 29 patients in Cambodia, serial sampling and viral load quantification revealed that the population-average peak viral load occurred ~1.87 days prior to symptom onset. Children demonstrated higher peak viral loads and faster replication rates compared to adults, although symptom severity and burden were similar across age groups. IgM antibodies appeared earlier in adults (median: 4.1 days) than in children (median: 5.1 days; p = 0.036). C-reactive protein (CRP) levels were transiently elevated in about 50% of patients but showed no correlation with disease severity. Mathematical modeling highlighted that prophylactic mAb therapies, when administered 3 days before symptoms onset, could substantially reduce viral load and potentially prevent detectable viraemia. While these findings underscore the potential of mAbs as an early therapeutic strategy, further studies are necessary to evaluate the robustness of these results and assess their practical implications to curb CHIKV outbreaks by minimizing viraemia and presymptomatic transmission.

Phylogenetic Analysis of Chikungunya Virus Eastern/Central/South African-Indian Ocean Epidemic Strains, 2004-2019

CHIKV infection is transmitted by Aedes mosquitoes spp., with Ae. aegypti considered as the primary vector and Ae. Albopictus playing an important role in sustaining outbreaks in Europe. The ECSA-Indian Ocean Lineage (IOL) strain emerged in Reunion, subsequently spreading to areas such as India, the Indian Ocean, and Southeast Asia, also causing outbreaks in naive countries, including more temperate regions, which originated from infected travelers. In Italy, two authocthounous outbreaks occurred in 2007 (Emilia Romagna region) and 2017 (Lazio and Calabria regions), caused by two different ECSA-IOL strains. The phylogenetics, evolution, and phylogeography of ECSA-IOL-CHIKV strains causing the 2007 and 2017 outbreaks in Italy were investigated. The mean evolutionary rate and time-scaled phylogeny were performed through BEAST. Specific adaptive vector mutations or key signature substitutions were also investigated. The estimated mean value of the CHIKV E1 evolutionary rate was 1.313 × 10-3 substitution/site/year (95% HPD: 8.709 × 10-4-1.827 × 10-3). The 2017 CHIKV Italian sequences of the outbreak in Lazio and of the secondary outbreak in Calabria were located inside a sub-clade dating back to 2015 (95% HPD: 2014-2015), showing an origin in India. Continued genomic surveillance combined with phylogeographic analysis could be useful in public health, as a starting point for future risk assessment models and early warning.

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.

Unmasking Hepatitis A: A Case Study of Atypical Presentation in a Returning Traveler From Egypt

Hepatitis, characterized by inflammation of the liver, arises from various infectious and noninfectious causes, with viral hepatitis being caused by a diverse group of viruses including hepatitis A, B, C, D, and E. Infection with the Hepatitis A virus (HAV) can result in liver inflammation and damage, primarily spread through fecal-oral contamination. Clinical symptoms often overlap with other infections, complicating diagnosis in returning travelers from endemic regions. This case study focuses on a 46-year-old Sudanese housewife who presented with symptoms of fever, chills, headache, and muscle aches, along with a high temperature of 103.5°F, following a recent visit to Egypt. The initial assessment showed hemodynamic stability and abnormal liver function tests. This raise suspicion about the potential involvement of several infections including malaria, hepatitis, arboviral diseases such as Chikungunya, Yellow, and dengue fevers. Further investigations revealed acute hepatitis A infection confirmed through positive serology. Notably, the patient displayed atypical features such as atypical lymphocytosis, splenomegaly, and mild anemia. This case emphasizes the significance of essentially considering a wide range of diseases among travelers including hepatitis A among people coming from highly endemic areas such as Egypt, even when the patient is not manifested with the typical clinical presentation of specific disease. Particular attention is needed for epidemic-prone infections like hepatitis A.

Infectomics of Chikungunya Virus: Roles Played by Host Factors

Chikungunya virus (CHIKV), prevalent in tropical regions, is known for causing frequent outbreaks, particularly in Central Africa, South America, and Southeast Asia. It is an arbovirus transmitted by the Aedes (Ae.) aegypti and Ae. albopictus mosquitoes. Infections lead to severe joint and muscle pain, which can linger and significantly impair an individual's health, quality of life, and economic stability. Recent climatic changes and the globalization of travel have facilitated the worldwide spread of these mosquitoes. Currently, no U.S. Food and Drug Administration (FDA) approved drug is available for treating CHIKV infection. Recently, the FDA approved a live, attenuated vaccine called Ixchiq. However, this vaccine has been linked to side effects, leading the FDA to mandate additional post-marketing studies to assess the risk of severe adverse reactions similar to the virus. An emerging strategy in drug development focuses on targeting host factors that the virus exploits rather than the viral proteins themselves. This review explores the interactions between CHIKV and host factors that could be potential therapeutic targets. Despite progress in understanding the life cycle of CHIKV, the immune system's role in combating the virus still needs to be fully understood. Investigating treatments that enhance the host's immune response may offer new paths to combating CHIKV.

Attenuation of Chikungunya Virus by a Single Amino Acid Substitution in the nsP1 Component of a Non-Structural Polyprotein

Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus that, since its re-emergence in 2004, has become recognised as a major public health concern throughout many tropical and sub-tropical regions of the world. Amongst the insights gained from studies on other alphaviruses, several key determinants of virulence have been identified, including one present at the P3 position in the nsP1/nsP2 cleavage domain of the S.A.AR86 Sindbis (SINV) strain. This strain is associated with neurovirulence in adult mice; however, when a threonine-to-isoleucine substitution is engineered at this P3 position, an attenuated phenotype results. A reverse genetics system was developed to evaluate the phenotype that resulted from the substitution of alanine, present at the P3 position in the wild-type CHIKV clone, with valine. The A533V-mutant CHIKV induced milder disease symptoms in the C57BL/6 mouse model than the wild-type virus, in terms of severity of inflammation, length of viraemic period, and histological changes. Furthermore, the induction of type I IFN occurred more rapidly in both CHIKV-infected cell cultures and the mouse model with the mutant CHIKV.

Clinical manifestations associated with the chronic phase of Chikungunya Fever: A systematic review of prevalence

INTRODUCTION

The aim of this systematic review of prevalence is to observe and discuss the clinical manifestations of Chikungunya Virus disease in its chronic phase.

METHODS

To be eligible, the observational studies should accompany the individuals for at least six months. The research was conducted using electronic databases MEDLINE and EMBASE. The methodological quality was evaluated using the "Joanna Briggs Institute's critical appraisal checklist for studies reporting prevalence data" tool.

RESULTS

The search has found 175 articles. The application of the inclusion criteria defined a total of 29 selected studies. From the included studies, only one did not present arthralgia as a prevalent symptom in the chronic phase. Other signs and symptoms observed were: fatigue; sleep disorders; myalgia; skin lesions; depression; digestive disorders.

CONCLUSION

Because it is an often incapacitating symptom, arthralgia can affect the individuals' quality of life, with implications in their social and work life. Since the chronic phase is common in infected individuals, all levels of health care should be prepared to monitor, in the medium to long term, the patients affected by this condition.

Safety and immunogenicity of a live-attenuated chikungunya virus vaccine in endemic areas of Brazil: interim results of a double-blind, randomised, placebo-controlled phase 3 trial in adolescents

BACKGROUND

Chikungunya outbreaks have been reported in Brazil since 2014. Adolescents are a sensitive population who would benefit from a prophylactic vaccine. This study assessed the immunogenicity and safety of the vaccine VLA1553 in adolescents in Brazil. With an overall trial duration of 12 months, we now report data on safety and immunogenicity over a period of 28 days after vaccination.

