Diagnostic Options and Challenges for Dengue and Chikungunya Viruses

Identification of Immunodominant Epitopes of Dengue Virus 2 Envelope and NS1 Proteins: Evaluating the Diagnostic Potential of a Synthetic Peptide

BACKGROUND AND OBJECTIVE

Dengue is a major infectious disease with potential for outbreaks and epidemics. A specific and sensitive diagnosis is a prerequisite for clinical management of the disease. We designed our study to identify epitopes on the Dengue virus (DENV) envelope (E) and non-structural protein 1 (NS1) with potential for diagnosis.

METHODS

Serology and immunoinformatic approaches were employed. We collected DENV-positive, DENV-negative and Japanese encephalitis virus-positive samples from collaborating hospitals in 2019 and 2022-2023. Seropositive peptides in 15-18 mer peptide arrays of E and NS1 proteins of DENV2 were determined by an indirect enzyme-linked immunosorbent assay. B-cell linear and conformational epitopes were predicted using BepiPred2.0 and ElliPro, respectively. A consensus recombinant peptide was designed, synthesised and evaluated for its diagnostic potential using patient sera.

RESULTS

Eight peptides of E protein and six peptides of NS1 protein were identified to be the most frequently recognised by Dengue-positive patients. These peptide sequences were compared with B-cell epitope regions and found to be overlapped with predicted B-cell linear and conformational epitopes. EP11 and NSP15 showed a 100% amino acid sequence overlap with B-cell epitopes. EP1 and NSP15 had 14 whereas EP28, EP31, EP60 16, NSP12 and NSP32 had more than 15 interacting interface residues with a neutralising antibody, suggesting a strength of interaction. Interestingly, potential epitopes identified were localised on the surface of proteins as visualised by PyMOL. Validation with a recombined synthetic peptide yielded 92.3% sensitivity and 91.42% specificity.

CONCLUSIONS

Immunodominant regions identified by serology and computationally predicted epitopes overlapped, thereby showing the robustness of the methodology and the peptide designed for diagnosis.

Molecular identification and phylogenetic analysis of chikungunya virus among dengue-negative patients in Kolkata, India

Dengue and chikungunya are co-circulating vector-borne diseases that share a significant number of clinical symptoms. To identify variables to aid physicians in making rapid and effective diagnostic decisions, we performed molecular diagnosis of the chikungunya virus and examined the clinical manifestations of chikungunya cases to identify the prevalence among dengue-negative individuals in Kolkata. Dengue suspected patients' samples were collected during January 2020-December 2021 and Enzyme-linked immunosorbent assay (ELISA) and reverse transcription-polymerase chain reaction (RT-PCR) methods have been performed to confirm the prevalence of chikungunya infection among dengue-negative patients. By performing phylogenetic analysis, comparing clinical classifications, identifying disease aetiology using clinical and laboratory factors, and evaluating the time course of several clinical variables, we have evaluated the clinical manifestations linked to dengue and chikungunya virus infections. Chikungunya infection was found in 15.1% and 6.3% of the 635 dengue-negative patients, as determined by ELISA and RT-PCR, respectively. Arthritis and myalgia were more common in chikungunya-infected patients at the time of hospital admission while conjunctivitis, photosensitivity, arthralgia, Anorexia, fatigue, retro-orbital pain, vomiting, dermatitis, or swollen glands were significantly presented as an overlapping symptom. Although dengue and chikungunya infections have significant clinical overlap, basic clinical and laboratory criteria can predict these diseases at presentation for proper management. Effective management enables doctors to treat and care for patients properly and contributes to the development of control measures for these infections in a medical setting.

Recent Advances in the Role of Different Nanoparticles in the Various Biosensors for the Detection of the Chikungunya Virus

Humans contract the Chikungunya virus (CHIKV), an alphavirus transmitted by mosquitoes that induces acute and chronic musculoskeletal discomfort and fever. Millions of cases of the disease have been attributed to CHIKV in the Indian Ocean region since 2004, and the virus has since spread to Europe, the Middle East, and the Pacific. The exponential proliferation of CHIKV in recent times underscores the critical nature of implementing preventative measures and exploring potential control strategies. The principal laboratory test employed to diagnose infection in serum samples collected over six days after the onset of symptoms is the detection of CHIKV or viral RNA. Although two commercially available real-time reverse transcription-polymerase chain reaction products exist, data on their validity are limited. A diagnostic instrument that is rapid, sensitive, specific, and cost-effective is, therefore an absolute necessity, particularly in developing nations. Biosensors have demonstrated considerable potential in the realm of pathogen detection. The rapid and sensitive detection of viruses has been facilitated by the development of numerous types of biosensors, including affinity-based nano-biosensors, graphene affinity-based biosensors, optical nano-biosensors, surface Plasmon Resonance-based optical nano-biosensors, and electrochemical nano-biosensors. Furthermore, the utilization of nanomaterials for signal extension, including but not limited to gold and silver nanoparticles, quantum dots, and iron oxide NPs, has enhanced the precision and sensitivity of biosensors. The developed innovative diagnostic method is time-efficient, precise, and economical; it can be implemented as a point-of-care device. The technique may be implemented in diagnostic laboratories and hospitals to identify patients infected with CHIKV. Throughout this article, we have examined a multitude of CHIKV nano-biosensors and their respective properties. Following a discussion of representative nanotechnologies for biosensors, numerous NPs-assisted CHIKV nano-biosensors are summarized in this article. As a result, we anticipate that this review will furnish a significant foundation for advancing innovative CHIKV nano-biosensors.