METHODS

In this double-blind, randomised, placebo-controlled phase 3 trial, adolescents aged 12 to <18 years were recruited. The trial was performed at ten trial sites across Brazil. Eligible participants were generally healthy. The main exclusion criteria comprised immune-mediated or chronic arthritis or arthralgia, a known or suspected defect of the immune system, or any live vaccine received within the 4 weeks before trial vaccination. Randomisation was stratified by baseline serostatus in a 2:1 ratio to receive VLA1553 (at a dose of 1 × 104 TCID50 per 0·5 mL [ie, 50% tissue culture infectious dose]) or placebo. VLA1553 or placebo was administered intramuscularly as a single-dose immunisation on day 1. The primary endpoint was the proportion of baseline seronegative participants with chikungunya virus neutralising antibody levels of 150 or more in μPRNT50 (a micro plaque reduction neutralisation test), which was considered a surrogate of protection. The safety analysis included all participants receiving a trial vaccination. Immunogenicity analyses were performed in a subset. The trial is registered with ClinicalTrials.gov, NCT04650399.

FINDINGS

Between Feb 14, 2022, and March 14, 2023, 754 participants received a trial vaccination (502 received VLA1553 and 252 received placebo) with a per-protocol population of 351 participants for immunogenicity analyses (303 in the VLA1553 group and 48 in the placebo group). In participants who were seronegative at baseline, VLA1553 induced seroprotective chikungunya virus neutralising antibody levels in 247 of 250 (98·8%, 95% CI 96·5-99·8) participants 28 days after vaccination. In seropositive participants, the baseline seroprotection rate of 96·2% increased to 100% after vaccination with VLA1553. Most (365 [93%] of 393) adverse events were of mild or moderate intensity, VLA1553 was generally well tolerated. When compared with placebo, participants exposed to VLA1553 had a significantly higher frequency of related adverse events (351 [69·9%] of 502 vs 121 [48·0%] of 252; p<0·0001), mostly headache, myalgia, fatigue, and fever. Among four reported serious adverse events (three in the VLA1553 group and one in the placebo group), one was classified as possibly related to VLA1553: a high-grade fever. Among 20 adverse events of special interest (ie, symptoms suggesting chikungunya-like disease), 16 were classified as related to trial vaccination (15 in the VLA1553 group and one in the placebo group), with severe symptoms reported in four participants (fever, headache, or arthralgia). 17 adverse events of special interest resolved within 1 week. Among 85 participants with arthralgia (68 in the VLA1553 group and 17 in the placebo group), eight adolescents had short-lived (range 1-5 days), mostly mild recurring episodes (seven in the VLA1553 group and one in the placebo group). The median duration of arthralgia was 1 day (range 1-5 days). The frequency of injection site adverse events for VLA1553 was higher than in the placebo group (161 [32%] vs 62 [25%]), but rarely severe (two [<1%] in the VLA1553 group and one [<1%] in the placebo group). After administration of VLA1553, there was a significantly lower frequency of solicited adverse events in participants who were seropositive at baseline compared with those who were seronegative (53% vs 74%; p<0·0001) including headache, fatigue, fever, and arthralgia.

INTERPRETATION

VLA1553 was generally safe and induced seroprotective titres in almost all vaccinated adolescents with favourable safety data in adolescents who were seropositive at baseline. The data support the use of VLA1553 for the prevention of disease caused by the chikungunya virus among adolescents and in endemic areas.

FUNDING

Coalition for Epidemic Preparedness Innovation and EU Horizon 2020.

TRANSLATION

For the Portuguese translation of the abstract see Supplementary Materials section.

4-Substituted-2-Thiazole Amides as Viral Replication Inhibitors of Alphaviruses

2-(Methylthio)-N-(4-(naphthalen-2-yl)thiazol-2-yl)nicotinamide 1 was identified as an inhibitor against Chikungunya virus (CHIKV) with good antiviral activity [EC50 = 0.6 μM; EC90 = 0.93 μM and viral titer reduction (VTR) of 6.9 logs at 10 μM concentration] with no observed cytotoxicity (CC50 = 132 μM) in normal human dermal fibroblast (NHDF) cells. Structure-activity relationship (SAR) studies to further improve the potency, efficacy, and drug-like properties of 1 led to the discovery of a new potent inhibitor N-(4-(3-((4-cyanophenyl)amino)phenyl)thiazol-2-yl)-2-(methylthio)nicotinamide 26, which showed a VTR of 8.7 logs at 10 μM against CHIKV and an EC90 of 0.45 μM with considerably improved MLM stability (t1/2 = 74 min) as compared to 1. Mechanism of action studies show that 26 inhibits alphavirus replication by blocking subgenomic viral RNA translation and structural protein synthesis. The in vivo efficacy studies of compound 26 on CHIKV infection in mice are reported.

The global health and economic burden of chikungunya from 2011 to 2020: a model-driven analysis on the impact of an emerging vector-borne disease

INTRODUCTION

Chikungunya is a mosquito-borne arboviral disease posing an emerging global public health threat. Understanding the global burden of chikungunya is critical for designing effective prevention and control strategies. However, current estimates of the economic and health impact of chikungunya remain limited and are potentially underestimated. This study aims to provide a comprehensive overview of the chikungunya burden worldwide.

METHODS

We analysed the global burden of chikungunya between 2011 and 2020 and calculated disability-adjusted life years (DALYs) and direct and indirect costs using a data-driven simulation model. The main outcomes were the number of cases, the total DALY burden, and the direct and indirect costs of acute and chronic chikungunya between 2011 and 2020.

RESULTS

Our study revealed a total of 18.7 million chikungunya cases in 110 countries between 2011 and 2020, causing 1.95 million DALYs. Most of this burden was found in the Latin American and Caribbean region. The total economic burden caused by chikungunya over these 10 years was estimated at $2.8 billion in direct costs and $47.1 billion in indirect costs worldwide. Long-term chronic illness was the source of most costs and DALYs.

CONCLUSION

Chikungunya has a higher disease burden than was previously estimated and costs related to the disease are substantial. Especially in combination with its unpredictable nature, chikungunya could significantly impact local health systems. Insights from this study could inform decision makers on the impact of chikungunya on population health and help them to appropriately allocate resources to protect vulnerable populations from this debilitating disease.

Acute Immunological Profile and Prognostic Biomarkers of Persistent Joint Pain in Chikungunya Fever: A Systematic Review

Chikungunya virus infection (CHIKV) increases the risk of persistent arthralgia; however, there is no consistent evidence regarding prognostic biomarkers of progression to chronic arthropathy. This systematic review provides an overview of currently available literature about the potential role of the acute immunologic response in predicting long-term joint pain in patients with a diagnosis of CHIKV. We searched for observational studies using the terms "chikungunya," "cytokines," "biomarkers," and "joint pain" in PubMed/MEDLINE, LILACS, Cochrane Library Plus, and SCOPUS databases, restricting to articles published in English and up to April 2024. PROSPERO registration number: CRD42021279400. Thirty-eight studies were selected for qualitative synthesis with a maximum duration from diagnosis to clinical evaluation of 60 months. The sample sizes ranged from 8 to 346 participants (age range: 0-90 years). We identified an immunologic profile during the acute phase of CHIKV that includes increased levels of proinflammatory cytokines (IFN-α, IFN-γ, IL-2R, IL-6, IL-7, and IL-8), anti-inflammatory cytokines (IL-1Ra and IL-4), chemokines (MCP-1, MIG, and IP-10) and growth factors (VEGF and G-CSF). Only one out of two studies reported differences in cytokine levels during the acute phase, predicting persistent joint pain at 20 months of follow-up. Also, persistence of anti-CHIKV IgG seemed to be a potential prognostic marker. The evidence suggests the existence of an inflammatory response in the acute phase of CHIKV that persists during its chronic phase; however, there is no unequivocal candidate set of biomarkers of progression toward long-term articular sequelae.

Host-adaptive mutations in Chikungunya virus genome

Chikungunya virus (CHIKV) is the causative agent of chikungunya fever (CHIKF), and its primary vectors are the mosquitoes Aedes aegypti and Aedes albopictus. CHIKV was initially endemic to Africa but has spread globally in recent years and affected millions of people. According to a risk assessment by the World Health Organization, CHIKV has the potential seriously impact public health. A growing body of research suggests that mutations in the CHIKV gene that enhance viral fitness in the host are contributing to the expansion of the global CHIKF epidemic. In this article, we review the host-adapted gene mutations in CHIKV under natural evolution and laboratory transmission conditions, which can help improve our understanding of the adaptive evolution of CHIKV and provide a basis for monitoring and early warning of future CHIKV outbreaks.

Strategic vaccination responses to Chikungunya outbreaks in Rome: Insights from a dynamic transmission model

BACKGROUND

Chikungunya virus (CHIKV) outbreaks, driven by the expanding habitat of the Aedes albopictus mosquito and global climate change, pose a significant threat to public health. Our study evaluates the effectiveness of emergency vaccination using a dynamic disease transmission model for a potential large-scale outbreak in Rome, Italy.

METHODS

The model incorporates a susceptible-exposed-infected-recovered (SEIR) framework for human and mosquito populations, taking into account temperature-dependent mosquito lifecycle dynamics, human-mosquito interactions, and various vaccination scenarios.

FINDINGS

Results indicate that emergency vaccination could significantly mitigate the impact of a CHIKV outbreak. Without vaccination, an outbreak is estimated to infect up to 6.21% of Rome's population, equating to approximately 170,762 individuals. Implementing rapid vaccination after detecting the virus in ten individuals and achieving 40% coverage could reduce infection rates by 82%, preventing 139,805 cases. Scenario and sensitivity analyses confirm that even with lower vaccination coverage rates, significant benefits are observed: at 10% coverage, the number of infections drops to 115,231, and at 20% coverage, it further reduces to 76,031. These scenarios indicate prevention of approximately 33% and 55% of infections, respectively.

CONCLUSIONS

The findings highlight the critical role of timely vaccination interventions in outbreak settings, demonstrating that even modest coverage levels can markedly decrease the spread of CHIKV. This study underscores the importance of preparedness, early detection and adaptive response capabilities to manage emerging infectious diseases in urban centres, advocating for strategic vaccine stockpiling and rapid deployment mechanisms to enhance public health outcomes.

Current Epidemiological Status of Chikungunya Virus Infection in East Africa: A Systematic Review and Meta-Analysis

Background: The incidence of Chikungunya in tropical Africa is still of major epidemiological significance. This study aims to determine the prevalence of chikungunya in East Africa through a systematic review and meta-analysis of published studies. Methods: We conducted a comprehensive search across six electronic databases-Web of Science, PubMed, ScienceDirect, Scopus, and Google Scholar-using specific keywords to address the worldwide impact of chikungunya following the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines. A meta-analysis was performed on our eligible studies using the random effect model. Results: Our search returned 40 eligible articles involving 4122 Chikungunya cases in 13 East African nations. These studies, conducted between 2014 and 2024 across 13 East African nations, provided diverse data on chikungunya prevalence. The overall pooled prevalence of chikungunya in East Africa was 20.6% (95% CI: 18.8%-22.5% and I 2 = 99.62%). Subgroup analyses revealed variations in prevalence across different countries, study designs, detection methods, and publication years. Notably, Rwanda and Djibouti exhibited high prevalence rates of 63.0% and 50.4%, respectively, while Kenya and Somalia reported a moderate prevalence of 12.2%. The detection methods also influenced prevalence rates, with RT-PCR studies indicating a higher prevalence (28.3%) compared to ELISA (19.3%). Conclusion: The study highlights the significant burden of chikungunya in East Africa, and the findings underscore the need for targeted public health interventions and improved surveillance to manage and control chikungunya outbreaks in the region.

Chronic Rheumatologic Disease in Chikungunya Virus Fever: Results from a Cohort Study Conducted in Piedecuesta, Colombia

This study aimed to determine the incidence of post-chikungunya chronic rheumatism (pCHIK-CR) and its impact on quality of life (QoL) and chronic fatigue in adults seven years after the 2014-2015 CHIKV outbreak in Piedecuesta, Colombia. We evaluated 78 adults (median age: 30 years, IQR: 21.0; women 60.3%) with confirmed CHIKV infection. In 2022, participants underwent a GALS examination and completed surveys on disability, stiffness, health status, and fatigue. A rheumatologist evaluated patients who reported arthralgia, morning stiffness, and abnormal GALS examination. Chronic fatigue was defined as fatigue persisting for over six months. Seven years after infection, 14.1% of participants were classified as pCHIK-CR cases, 41.0% as having non-inflammatory pain, likely degenerative (NIP-LD), and 44.9% without rheumatic disease (Wo-RM). Patients with pCHIK-CR and NIP-LD exhibited significantly worse QoL compared to Wo-RM cases. Chronic fatigue prevalence increased from 8.6% in Wo-RM patients to 25.0% in NIP-LD and 54.6% in pCHIK-CR cases. This study implemented a comprehensive clinical assessment to objectively estimate and characterize the incidence of chronic rheumatological disease attributed to CHIKV infection. One in seven cases with CHIKV infection develops pCHIK-CR, which impacts both QoL and chronic fatigue. This study contributes to understanding the burden of these arboviruses in the medium term.

[Evidence map of chikungunya treatmentsMapa de la evidencia sobre el tratamiento del chikunguña]

Objective

Based on a review of the literature, to create a map of the available evidence on the treatment methods for chikungunya.

Method

In May 2022, a literature search on chikungunya was conducted using the PubMed and Virtual Health Library platforms. To create the evidence map, studies that mentioned chikungunya fever were selected and characterized based on the type of intervention, outcome, and direction of the effect (positive, negative, potentially positive or potentially negative, inconclusive, or no effect), following the methodology recommended by the Latin American and Caribbean Center on Health Sciences Information (BIREME).

Results

Fifteen studies (systematic reviews, controlled clinical trials, and narrative reviews) with both pharmacological and non-pharmacological interventions were included. All interventions focused on symptom mitigation; no study specifically investigated ways to combat the virus itself. Only one study on pharmacological interventions reported a positive effect, involving monotherapy with hydroxychloroquine and combined therapy with methotrexate plus sulfasalazine and hydroxychloroquine for reducing and relieving pain caused by post-chikungunya arthritis. The only study to report a negative effect described the use of chloroquine for post-chikungunya arthralgia. Among non-pharmacological interventions, positive effects were noted for transcranial direct current stimulation, elastic band exercises, and the Pilates method, particularly for pain relief and improvement of joint function.

Conclusion

Although the review did not identify any treatments that act directly on the virus after the onset of the disease, the evidence map suggests that it is possible to treat the symptoms and sequelae of chikungunya with both pharmacological and non-pharmacological therapies.

Outbreak of Chikungunya Fever in the Central Valley of Chiapas, Mexico

Chikungunya virus (CHIKV) was isolated from humans in an outbreak of a febrile illness during July and August 2015 in the central valleys of Chiapas, Mexico. Sera obtained from 80 patients were tested for CHIKV RNA by reverse transcriptase polymerase chain reaction (RT-PCR) and for IgM and IgG antibodies by an enzyme linked immunoassay and a commercial indirect immunofluorescence test for CHIKV and dengue virus (DENV). Of the 80 patients, 67 were positive, including 50 for RNA and 17 for IgM. In addition, one patient was coinfected with CHIKV-DENV and 40 patients were positive for IgG antibody to DENV. The clinical manifestations included a high fever, polyarthralgia, headache, myalgia, rash, digestive disorders, conjunctivitis, and adenopathy associated with cervical and axillary inguinal regions. Complete nucleotide sequences of two of the CHIKV isolates showed that they belonged to the Asian lineage but did not group with other Mexican CHIKV isolates from the Chiapas coast. Our findings documented that different Asian lineage strains of CHIKV were circulating simultaneously during the 2015 outbreak in the Central Valley of Chiapas, Mexico. The 2024 cases suggest an explosive scenario of re-emergence of thousands of new Chikungunya and dengue fever (DENF) cases associated with deaths, and a dangerous increase of the four DENV serotypes throughout the Americas, especially in South American countries that have shown a high influx of human migration to southern Mexico. In Mexico, the state of Chiapas and other southern regions are the most vulnerable.