The Chikungunya virus: A reemerging cause of acute febrile illness in the high jungle of northern Peru

BACKGROUND

The Chikungunya virus (CHIKV) is an emerging arthropod-borne virus (arbovirus) that causes undifferentiated acute febrile illness. Cases of CHIKV may be under-reported in Peru, given the various difficulties in diagnosing it, such as lack of diagnostic tests in remote areas, the passive nature of epidemiological surveillance, and co-circulation of other arthropod-borne pathogens. Therefore, a study was conducted in the high jungle of northern Peru to determine the prevalence of CHIKV among febrile patients and describe their clinical characteristics.

METHODS

A cross-sectional study was conducted in the province of Jaen, Cajamarca, located in the high jungle of northern Peru. Patients attending primary healthcare centers within Cajamarca's Regional Health Directorate were enrolled. The study took place from June 2020 through June 2021. Patients were eligible if they sought outpatient healthcare for a clinical diagnosis of acute febrile illness (AFI). Serum samples were collected from all patients, and the diagnosis of CHIKV was determined using real-time RT-PCR, as well as the detection of IgM antibodies by ELISA. A logistic regression model was employed to identify the risk factors for CHIKV, and the odds ratios (ORs) were calculated, along with their corresponding 95% confidence intervals (95% CI).

RESULTS

A total of 1 047 patients with AFI were included during the study period. CHIKV was identified in 130 patients of 1 047 (12.4%). Among the CHIKV positive cases, 84 of 130 (64.6%) were diagnosed by RT-PCR, 42 of 130 (32.3%) by IgM ELISA detection, and 4 of 130 (3.1%) by both assays. The majority of patients with CHIKV infection fell within the 18-39 years age group (50.0%), followed by the 40-59 years age group (23.9%) and those with 60 years or older (10.8%). The most common clinical symptoms observed in patients with CHIKV infection were headache (85.4%), myalgias (72.3%), and arthralgias (64.6%). The highest number of positive CHIKV cases occurred in May (23.1%), followed by March (20.0%) and February (13.8%) of 2021.

CONCLUSION

The study reports a considerable frequency of CHIKV infections among patients with AFI from the high jungle of northern Peru. These findings highlight the importance of recognizing CHIKV as an ongoing pathogen with continuous transmission in various areas of Peru. It is crucial to enhance epidemiological surveillance by implementing reliable diagnostic techniques, as the clinical symptoms of CHIKV infection can be nonspecific.

Simultaneous detection and differentiation of dengue and chikungunya viruses for commercial utility

The diagnosis of Dengue and Chikungunya infections during acute phase is a priority considering emerging pattern and increasing trends of their infections. The present study describes the commercial development and validation of RT-PCR test for the simultaneous detection of of DEN and CHIK viral RNA in a single tube from human plasma samples. Multistep one step RT-PCR assay was developed and validated for detection and discrimination of DEN and CHIK along with exogenous internal control. The test was evaluated for commercial use using 3 different lots to determine analytical sensitivity, specificity, precision and stability. The external clinical evaluation was performed at NABL accredited lab with known positive and negative Chikungunya and Dengue specimens and comparator assay method. The findings showed that the test could identify CHIK and DEN viral nucleic acid in clinical samples within 80 min, without any cross-reactivity. The analytical detection limit of the test was 1.56 copies/µl for both. The clinical sensitivity and specificity was ≥ 98% and provide a high-throughput and screen up to 90 samples in a single run. It is available in a freeze-dried format and can be used in both the manual and automated platforms. This unique combo test, PathoDetect™ "CHIK DEN Multiplex PCR Kit" enables simultaneous, sensitive, specific detection of DENV and CHIKV and serves as "ready to use" platform for commercial use. It would aid the differential diagnosis as early as day 1 of the infection and facilitate screen-and-treat approach.

Improving dengue diagnosis and case confirmation in children by combining rapid diagnostic tests, clinical, and laboratory variables

Background

Dengue is the most widely distributed arboviral disease in tropical and subtropical countries. Most suspected cases are diagnosed according to the clinical criteria, and early diagnosis is difficult. Moreover, in underdeveloped countries, several factors continue to challenge the diagnosis and surveillance of dengue cases. This study aimed to design a diagnostic algorithm using rapid diagnostic tests (RDTs), ELISA tests, and clinical and hematological variables to confirm dengue cases in febrile patients in Colombia.

Methods

Altogether, 505 samples were collected. Serum samples were evaluated by RDTs (IgM and IgG antibodies and NS1 antigen), capture IgM and IgG ELISAs, and endpoint hemi-nested RT-PCR assay (qualitative). We statistically analyzed the performance of individual tests to determine the most useful ones to confirm dengue cases accurately.

Results

Individual results for IgM, IgG, and NS1 RDTs yielded lower sensitivity and specificity values than the reference standard. High sensitivity and specificity were obtained after combining IgM and NS1 ELISA results (96.3% and 96.4%) and NS1 RDT plus IgM ELISA results (90.3% and 96.2%), respectively. Adjusted odds ratios (aORs) were calculated for clinical variables and laboratory tests to differentiate dengue from other febrile illnesses (OFI). This approach showed that myalgia, abdominal tenderness, and platelet count were identified with higher sensitivity to confirm dengue cases. IgM RDT and NS1 RDT differentiated dengue cases from OFI. A positive IgM RDT or a positive NS1 RDT combined with specific signs or symptoms confirmed 81.6% of dengue cases. A combination of clinical findings and a positive NS1 RDT or positive ELISA IgM confirmed 90.6% of the cases.

Conclusion

Our findings showed that clinical diagnoses in pediatric population alone cannot confirm true dengue cases and needs to be complemented by laboratory diagnostic tests. We also demonstrate the usefulness of combining clinical criteria with RDTs, suggesting that their implementation with the IgM ELISA test improves dengue case confirmation.

Dengue-chikungunya infection in the tertiary care hospital of northern India: Cross-sectional latent class cluster analysis in viral infection

Cases of dengue and chikungunya fever are escalating all over India. Both viruses share a common vector, the "Aedes" mosquito. Due to similar clinical symptoms, both the dengue (DENV) and chikungunya (CHIKV) virus can circulate as co-infection. There is very limited data available on dengue-chikungunya co-infection in Uttarakhand, India. The purpose of this study was to determine the seroprevalence of dengue and chikungunya virus infections, as well as their co-infection, in patients presenting with clinical symptoms. Serum samples of clinically suspected patients from the tertiary care hospital of Uttarakhand were collected, and Latent Class Cluster Analysis was performed for clinical profiling. ELISA was performed for DENV and CHIKV. 279 cases were enrolled, out of which 222 (79.5%) came positive for dengue NS1 Ag, 143 (51.2%) for dengue IgM, 98 (35.1%) for IgG followed by 16 (5.7%) of CHIKV IgM, and 4 (1.4%) were NS1 Ag with CHIKV IgM. Among the clinical features, fever (n = 270, 96.8%) was the most common symptom in all suspected dengue and chikungunya cases. Other symptoms like chills (n = 254, 91.0%), arthralgia (n = 241, 86.4%), and headache (n = 240, 86.0%) were present in a significant number. Results showed fewer odds of getting both DENV and CHIKV infection simultaneously, but the risk is still not negligible. This study explores the clinical presentation of the suspected dengue-chikungunya case. The increasing incidence of dengue and chikungunya and their co-infection necessitate the authorities' active surveillance of endemic regions and effective patient care management.

Surface decorated reporter-tagged chikungunya virus-like particles for clinical diagnostics and identification of virus entry inhibitors

The ever-evolving and versatile VLP technology is becoming an increasingly popular area of science. This study presents surface decorated reporter-tagged VLPs of CHIKV, an enveloped RNA virus of the genus alphavirus and its applications. Western blot, IFA and live-cell imaging confirm the expression of reporter-tagged CHIK-VLPs from transfected HEK293Ts. CryoEM micrographs reveal particle diameter as ∼67nm and 56-70 nm, respectively, for NLuc CHIK-VLPs and mCherry CHIK-VLPs. Our study demonstrates that by exploiting NLuc CHIK-VLPs as a detector probe, robust ratiometric luminescence signal in CHIKV-positive sera compared to healthy controls can be achieved swiftly. Moreover, the potential activity of the Suramin drug as a CHIKV entry inhibitor has been validated through the reporter-tagged CHIK-VLPs. The results reported in this study open new avenues in the eVLPs domain and offer potential for large-scale screening of clinical samples and antiviral agents targeting entry of CHIKV and other alphaviruses.

Clinical and epidemiologic evaluation of a 2020 chikungunya outbreak in Cambodia

BACKGROUND

In 2020, the Kingdom of Cambodia experienced a nationwide outbreak of chikungunya virus (CHIKV). Despite an increase in the frequency of outbreaks and expanding geographic range of CHIKV, diagnostic challenges remain, and limited surveillance data of sufficient granularity are available to characterize epidemiological profiles and disease dynamics of the virus.