Systemic and Ophthalmic Manifestations of Chikungunya Fever

PURPOSE

Chikungunya is a re-emerging viral infection across the globe. The purpose of this article is to review the systemic and ophthalmic manifestations associated with chikungunya fever.

METHOD

A review of literature was conducted using online databases.

RESULTS

In this report, we have reviewed the presently available literature on uveitis caused by chikungunya and highlighted the current knowledge of its clinical manifestations, imaging features, laboratory diagnostics, and the available therapeutic modalities from the systemic and ophthalmic standpoint.

CONCLUSIONS

Ocular involvement in chikungunya infection may occur at the time of systemic manifestations or it may occur as a delayed presentation many weeks after the fever. Treatment relies on a supportive therapy for systemic illness. Treatment of ocular manifestation depends on the type of manifestations and usually includes a combination of topical and oral steroids.

Development of a novel multi-epitope vaccine based on capsid and envelope protein against Chikungunya virus

Chikungunya virus (CHIKV), a type A virus borne by mosquitoes that can cause major clinical manifestations including rash, fever and debilitating arthritis, grown into a reemerging serious public health issue. Currently, there is no licensed therapy or vaccine available for CHIKV, although the most promising form of treatment appears to be immunotherapy. Neutralizing antibodies for CHIKV can provide high protection for all CHIKV strains, as well as other alphaviruses. Development of a protective vaccine may be an effective strategy to prevent the outbreak of CHIKV and provide protection for travelers. In this study, we designed a multi-epitope vaccine with a 543-amino-acid structure based on the E1, E2 and capsid proteins of CHIKV, including 6 CTL epitopes, 6 HTL epitopes, 12 linear B epitopes, along with the adjuvant β-defensin III. All T-cell epitopes were docked with their corresponding MHC alleles to validate their effect on inducing immune responses, and the vaccine's sequence was proven to have acceptable physicochemical properties. Further, the developed vaccine was docked with TLR3 and TLR8, both of which play an important role in recognizing RNA viruses. Basic analyses of the docked complexes and molecular dynamic simulations revealed that the vaccine interacted strongly with TLRs. Immunological simulations indicated that the vaccine could induce both cellular and humoral immunity. Hopefully, this proposed vaccine structure can serve as a viable candidate against CHIKV infection.Communicated by Ramaswamy H. Sarma.

Vaccine value profile for Chikungunya

Chikungunya virus (CHIKV) a mosquito-borne alphavirus is the causative agent of Chikungunya (CHIK), a disease with low mortality but high acute and chronic morbidity resulting in a high overall burden of disease. After the acute disease phase, chronic disease including persistent arthralgia is very common, and can cause fatigue and pain that is severe enough to limit normal activities. On average, around 40% of people infected with CHIKV will develop chronic arthritis, which may last for months or years. Recommendations for protection from CHIKV focus on infection control through preventing mosquito proliferation. There is currently no licensed antiviral drug or vaccine against CHIKV. Therefore, one of the most important public health impacts of vaccination would be to decrease burden of disease and economic losses in areas impacted by the virus, and prevent or reduce chronic morbidity associated with CHIK. This benefit would particularly be seen in Low and Middle Income Countries (LMIC) and socio-economically deprived areas, as they are more likely to have more infections and more severe outcomes. This 'Vaccine Value Profile' (VVP) for CHIK is intended to provide a high-level, holistic assessment of the information and data that are currently available to inform the potential public health, economic and societal value of vaccines in the development pipeline and vaccine-like products.This VVP was developed by a working group of subject matter experts from academia, non-profit organizations, public private partnerships, and multi-lateral organizations. All contributors have extensive expertise on various elements of the CHIK VVP and collectively aimed to identify current research and knowledge gaps.The VVP was developed using only existing and publicly available information.

Clinical profile and management of a Spanish single-center retrospective cohort of patients with post-chikungunya associated complications

BACKGROUND

This study aims to describe post-chikungunya complications chronically developed cases in returning travelers from some epidemic/endemic regions, and the variables that are associated with the progression of acute or subacute cases to the chronic phase.

METHODS

This single-center retrospective cohort study included chikungunya fever cases treated at La Paz-Carlos III University Hospital in Madrid, Spain, April 2014 to September 2016, when the chikungunya outbreak in Latin America started through the time of its greatest impact.

RESULTS

The analysis included 119 cases. Of these, 67.2 % were male, with a median age of 41.0 years [IQR 16.0 to 76.0] years. Only 25.6 % of the patients attended a pre-travel advice consultation. Most patients reported arthralgias, which significantly impacted their daily quality of life (86 %). The mean duration of joint symptoms was 129.4 days, with a median of 90 days [IQR 0 to 715]. Factors found to be associated with chronic arthralgia include female sex, country of infection, age at diagnosis, previous diseases, symptoms during the acute phase, pain in previously injured tendons/joints, acute phase severity, and various laboratory markers such as hemoglobin, hematocrit, total serum bilirubin, and creatinine. Progression to chronic arthralgia significantly increased the need for changes in daily activity. Furthermore, 42.6 % of patients with chronic arthralgia reported recurrence of symptoms once they felt they had disappeared. Targeted treatment regimens led to significant improvements in these patients.

CONCLUSIONS

The results of this study underscore the need for: (1) comprehensive pre-travel advice; (2) effective management of patients in specialized units, alongside early diagnosis and treatment, to prevent trivialization of these viral infections; and (3) the development of interdisciplinary recommendations to assist physicians in treating patients and enhancing outcomes.

Clinical outcomes of chikungunya: A systematic literature review and meta-analysis

BACKGROUND

Chikungunya is a viral disease caused by a mosquito-borne alphavirus. The acute phase of the disease includes symptoms such as fever and arthralgia and lasts 7-10 days. However, debilitating symptoms can persist for months or years. Despite the substantial impact of this disease, a comprehensive assessment of its clinical picture is currently lacking.

METHODS

We conducted a systematic literature review on the clinical manifestations of chikungunya, their prevalence and duration, and related hospitalization. Embase and MEDLINE were searched with no time restrictions. Subsequently, meta-analyses were conducted to quantify pooled estimates on clinical outcomes, the symptomatic rate, the mortality rate, and the hospitalization rate. The pooling of effects was conducted using the inverse-variance weighting methods and generalized linear mixed effects models, with measures of heterogeneity reported.

RESULTS

The systematic literature review identified 316 articles. Out of the 28 outcomes of interest, we were able to conduct 11 meta-analyses. The most prevalent symptoms during the acute phase included arthralgia in 90% of cases (95% CI: 83-94%), and fever in 88% of cases (95% CI: 85-90%). Upon employing broader inclusion criteria, the overall symptomatic rate was 75% (95% CI: 63-84%), the chronicity rate was 44% (95% CI: 31-57%), and the mortality rate was 0.3% (95% CI: 0.1-0.7%). The heterogeneity between subpopulations was more than 92% for most outcomes. We were not able to estimate all predefined outcomes, highlighting the existing data gap.

CONCLUSION

Chikungunya is an emerging public health concern. Consequently, a thorough understanding of the clinical burden of this disease is necessary. Our study highlighted the substantial clinical burden of chikungunya in the acute phase and a potentially long-lasting chronic phase. Understanding this enables health authorities and healthcare professionals to effectively recognize and address the associated symptoms and raise awareness in society.