METHODS

An ongoing and long-standing cross-sectional study of acute undifferentiated febrile illness (AUFI) in Cambodia was leveraged to describe the disease epidemiology and characterize the clinical presentation of patients diagnosed with CHIKV during the 2020 outbreak. Participants presenting with AUFI symptoms at ten study locations provided acute and convalescent blood samples and were tested for CHIKV using a reverse transcription-polymerase chain reaction (RT-PCR) and serological diagnostic methods including IgM and IgG. Acute and follow-up clinical data were also collected.

RESULTS

From 1194 participant blood samples tested, 331 (27.7%) positive CHIKV cases were detected. Most CHIKV positive individuals (280, 84.6%) reported having a fever 3 to 4 days prior to visiting a health facility. Symptoms including chills, joint pain, nausea, vomiting, and lesions were all statistically significant among CHIKV positive participants compared to CHIKV negative AUFI participants. Cough was negatively associated with CHIKV positive participants. Positivity proportions were significantly higher among adults compared to children. No significant difference was found in positivity proportion between rainy and dry seasons during the outbreak. Positive CHIKV cases were detected in all study site provinces, with the highest test positivity proportion recorded in the rural northeast province of Kratie.

CONCLUSIONS

Surveillance data captured in this study provided a clinical and epidemiological characterization of positive CHIKV patients presenting at selected health facilities in Cambodia in 2020, and highlighted the widespread distribution of the outbreak, impacting both urban and rural locations. Findings also illustrated the importance of utilizing both RT-PCR and serological testing for effective CHIKV surveillance.

Review of Importance of Weather and Environmental Variables in Agent-Based Arbovirus Models

The study sought to review the works of literature on agent-based modeling and the influence of climatic and environmental factors on disease outbreak, transmission, and surveillance. Thus, drawing the influence of environmental variables such as vegetation index, households, mosquito habitats, breeding sites, and climatic variables including precipitation or rainfall, temperature, wind speed, and relative humidity on dengue disease modeling using the agent-based model in an African context and globally was the aim of the study. A search strategy was developed and used to search for relevant articles from four databases, namely, PubMed, Scopus, Research4Life, and Google Scholar. Inclusion criteria were developed, and 20 articles met the criteria and have been included in the review. From the reviewed works of literature, the study observed that climatic and environmental factors may influence the arbovirus disease outbreak, transmission, and surveillance. Thus, there is a call for further research on the area. To benefit from arbovirus modeling, it is crucial to consider the influence of climatic and environmental factors, especially in Africa, where there are limited studies exploring this phenomenon.

Advances in Computational Methods to Discover New NS2B-NS3 Inhibitors Useful Against Dengue and Zika Viruses

The Flaviviridae virus family consists of the genera Hepacivirus, Pestivirus, and Flavivirus, with approximately 70 viral types that use arthropods as vectors. Among these diseases, dengue (DENV) and zika virus (ZIKV) serotypes stand out, responsible for thousands of deaths worldwide. Due to the significant increase in cases, the World Health Organization (WHO) declared DENV a potential threat for 2019 due to being transmitted by infected travelers. Furthermore, ZIKV also has a high rate of transmissibility, highlighted in the outbreak in 2015, generating consequences such as Guillain-Barré syndrome and microcephaly. According to clinical outcomes, those infected with DENV can be asymptomatic, and in other cases, it can be lethal. On the other hand, ZIKV has severe neurological symptoms in newborn babies and adults. More serious symptoms include microcephaly, brain calcifications, intrauterine growth restriction, and fetal death. Despite these worrying data, no drug or vaccine is approved to treat these diseases. In the drug discovery process, one of the targets explored against these diseases is the NS2B-NS3 complex, which presents the catalytic triad His51, Asp75, and Ser135, with the function of cleaving polyproteins, with specificity for basic amino acid residues, Lys- Arg, Arg-Arg, Arg-Lys or Gln-Arg. Since NS3 is highly conserved in all DENV serotypes and plays a vital role in viral replication, this complex is an excellent drug target. In recent years, computer-aided drug discovery (CADD) is increasingly essential in drug discovery campaigns, making the process faster and more cost-effective, mainly explained by discovering new drugs against DENV and ZIKV. Finally, the main advances in computational methods applied to discover new compounds against these diseases will be presented here. In fact, molecular dynamics simulations and virtual screening is the most explored approach, providing several hit and lead compounds that can be used in further optimizations. In addition, fragment-based drug design and quantum chemistry/molecular mechanics (QM/MM) provides new insights for developing anti-DENV/ZIKV drugs. We hope that this review offers further helpful information for researchers worldwide and stimulates the use of computational methods to find a promising drug for treating DENV and ZIKV.

Towards the diagnosis of dengue virus and its serotypes using designed CRISPR/Cas13 gRNAs

Dengue Virus (DENV) is a mosquito-borne virus that is prevalent in the world's tropical and subtropical regions. Therefore, early detection and surveillance can help in the management of this disease. Current diagnostic methods rely primarily on ELISA, PCR, and RT-PCR, among others, which can only be performed in specialized laboratories and require sophisticated instruments and technical expertise. CRISPR-based technologies on the other hand have field-deployable viral diagnostics capabilities that could be used in the development of point-of-care molecular diagnostics. The first step in the field of CRISPR-based virus diagnosis is to design and screen gRNAs for high efficiency and specificity. In the present study, we employed a bioinformatics approach to design and screen DENV CRISPR/Cas13 gRNAs for conserved and serotype-specific variable genomic regions in the DENV genome. We identified one gRNA sequence specific for each of the lncRNA and NS5 regions and identified one gRNA against each of DENV1, DENV2, DENV3, and DENV4 to distinguish the four DENV serotypes. These CRISPR/Cas13 gRNA sequences will be useful in diagnosing the dengue virus and its serotypes for in vitro validation and diagnostics.

Diagnostic Accuracy of Various Immunochromatographic Tests for NS1 Antigen and IgM Antibodies Detection in Acute Dengue Virus Infection

Introduction: Rapid diagnostic tests (RDTs) were evaluated, in this paper, for their utility as a reliable test, using resource-constrained studies. In most studies, NS1 antigen and immunoglobulin M (IgM)-based immunochromatographic tests (ICTs) were considered for acute phase detection. We aimed to evaluate the diagnostic accuracy of NS1, IgM, and NS1/IgM-based ICTs to detect acute dengue virus (DENV) infection in dengue-endemic regions. Methods: Studies were electronically identified using the following databases: MEDLINE, Embase, Cochrane Library, Web of Science, and CINAHL Plus. Keywords including dengue, rapid diagnostic test, immunochromatography, sensitivity, specificity, and diagnosis were applied across databases. In total, 15 studies were included. Quality assessment of the included studies was performed using the QUADAS-2 tool. All statistical analyses were conducted using RevMan, MedCalc, and SPSS software. Results: The studies revealed a total of 4135 individuals, originating largely from the Americas and Asia. The prevalence of DENV cases was 53.8%. Pooled sensitivities vs. specificities for NS1 (only), IgM (only) and combined NS1/IgM were 70.97% vs. 94.73%, 40.32% vs. 93.01%, and 78.62% vs. 88.47%, respectively. Diagnostic odds ratio (DOR) of DENV for NS1 ICTs was 43.95 (95% CI: 36.61−52.78), for IgM only ICTs was 8.99 (95% CI: 7.25−11.16), and for NS1/IgM ICTs was 28.22 (95% CI: 24.18−32.95). ELISA ICTs yielded a DOR of 21.36, 95% CI: 17.08−26.741. RT-PCR had a DOR of 40.43, 95% CI: 23.3−71.2. Heterogeneity tests for subgroup analysis by ICT manufacturers for NS1 ICTs revealed an χ2 finding of 158.818 (df = 8), p < 0.001, whereas for IgM ICTs, the χ2 finding was 21.698 (df = 5), p < 0.001. Conclusion: NS1-based ICTs had the highest diagnostic accuracy in acute phases of DENV infection. Certain factors influenced the pooled sensitivity, including ICT manufacturers, nature of the infection, reference method (RT-PCR), and serotypes. Prospective studies may examine the best strategy for incorporating ICTs for dengue diagnosis.

Development of Highly Sensitive Sandwich ELISA for the Early-Phase Diagnosis of Chikungunya Virus Utilizing rE2-E1 Protein

Introduction

Chikungunya is caused by an alpha virus transmitted to humans by an infected mosquito. Infection is generally considered to be self-limiting and non-critical. Chikungunya infection may be diagnosed by severe joint pain with fever, but it is difficult to diagnose because the symptoms of chikungunya are common to many pathogens, including dengue fever. Diagnosis mainly depends on viral culture, reverse transcriptase polymerase chain reaction (RT-PCR), and IgM ELISA. Early and accurate diagnosis of the virus can be achieved by the application of PCR methods, but the high cost and the need for a thermal cycler restrict the use of such methods. On the other hand, antibody-based IgM ELISA is considered to be inexpensive, but antibodies against chikungunya virus (CHIKV) only develop after 4 days of infection, so it has limited application in the earlier diagnosis of viral infection and the management of patients. Because of these challenges, a simple antigen-based sensitive, specific, and rapid detection method is required for the early and accurate clinical diagnosis of chikungunya.