Commonly Reported Mosquito-Borne Viruses in the United States: A Primer for Pharmacists

Mosquito-borne diseases are a public health concern. Pharmacists are often a patient's first stop for health information and may be asked questions regarding transmission, symptoms, and treatment of mosquito borne viruses (MBVs). The objective of this paper is to review transmission, geographic location, symptoms, diagnosis and treatment of MBVs. We discuss the following viruses with cases in the US in recent years: Dengue, West Nile, Chikungunya, LaCrosse Encephalitis, Eastern Equine Encephalitis Virus, and Zika. Prevention, including vaccines, and the impact of climate change are also discussed.

Unlocking the antiviral potential of rosmarinic acid against chikungunya virus via IL-17 signaling pathway

Background

The Chikungunya virus is an Alphavirus that belongs to the Togaviridae family and is primarily transmitted by mosquitoes. It causes acute infection characterized by fever, headache, and arthralgia. Some patients also experience persistent chronic osteoarthritis-like symptoms. Dedicated antiviral treatments are currently unavailable for CHIKV. This study aims to explore the potential anti-CHIKV effect of rosmarinic acid using network pharmacology.

Methods

This study employed network pharmacology to predict and verify the molecular targets and pathways associated with ROSA in the context of CHIKV. The analysis outcomes were further validated using molecular docking and in vitro experiments.

Results

The analysis of CHIKV targets using the Kyoto Encyclopedia of Genes and Genomes and MCODE identified IL-17 as an important pathogenic pathway in CHIKV infection. Among the 30 targets of ROSA against CHIKV, nearly half were found to be involved in the IL-17 signaling pathway. This suggests that ROSA may help the host in resisting CHIKV invasion by modulating this pathway. Molecular docking validation results showed that ROSA can stably bind to 10 core targets out of the 30 identified targets. In an in vitro CHIKV infection model developed using 293T cells, treatment with 60 μM ROSA significantly improved the survival rate of infected cells, inhibited 50% CHIKV proliferation after CHIKV infection, and reduced the expression of TNF-α in the IL-17 signaling pathway.

Conclusion

This study provides the first confirmation of the efficacy of ROSA in suppressing CHIKV infection through the IL-17 signaling pathway. The findings warrant further investigation to facilitate the development of ROSA as a potential treatment for CHIKV infection.

Risk of death following chikungunya virus disease in the 100 Million Brazilian Cohort, 2015-18: a matched cohort study and self-controlled case series

BACKGROUND

Chikungunya virus outbreaks have been associated with excess deaths at the ecological level. Previous studies have assessed the risk factors for severe versus mild chikungunya virus disease. However, the risk of death following chikungunya virus disease compared with the risk of death in individuals without the disease remains unexplored. We aimed to investigate the risk of death in the 2 years following chikungunya virus disease.

METHODS

We used a population-based cohort study and a self-controlled case series to estimate mortality risks associated with chikungunya virus disease between Jan 1, 2015, and Dec 31, 2018, in Brazil. The dataset was created by linking national databases for social programmes, notifiable diseases, and mortality. For the matched cohort design, individuals with chikungunya virus disease recorded between Jan 1, 2015, and Dec 31, 2018, were considered as exposed and those who were arbovirus disease-free and alive during the study period were considered as unexposed. For the self-controlled case series, we included all deaths from individuals with a chikungunya virus disease record, and each individual acted as their own control according to different study periods relative to the date of disease. The primary outcome was all-cause natural mortality up to 728 days after onset of chikungunya virus disease symptoms, and secondary outcomes were cause-specific deaths, including ischaemic heart diseases, diabetes, and cerebrovascular diseases.

FINDINGS

In the matched cohort study, we included 143 787 individuals with chikungunya virus disease who were matched, at the day of symptom onset, to unexposed individuals using sociodemographic factors. The incidence rate ratio (IRR) of death within 7 days of chikungunya symptom onset was 8·40 (95% CI 4·83-20·09) as compared with the unexposed group and decreased to 2·26 (1·50-3·77) at 57-84 days and 1·05 (0·82-1·35) at 85-168 days, with IRR close to 1 and wide CI in the subsequent periods. For the secondary outcomes, the IRR of deaths within 28 days after disease onset were: 1·80 (0·58-7·00) for cerebrovascular diseases, 3·75 (1·33-17·00) for diabetes, and 3·67 (1·25-14·00) for ischaemic heart disease, and there was no evidence of increased risk in the subsequent periods. For the self-controlled case series study, 1933 individuals died after having had chikungunya virus disease and were included in the analysis. The IRR of all-cause natural death within 7 days of symptom onset of chikungunya virus disease was 8·75 (7·18-10·66) and decreased to 1·59 (1·26-2·00) at 57-84 days and 1·09 (0·92-1·29) at 85-168 days. For the secondary outcomes, the IRRs of deaths within 28 days after disease onset were: 2·73 (1·50-4·96) for cerebrovascular diseases, 8·43 (5·00-14·21) for diabetes, and 2·38 (1·33-4·26) for ischaemic heart disease, and there was no evidence of increased risk at 85-168 days.

INTERPRETATION

Chikungunya virus disease is associated with an increased risk of death for up to 84 days after symptom onset, including deaths from cerebrovascular diseases, ischaemic heart diseases, and diabetes. This study highlights the need for equitable access to approved vaccines and effective anti-chikungunya virus therapeutics and reinforces the importance of robust vector-control efforts to reduce viral transmission.

FUNDING

Brazilian National Research Council (CNPq), Fundação de Amparo à Pesquisa do Estado da Bahia, Wellcome Trust, and UK Medical Research Council.

TRANSLATION

For the Portuguese translation of the abstract see Supplementary Materials section.

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.

The impact of arthritogenic viruses in oral tissues

Arthritis and periodontitis are inflammatory diseases that share several immunopathogenic features. The expansion in the study of virus-induced arthritis has shed light on how this condition could impact other parts of the human body, including the mouth. Viral arthritis is an inflammatory joint disease caused by several viruses, most notably the alphaviruses Chikungunya virus (CHIKV), Sindbis virus (SINV), Ross River virus (RRV), Mayaro virus (MAYV), and O'nyong'nyong virus (ONNV). These viruses can induce an upsurge of matrix metalloproteinases and immune-inflammatory mediators such as Interleukin-6 (IL6), IL-1β, tumor necrosis factor, chemokine ligand 2, and receptor activator of nuclear factor kappa-B ligand in the joint and serum of infected individuals. This can lead to the influx of inflammatory cells to the joints and associated muscles as well as osteoclast activation and differentiation, culminating in clinical signs of swelling, pain, and bone resorption. Moreover, several data indicate that these viral infections can affect other sites of the body, including the mouth. The human oral cavity is a rich and diverse microbial ecosystem, and viral infection can disrupt the balance of microbial species, causing local dysbiosis. Such events can result in oral mucosal damage and gingival bleeding, which are indicative of periodontitis. Additionally, infection by RRV, CHIKV, SINV, MAYV, or ONNV can trigger the formation of osteoclasts and upregulate pro-osteoclastogenic inflammatory mediators, interfering with osteoclast activation. As a result, these viruses may be linked to systemic conditions, including oral manifestations. Therefore, this review focuses on the involvement of alphavirus infections in joint and oral health, acting as potential agents associated with oral mucosal inflammation and alveolar bone loss. The findings of this review demonstrate how alphavirus infections could be linked to the comorbidity between arthritis and periodontitis and may provide a better understanding of potential therapeutic management for both conditions.