Methods

The amino acid sequence of CHIKV ectodomain E1 and E2 proteins was analyzed using bioinformatics tools to determine the antigenic residues, particularly the B-cell epitopes and their characteristics. Recombinant E2-E1 CHIKV antigen was used for the development of polyclonal antibodies in hamsters and IgG was purified. Serological tests of 96 CHIKV patients were conducted by antigen-capture ELISA using primary antibodies raised against rCHIKV E2-E1 in hamsters and human anti-CHIKV antibodies.

Results

We observed high specificity and sensitivity, of 100% and 95.8%, respectively, and these values demonstrate the efficiency of the test as a clinical diagnostic tool. There was no cross-reactivity with samples taken from dengue patients.

Discussion

Our simple and sensitive sandwich ELISA for the early-phase detection of CHIKV infection may be used to improve the diagnosis of chikungunya.

Artificial Intelligence-Based Cyber-Physical System for Severity Classification of Chikungunya Disease

Background: Artificial intelligence techniques are widely used in solving medical problems. Recently, researchers have used various deep learning techniques for the severity classification of Chikungunya disease. But these techniques suffer from overfitting and hyper-parameters tuning problems. Methods: In this paper, an artificial intelligence-based cyber-physical system (CPS) is proposed for the severity classification of Chikungunya disease. In CPS system, the physical components are integrated with computational algorithms to provide better results. Random forest (RF) is used to design the severity classification model for Chikungunya disease. However, RF suffers from overfitting and poor computational speed problems due to complex architectures and large amounts of connection weights. Therefore, an evolving RF model is proposed using the adaptive crossover-based genetic algorithm (ACGA). Results: ACGA can efficiently optimize the architecture of RF to achieve better results with better computational speed. Extensive experiments are performed by utilizing the Chikungunya disease dataset. Conclusion: Performance analysis demonstrates that ACGA-RF achieves higher performance as compared to the competitive models in terms of F-measure, accuracy, sensitivity, and specificity. The proposed CPS system can prevent users from visiting hospitals and can render services to patients living far away from hospitals.

Development of Nucleic Acid Lateral Flow Immunoassay for Rapid and Accurate Detection of Chikungunya Virus in Indonesia

Chikungunya fever is an arboviral disease caused by the Chikungunya virus (CHIKV). The disease has similar clinical manifestations with other acute febrile illnesses which complicates differential diagnosis in low-resource settings. We aimed to develop a rapid test for CHIKV detection based on the nucleic acid lateral flow immunoassay technology. The system consists of a primer set that recognizes the E1 region of the CHIKV genome and test strips in an enclosed cassette which are used to detect amplicons labeled with FITC/biotin. Amplification of the viral genome was done using open-source PCR, a low-cost open-source thermal cycler. Assay performance was evaluated using a panel of RNA isolated from patients' blood with confirmed CHIKV (n = 8) and dengue virus (n = 20) infection. The open-source PCR-NALFIA platform had a limit of detection of 10 RNA copies/ml. The assay had a sensitivity and specificity of 100% (95% CI: 67.56% - 100%) and 100% (95% CI: 83.89% - 100%), respectively, compared to reference standards of any positive virus culture on C6/36 cell lines and/or qRT-PCR. Further evaluation of its performance using a larger sample size may provide important data to extend its usefulness, especially its utilization in the peripheral healthcare facilities with scarce resources and outbreak situations.

Magnetic Multiplex Loop Mediated Isothermal Amplification (MM-LAMP) technique for simultaneous detection of dengue and chikungunya virus

Dengue and chikungunya viruses are arthropod borne virus spread through common vector instigating infection in human. There has been an increased recognition that more attention needs to be paid to similar sympotoms caused by both of the virus as they spread in the same region at same time. It warrants need of cost effective, user friendly and rapid multiplex diagnostic technique which could simultaneously diagnose and identify between two virus diseases in resource poor setting. A magnetic multiplex loop mediated isothermal amplification (MM-LAMP) technique was developed by coupling multiplex LAMP with magnetic particle-based naked eye visualization to overcome the shortcoming of simultaneous detection of both diseases. In recent years this technology has emerged as a particularly attractive candidate as amplification reaction process completes within 45 min. The first step involves multiplexing biotin and digoxigenin coated dengue and chikungunya primers respectively in LAMP reaction followed by precipitation of the amplified DNA with polyethylene glycol (PEG) buffer and finally clumping with streptavidin and anti-digoxigenin coated magnetic particle for virus discrimination and naked eye visualization. The DNA detection limit of MM LAMP visualization was 51.65 ng/μl which is comparable to the electrophoresis base UV light visualization. The results showed potential superiority over standard methods polymerase chain reaction (PCR). This current advancement empowers multiplex LAMP utility in resource limited setting without using any of the florescent dyes, turbidimeter, or the sophisticated quantitative PCR machine etc which restrict multiplex LAMP technique to laboratorial use only. We have proposed a novel method without such limitations. This technique has potential as a point of care technique for simultaneous detection of two diseases.