Design, synthesis, and lead optimization of piperazinyl-pyrimidine analogues as potent small molecules targeting the viral capping machinery of Chikungunya virus

The worldwide re-emerge of the Chikungunya virus (CHIKV), the high morbidity associated with it, and the lack of an available vaccine or antiviral treatment make the development of a potent CHIKV-inhibitor highly desirable. Therefore, an extensive lead optimization was performed based on the previously reported CHVB compound 1b and the reported synthesis route was optimized - improving the overall yield in remarkably shorter synthesis and work-up time. Hundred analogues were designed, synthesized, and investigated for their antiviral activity, physiochemistry, and toxicological profile. An extensive structure-activity relationship study (SAR) was performed, which focused mainly on the combination of scaffold changes and revealed the key chemical features for potent anti-CHIKV inhibition. Further, a thorough ADMET investigation of the compounds was carried out: the compounds were screened for their aqueous solubility, lipophilicity, their toxicity in CaCo-2 cells, and possible hERG channel interactions. Additionally, 55 analogues were assessed for their metabolic stability in human liver microsomes (HLMs), leading to a structure-metabolism relationship study (SMR). The compounds showed an excellent safety profile, favourable physicochemical characteristics, and the required metabolic stability. A cross-resistance study confirmed the viral capping machinery (nsP1) to be the viral target of these compounds. This study identified 31b and 34 as potent, safe, and stable lead compounds for further development as selective CHIKV inhibitors. Finally, the collected insight led to a successful scaffold hop (64b) for future antiviral research studies.

IgM-specific linear epitopes on the E2 protein for serodiagnosis of Chikungunya

Chikungunya virus (CHIKV) and Dengue virus (DENV) are vector-borne diseases transmitted by Aedes aegypti and Aedes albopictus that pose a significant threat to global public health. Cases of acute Chikungunya fever often present similar clinical symptoms to other vector-borne diseases, such as Dengue fever. In regions where multiple vector-borne diseases coexist, CHIKV is often overlooked or misdiagnosed as Dengue virus, West Nile virus, Zika virus or other viral infections, which delays its prevention and control. However, IgM antibodies directed against the E2 protein of CHIKV have not yet been generalized to clinical settings due to the low sensitivity and high cost in commercial kits. Indirect ELISA with peptides provides an effective supplementary tool for detecting CHIKV IgM antibodies. Our study aims at examining the potential of linear epitopes on the E2 glycoprotein that specifically bind to IgM antibodies as serodiagnostic tool for CHIKV. The sensitivity of the established peptide indirect ELISA method for detecting clinical samples is significantly better than that of commercial kits, realizing a beneficial supplement to the existing IgM antibody assay. It also established the groundwork for comprehending the biological mechanisms of the CHIKV E2 protein and the advancement of innovative epitope peptide vaccines.

Emerging and re-emerging pediatric viral diseases: a continuing global challenge

The twenty-first century has been marked by a surge in viral epidemics and pandemics, highlighting the global health challenge posed by emerging and re-emerging pediatric viral diseases. This review article explores the complex dynamics contributing to this challenge, including climate change, globalization, socio-economic interconnectedness, geopolitical tensions, vaccine hesitancy, misinformation, and disparities in access to healthcare resources. Understanding the interactions between the environment, socioeconomics, and health is crucial for effectively addressing current and future outbreaks. This scoping review focuses on emerging and re-emerging viral infectious diseases, with an emphasis on pediatric vulnerability. It highlights the urgent need for prevention, preparedness, and response efforts, particularly in resource-limited communities disproportionately affected by climate change and spillover events. Adopting a One Health/Planetary Health approach, which integrates human, animal, and ecosystem health, can enhance equity and resilience in global communities. IMPACT: We provide a scoping review of emerging and re-emerging viral threats to global pediatric populations This review provides an update on current pediatric viral threats in the context of the COVID-19 pandemic This review aims to sensitize clinicians, epidemiologists, public health practitioners, and policy stakeholders/decision-makers to the role these viral diseases have in persistent pediatric morbidity and mortality.

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 role of Niemann-pick C1 (NPC1) in viral infections and inhibition of viral infections through NPC1 inhibitor

Viruses communicate with their hosts through interactions with proteins, lipids, and carbohydrate moieties on the plasma membrane (PM), often resulting in viral absorption via receptor-mediated endocytosis. Many viruses cannot multiply unless the host's cholesterol level remains steady. The large endo/lysosomal membrane protein (MP) Niemann-Pick C1 (NPC1), which is involved in cellular cholesterol transport, is a crucial intracellular receptor for viral infection. NPC1 is a ubiquitous housekeeping protein essential for the controlled cholesterol efflux from lysosomes. Its human absence results in Niemann-Pick type C disease, a deadly lysosomal storage disorder. NPC1 is a crucial viral receptor and an essential host component for filovirus entrance, infection, and pathogenesis. For filovirus entrance, NPC1's cellular function is unnecessary. Furthermore, blocking NPC1 limits the entry and replication of the African swine fever virus by disrupting cholesterol homeostasis. Cell entrance of quasi-enveloped variants of hepatitis A virus and hepatitis E virus has also been linked to NPC1. By controlling cholesterol levels, NPC1 is also necessary for the effective release of reovirus cores into the cytoplasm. Drugs that limit NPC1's activity are effective against several viruses, including SARS-CoV and Type I Feline Coronavirus (F-CoV). These findings reveal NPC1 as a potential therapeutic target for treating viral illnesses and demonstrate its significance for several viral infections. This article provides a synopsis of NPC1's function in viral infections and a review of NPC1 inhibitors that may be used to counteract viral infections. Video Abstract.

Chikungunya virus perturbs the Wnt/β-catenin signaling pathway for efficient viral infection

IMPORTANCE

Being obligate parasites, viruses use various host cell machineries in effectively replicating their genome, along with virus-encoded enzymes. In order to carry out infection and pathogenesis, viruses are known to manipulate fundamental cellular processes in cells and interfere with host gene expression. Several viruses interact with the cellular proteins involved in the Wnt/β-catenin pathway; however, reports regarding the involvement of protein components of the Wnt/β-catenin pathway in Chikungunya virus (CHIKV) infection are scarce. Additionally, there are currently no remedies or vaccines available for CHIKV. This is the first study to report that modulation of the Wnt/β-catenin pathway is crucial for effective CHIKV infection. These investigations deepen the understanding of the underlying mechanisms of CHIKV infection and offer new avenue for developing effective countermeasures to efficiently manage CHIKV infection.

Flying under the radar - impact and factors influencing asymptomatic DENV infections

The clinical outcome of DENV and other Flaviviruses infections represents a spectrum of severity that ranges from mild manifestations to severe disease, which can ultimately lead to death. Nonetheless, most of these infections result in an asymptomatic outcome that may play an important role in the persistent circulation of these viruses. Also, although little is known about the mechanisms that lead to these asymptomatic infections, they are likely the result of a complex interplay between viral and host factors. Specific characteristics of the infecting viral strain, such as its replicating efficiency, coupled with host factors, like gene expression of key molecules involved in the immune response or in the protection against disease, are among crucial factors to study. This review revisits recent data on factors that may contribute to the asymptomatic outcome of the world's widespread DENV, highlighting the importance of silent infections in the transmission of this pathogen and the immune status of the host.

Impact of the microbiome on mosquito-borne diseases

Mosquito-borne diseases present a significant threat to human health, with the possibility of outbreaks of new mosquito-borne diseases always looming. Unfortunately, current measures to combat these diseases such as vaccines and drugs are often either unavailable or ineffective. However, recent studies on microbiomes may reveal promising strategies to fight these diseases. In this review, we examine recent advances in our understanding of the effects of both the mosquito and vertebrate microbiomes on mosquito-borne diseases. We argue that the mosquito microbiome can have direct and indirect impacts on the transmission of these diseases, with mosquito symbiotic microorganisms, particularly Wolbachia bacteria, showing potential for controlling mosquito-borne diseases. Moreover, the skin microbiome of vertebrates plays a significant role in mosquito preferences, while the gut microbiome has an impact on the progression of mosquito-borne diseases in humans. As researchers continue to explore the role of microbiomes in mosquito-borne diseases, we highlight some promising future directions for this field. Ultimately, a better understanding of the interplay between mosquitoes, their hosts, pathogens, and the microbiomes of mosquitoes and hosts may hold the key to preventing and controlling mosquito-borne diseases.