Natural biflavonoids as potential therapeutic agents against microbial diseases

Microbes broadly constitute several organisms like viruses, protozoa, bacteria, and fungi present in our biosphere. Fast-paced environmental changes have influenced contact of human populations with newly identified microbes resulting in diseases that can spread quickly. These microbes can cause infections like HIV, SARS-CoV2, malaria, nosocomial Escherichia coli, methicillin-resistant Staphylococcus aureus (MRSA), or Candida infection for which there are no available vaccines/drugs or are less efficient to prevent or treat these infections. In the pursuit to find potential safe agents for therapy of microbial infections, natural biflavonoids like amentoflavone, tetrahydroamentoflavone, ginkgetin, bilobetin, morelloflavone, agathisflavone, hinokiflavone, Garcinia biflavones 1 (GB1), Garcinia biflavones 2 (GB2), robustaflavone, strychnobiflavone, ochnaflavone, dulcisbiflavonoid C, tetramethoxy-6,6″-bigenkwanin and other derivatives isolated from several species of plants can provide effective starting points and become a source of future drugs. These biflavonoids show activity against influenza, severe acute respiratory syndrome (SARS), dengue, HIV-AIDS, coxsackieviral, hepatitis, HSV, Epstein-Barr virus (EBV), protozoal (Leishmaniasis, Malaria) infections, bacterial and fungal infections. Some of the biflavonoids can provide antiviral and protozoal activity by inhibition of neuraminidase, chymotrypsin-like protease, DV-NS5 RNA dependant RNA polymerase, reverse transcriptase (RT), fatty acid synthase, DNA polymerase, UL54 gene expression, Epstein-Barr virus early antigen activation, recombinant cysteine protease type 2.8 (r-CPB2.8), Plasmodium falciparum enoyl-acyl carrier protein (ACP) reductase or cause depolarization of parasitic mitochondrial membranes. They may also provide anti-inflammatory therapeutic activity against the infection-induced cytokine storm. Considering the varied bioactivity of these biflavonoids against these organisms, their structure-activity relationships are derived and wherever possible compared with monoflavones. Overall, this review aims to highlight these natural biflavonoids and briefly discuss their sources, reported mechanism of action, pharmacological uses, and comment on resistance mechanism, flavopiridol repurposing and the bioavailability aspects to provide a starting point for anti-microbial research in this area.

Advanced Lyophilised Loop Mediated Isothermal Amplification (L-LAMP) based point of care technique for the detection of dengue virus

Dengue virus infects millions of the people globally each year and its diagnosis remains a challenge. Conventionally used diagnostic methods are complex and time consuming. LAMP technique is a potential alternative for diagnosis of dengue virus. The benefits of LAMP are its ease and ability, as it does not require an expensive equipment and results are effortlessly visualized by the naked eye. However, it does not aid as point of care technique owing to need of contamination free area, deep freezer for chemical storage and primer self amplification. Each small modification in LAMP method bring it towards an ideal point of care technique. An advanced lyophilized loop mediated isothermal amplification (L-LAMP) was developed in which the dye was dried on the cap and reaction reagents was lyophilized at the bottom of the tube to overcome the common hurdles of LAMP technique. The technique was able to diagnose disease within 35 min with 4U of Bst polymerase. The least concentration of dye required was 1000×. Result given by the seminested reverse transcriptase polymerase chain reaction (RT-PCR) and L-LAMP with enzyme linked immuno sorbent assay (ELISA) were compared using Chi square test. The L-LAMP showed 100 % specificity and 92 % sensitivity with respect ELISA and was found better than RT-PCR which showed 100 % specificity and 88 % sensitivity. There was no cross reactivity of primers with other disease like malaria caused by Plasmodium falciparum and P. vivax and with viral disease chikungunya. L-LAMP has dynamic potential as point of care technique.

Detection and confirmation of dengue pre- and postintroduction of dengue NS1-antigen test at the University Malaya Medical Centre: An observational study

Early diagnosis of dengue is important to ensure proper management of patients and effective implementation of control measures. The present study was undertaken to determine the outcome of the implementation of dengue NS1-antigen (Ag) rapid diagnostic test (RDT) in the confirmation of dengue at the first patient hospital visit at the University Malaya Medical Centre. A total of 1036 and 1097 sera from the year 2008 and 2015 were used, representing samples from before and after dengue NS1-Ag RDT was implemented as routine diagnostic at the hospital. Results showed that similar dengue confirmation percentage (56%) was made in 2008 and 2015, regardless of the main laboratory diagnostic method used. Confirmation of dengue, however, increased to 68% and 73% when dengue NS1-Ag test or dengue immunoglobulin M-capture enzyme-linked immunosorbent assay was used as the second test for the 2008 and 2015 samples, respectively. Detection of dengue virus (DENV) using multiplex reverse transcription-polymerase chain reaction (RT-PCR) showed that DENV-1 was the highest in circulation in 2008 and that both DENV-1 and DENV-2 were dominant in 2015. In summary, the present study demonstrated that the introduction and use of the dengue NS1-Ag RDT did not change or compromise confirmation of dengue, highlighting the advantage of using the method. With the reducing cost of molecular detection tools, DENV detection using RT-PCR remains a viable option for further confirmation of dengue in hospital settings.