Influence of host genetic polymorphisms involved in immune response and their role in the development of Chikungunya disease: a review

Chikungunya virus (CHIKV) is transmitted by the bite of infected mosquitoes and can cause significant pathogenicity in humans. Moreover, its importance has increased in the Americas since 2013. The primary vectors for viral delivery are the mosquito species Aedes aegypti and Aedes albopictus. Several factors, including host genetic variations and immune response against CHIKV, influence the outcomes of Chikungunya disease. This work aimed to gather information about different single nucleotide polymorphisms (SNPs) in genes that influence the host immune response during an infection by CHIKV. The viral characteristics, disease epidemiology, clinical manifestations, and immune response against CHIKV are also addressed. The main immune molecules related to this arboviral disease elucidated in this review are TLR3/7/8, DC-SIGN, HLA-DRB1/HLA-DQB1, TNF, IL1RN, OAS2/3, and CRP. Advances in knowledge about the genetic basis of the immune response during CHIKV infection are essential for expanding the understanding of disease pathophysiology, providing new genetic markers for prognosis, and identifying molecular targets for the development of new drug treatments.

Epidemiology and Transmission Dynamics of Viral Encephalitides in West Africa

Encephalitis is an inflammation of the brain, often caused by an autoimmune reaction, or in most cases because of a direct viral, bacterial, or parasitic infection. Viral encephalitides (VE) presents a significant public health concern globally, especially in West Africa. There are more than five hundred known arthropod-borne viruses (arboviruses), with over a hundred of them identified to cause encephalitic diseases in humans and animals, giving rise to a tremendous burden of the diseases and socioeconomic strains in tropical and subtropical regions worldwide. Despite their importance, few effective preventive and control measures in the form of vaccines and therapies are available, and when they are, their use is limited. These limitations are largely hinged on the paucity of information about the molecular epidemiology and transmission patterns of VE in West Africa. Here, we reviewed the transmission dynamics, molecular epidemiology, and the ecological drivers of VE in West Africa. Collectively, timely and accurate interventions are essential for encephalitic viral disease control. Moreover, the integrated health system approach, combining surveillance, vaccination, vector control, and community engagement, could be effective in preventing viral encephalitis globally.

Seroprevalence of Alphaviruses (Togaviridae) among Urban Population in Nouakchott, Mauritania, West Africa

The presence of alphaviruses, such as chikungunya virus (CHIKV), has never been reported in Mauritania. We assessed the seroprevalence of CHIKV among Nouakchott residents. A cross-sectional study involving 1300 non-febrile patients consulting at the Nouakchott hospital center was conducted between January and June 2021. The presence of anti-CHIKV IgG and neutralizing antibodies against CHIKV, O'nyong-nyong virus (ONNV), and Semliki Forest virus (SFV) was determined by an enzyme-linked immunosorbent assay (ELISA) and a serum neutralization test, respectively, and the associated risk factors were investigated. Of the 1300 study participants, serological evidence of previous exposure to CHIKV was observed in 37 individuals (2.8%). Sex, age, reported use of repellants, and bed net ownership and usage were not associated with CHIKV seropositivity. Our results showed the co-circulation of two other alphaviruses, ONNV and SFV, in Nouakchott in 30 (2.3%) individuals. This is the first study that documents the co-circulation of CHIKV, ONNV, and SFV in Mauritania, albeit at low prevalence. Surveillance and routine testing for alphaviruses and other arboviruses in symptomatic patients should be implemented in health facilities to assess the health burden associated with these viruses. Efforts should also be made to strengthen the vector control measures.

Emerging and re-emerging zoonotic viral diseases in Southeast Asia: One Health challenge

The ongoing significant social, environmental, and economic changes in Southeast Asia (SEA) make the region highly vulnerable to the emergence and re-emergence of zoonotic viral diseases. In the last century, SEA has faced major viral outbreaks with great health and economic impact, including Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), arboviruses, highly pathogenic avian influenza (H5N1), and Severe Acute Respiratory Syndrome (SARS-CoV); and so far, imported cases of Middle East Respiratory Syndrome Coronavirus (MERS-CoV). Given the recent challenging experiences in addressing emerging zoonotic diseases, it is necessary to redouble efforts to effectively implement the "One Health" initiative in the region, which aims to strengthen the human-animal-plant-environment interface to better prevent, detect and respond to health threats while promoting sustainable development. This review provides an overview of important emerging and re-emerging zoonotic viral diseases in SEA, with emphasis on the main drivers behind their emergency, the epidemiological situation from January 2000 to October 2022, and the importance of One Health to promote improved intervention strategies.

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: risks for travellers

RATIONALE FOR REVIEW

Chikungunya outbreaks continue to occur, with changing epidemiology. Awareness about chikungunya is low both among the at-risk travellers and healthcare professionals, which can result in underdiagnosis and underreporting. This review aims to improve awareness among healthcare professionals regarding the risks of chikungunya for travellers.

KEY FINDINGS

Chikungunya virus transmission to humans occurs mainly via daytime-active mosquitoes, Aedes aegypti and Aedes albopictus. The areas where these mosquitoes live is continuously expanding, partly due to climate changes. Chikungunya is characterized by an acute onset of fever with joint pain. These symptoms generally resolve within 1-3 weeks, but at least one-third of the patients suffer from debilitating rheumatologic symptoms for months to years. Large outbreaks in changing regions of the world since the turn of the 21st century (e.g. Caribbean, La Réunion; currently Brazil, India) have resulted in growing numbers of travellers importing chikungunya, mainly to Europe and North America. Viremic travellers with chikungunya infection have seeded chikungunya clusters (France, United States of America) and outbreaks (Italy in 2007 and 2017) in non-endemic countries where Ae. albopictus mosquitoes are present. Community preventive measures are important to prevent disease transmission by mosquitoes. Individual preventive options are limited to personal protection measures against mosquito bites, particularly the daytime-active mosquitos that transmit the chikungunya virus. Candidate vaccines are on the horizon and regulatory authorities will need to assess environmental and host risk factors for persistent sequelae, such as obesity, age (over 40 years) and history of arthritis or inflammatory rheumatologic disease to determine which populations should be targeted for these chikungunya vaccines.

CONCLUSIONS/RECOMMENDATIONS

Travellers planning to visit destinations with active CHIKV circulation should be advised about the risk for chikungunya, prevention strategies, the disease manifestations, possible chronic rheumatologic sequelae and, if symptomatic, seek medical evaluation and report potential exposures.

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.

Chikungunya Virus Vaccine Candidate Incorporating Synergistic Mutations Is Attenuated and Protects Against Virulent Virus Challenge

BACKGROUND

Chikungunya virus (CHIKV) is an arbovirus that periodically emerges to cause large epidemics of arthritic disease. Although the robust immunity elicited by live-attenuated virus (LAV) vaccine candidates makes them attractive, CHIKV vaccine development has been hampered by a high threshold for acceptable adverse events.

METHODS

We evaluated the vaccine potential of a recently described LAV, skeletal muscle-restricted virus (SKE), that exhibits diminished replication in skeletal muscle due to insertion of target sequences for skeletal muscle-specific miR-206. We also evaluated whether these target sequences could augment safety of an LAV encoding a known attenuating mutation, E2 G82R. Attenuation of viruses containing these mutations was compared with a double mutant, SKE G82R.

RESULTS

SKE was attenuated in both immunodeficient and immunocompetent mice and induced a robust neutralizing antibody response, indicating its vaccine potential. However, only SKE G82R elicited diminished swelling in immunocompetent mice at early time points postinoculation, indicating that these mutations synergistically enhance safety of the vaccine candidate.

CONCLUSIONS

These data suggest that restriction of LAV replication in skeletal muscle enhances tolerability of reactogenic vaccine candidates and may improve the rational design of CHIKV vaccines.

Factors Affecting Arbovirus Midgut Escape in Mosquitoes

Arboviral diseases spread by mosquitoes cause significant morbidity and mortality throughout much of the world. The treatment and prevention of these diseases through medication and vaccination is often limited, which makes controlling arboviruses at the level of the vector ideal. One way to prevent the spread of an arbovirus would be to stop its vector from developing a disseminated infection, which is required for the virus to make its way to the saliva of the mosquito to be potentially transmitted to a new host. The midgut of the mosquito provides one such opportunity to stop an arbovirus in its tracks. It has been known for many years that in certain arbovirus-vector combinations, or under certain circumstances, an arbovirus can infect and replicate in the midgut but is unable to escape from the tissue to cause disseminated infection. This situation is known as a midgut escape barrier. If we better understand why this barrier occurs, it might aid in the development of more informed control strategies. In this review, we discuss how the midgut escape barrier contributes to virus-vector specificity and possible mechanisms that may allow this barrier to be overcome in successful virus-vector combinations. We also discuss several of the known factors that either increase or decrease the likelihood of midgut escape.

Prevalence of Barmah Forest Virus, Chikungunya Virus and Ross River Virus Antibodies among Papua New Guinea Military Personnel before 2019

Barmah Forest virus (BFV), Chikungunya virus (CHIKV) and Ross River virus (RRV) belong to the Alphavirus genus of the family Togaviridae. All three virus infections have been reported in Papua New Guinea (PNG) previously, but the exact prevalence and distribution of these three alphaviruses in PNG has not been established. Sera collected from 204 PNG Military Personnel (PNGMP) study participants in April 2019 was tested for the presence of anti-BFV, anti-CHIKV and anti-RRV immunoglobulin G (IgG) antibodies using commercially available enzyme-linked immunosorbent assay (ELISA) IgG detection kits, as well as for specific neutralizing antibodies (NAb) against individual viruses. Overall, sero-positivity of the sera was anti-BFV IgG 12.3% (25/204), anti-BFV NAb 8.3% (17/204); anti-CHIKV IgG 47.1% (96/204), anti-CHIKV NAb 34.8% (71/204); and anti-RRV IgG 93.1% (190/204), anti-RRV NAb 56.4% (115/204), respectively. Of the 137/204 participants that were Nab-positive for at least one virus, we identified 4 BFV, 40 CHIKV and 73 RRV single infections, and 9 RRV+CHIKV and 11 BFV+RRV double infections. The lower proportion of NAb sero-positive compared to the ELISA IgG sero-positive assay samples suggests that the currently available commercial ELISA detection kits for these three alphaviruses may not be suitable for diagnostic/surveillance purposes in endemic areas such as PNG, due to serological cross-reactivity among these three alphaviruses. Laboratory testing using known positive control sera indicated no cross-neutralization between BFV and RRV; however, some RRV or BFV single infection human sera demonstrated low-level cross-neutralization against CHIKV (the ratio of RRV/CHIKV NAb titers or BFV/CHIKV ≥ 4). Our preliminary results indicate that the majority of PNGMP have previously been exposed to RRV, with mild exposure to CHIKV and low-level exposure to BFV, suggesting that multiple alphaviruses have been circulating among PNGMP. The transmission landscapes of these three alphaviruses across PNG should be prioritized for further investigation, including identification of specific vectors and hosts that mediate human spillover in order to mitigate future outbreaks. Ongoing education regarding precautionary and protective measures are needed to better protect individuals who travel to PNG.

Imidazonaphthyridine effects on Chikungunya virus replication: Antiviral activity by dependent and independent of interferon type 1 pathways

The Chikungunya virus (CHIKV) causes Chikungunya fever, a disease characterized by symptoms such as arthralgia/polyarthralgia. Currently, there are no antivirals approved against CHIKV, emphasizing the need to develop novel therapies. The imidazonaphthyridine compound (RO8191), an interferon-α (IFN-α) agonist, was reported as a potent inhibitor of HCV. Here RO8191 was investigated for its potential to inhibit CHIKV replication in vitro. RO8191 inhibited CHIKV infection in BHK-21 and Vero-E6 cells with a selectivity index (SI) of 12.3 and 37.3, respectively. Additionally, RO8191 was capable to protect cells against CHIKV infection, inhibit entry by virucidal activity, and strongly impair post-entry steps of viral replication. An effect of RO8191 on CHIKV replication was demonstrated in BHK-21 through type-1 IFN production mechanism and in Vero-E6 cells which has a defective type-1 IFN production, also suggesting a type-1 IFN independent mode of action. Molecular docking calculations demonstrated interactions of RO8191 with the CHIKV E proteins, corroborated by the ATR-FTIR assay, and with non-structural proteins, supported by the CHIKV-subgenomic replicon cells assay.

Pathogenesis of chronic chikungunya arthritis: Resemblances and links with rheumatoid arthritis

Chikungunya virus (CHIKV) infection results from transmission by the mosquito vector. Following an incubation period of 5-7 days, patients develop an acute febrile illness, chikungunya fever (CHIKF), characterized by high fevers, maculopapular rash, headaches, polyarthritis/arthralgias, myalgias, nausea, vomiting, and diarrhea. Joint pain is often severe, and most often involves the hands, the wrists, the ankles, and the metatarsal-phalangeal joints of the feet. Many patients recover within several weeks, but up to 50% develop chronic joint pain and swelling for more than 12 weeks, then we refer to these symptoms as chronic chikungunya arthritis (CCA). The pathogenesis of CCA is not well understood. In this article, we suggest that mesenchymal stem cells (MSCs) may play an important role in this pathogenesis. This heterogeneous group of multipotent cells, morphologically similar to fibroblasts, may undergo epigenetic changes capable of generating aberrant progenies. However, we believe that there is no need for a latent infection. In our pathogenic hypothesis, CHIKV infection of MSCs would cause epigenetic changes both in MSCs themselves and in their progenies, without the need for reactivation of dormant viruses.

Hydrothermal Synthesis of Multifunctional Bimetallic Ag-CuO Nanohybrids and Their Antimicrobial, Antibiofilm and Antiproliferative Potential

The rapidly growing global problem of infectious pathogens acquiring resistance to conventional antibiotics is an instigating reason for researchers to continue the search for functional as well as broad-spectrum antimicrobials. Hence, we aimed in this study to synthesis silver-copper oxide (Ag-CuO) nanohybrids as a function of Ag concentration (0.05, 0.1, 0.3 and 0.5 g) via the one-step hydrothermal method. The bimetallic Ag-CuO nanohybrids Ag-C-1, Ag-C-2, Ag-C-3 and Ag-C-4 were characterized for their physico-chemical properties. The SEM results showed pleomorphic Ag-CuO crystals; however, the majority of the particles were found in spherical shape. TEM results showed that the Ag-CuO nanohybrids in formulations Ag-C-1 and Ag-C-3 were in the size range of 20-35 nm. Strong signals of Ag, Cu and O in the EDX spectra revealed that the as-synthesized nanostructures are bimetallic Ag-CuO nanohybrids. The obtained Ag-C-1, Ag-C-2, Ag-C-3 and Ag-C-4 nanohybrids have shown their MICs and MBCs against E. coli and C. albicans in the range of 4-12 mg/mL and 2-24 mg/mL, respectively. Furthermore, dose-dependent toxicity and apoptosis process stimulation in the cultured human colon cancer HCT-116 cells have proven the Ag-CuO nanohybrids as promising antiproliferative agents against mammalian cancer.