Independent Evaluation of Two Prototype Immunochromatographic Tests for Dengue Fever Developed by InBios

INTRODUCTION

Dengue fever, caused by any of the four dengue viruses (DENV1-4), is endemic in more than 100 countries around the world. Each year, up to 400 million people get infected with dengue virus. It is one of the most important arthropod-borne viral diseases. Dengue's global presence poses a medical threat to deploying military personnel and their dependents. An accurate diagnosis followed by attentive supportive care can improve outcomes in patients with severe dengue disease. Dengue diagnostic tests based on PCR and ELISA platforms have been developed and cleared by the U.S. FDA. However, these diagnostic assays are laborious and usually require highly trained personnel and specialized equipment, which presents a significant challenge when conducting operations in austere and resource-constrained areas. InBios International, Inc. (Seattle, WA) has developed two rapid and instrument-free immunochromatographic test prototype devices (multiplex and traditional formats) for dengue diagnosis.

MATERIALS AND METHODS

To determine the performance of the InBios immunochromatographic tests, 183 clinical samples were tested on both prototype devices. Both assays were performed without any instruments and the results were read in 20 minutes.

RESULTS

The traditional format had better overall performance (sensitivity: 97.4%; specificity: 90%) than the multiplex format (sensitivity: 86.9%; specificity: 63.3%). The traditional format was superior in serotype-specific detection with 100% overall sensitivity for DENV1, DENV3, and DENV4 and 93.3% sensitivity for DENV2 compared to the multiplex format (91.7%, 78.3%, 83.3%, and 96.3% for DENV1, 2, 3, and 4, respectively). The traditional format was easier to read than the multiplex format. The multiplex format was simpler and faster to set up than the traditional format.

CONCLUSIONS

The InBios traditional format had a better overall performance and readability profile than the multiplex format, while the multiplex format was easier to set up. Both formats were highly sensitive and specific, were easy to perform, and did not require sophisticated equipment. They are ideal for use in resource-limited settings where dengue is endemic. Based on our overall assessment, the traditional format should be considered for further development and used in the upcoming multicenter clinical trial toward FDA clearance.

Efficient Plant Production of Recombinant NS1 Protein for Diagnosis of Dengue

Dengue fever is endemic in more than 120 countries, which account for 3.9 billion people at risk of infection worldwide. The absence of a vaccine with effective protection against the four serotypes of this virus makes differential molecular diagnosis the key step for the correct treatment of the disease. Rapid and efficient diagnosis prevents progression to a more severe stage of this disease. Currently, the limiting factor in the manufacture of dengue (DENV) diagnostic kits is the lack of large-scale production of the non-structural 1 (NS1) protein (antigen) to be used in the capture of antibodies from the blood serum of infected patients. In this work, we use plant biotechnology and genetic engineering as tools for the study of protein production for research and commercial purposes. Gene transfer, integration and expression in plants is a valid strategy for obtaining large-scale and low-cost heterologous protein production. The authors produced NS1 protein of the dengue virus serotype 2 (NS1DENV2) in the Arabidopsis thaliana plant. Transgenic plants obtained by genetic transformation expressed the recombinant protein that was purified and characterized for diagnostic use. The yield was 203 μg of the recombinant protein per gram of fresh leaf. By in situ immunolocalization, transgenic protein was observed within the plant tissue, located in aggregates bodies. These antigens showed high sensitivity and specificity to both IgM (84.29% and 91.43%, respectively) and IgG (83.08% and 87.69%, respectively). The study goes a step further to validate the use of plants as a strategy for obtaining large-scale and efficient protein production to be used in dengue virus diagnostic tests.

Age-dependent seroprevalence of dengue and chikungunya: inference from a cross-sectional analysis in Esmeraldas Province in coastal Ecuador

OBJECTIVES

There are few population-based estimates for prevalence of past exposure to dengue and chikungunya viruses despite common epidemiological features. Here, we have developed a novel statistical method to study patterns of age-dependent prevalence of immunity in a population following exposures to two viruses which share similar epidemiological features including mode of transmission and induction of long-lasting immunity. This statistical technique accounted for sociodemographic characteristics associated with individuals and households.

SETTINGS

The data consist of a representative sample from an ongoing longitudinal birth cohort set-up in a tropical district in coastal Ecuador (Esmeraldas).

PARTICIPANTS

We collected data and blood samples from 319 individuals belonging to 152 households following epidemics of the infections in 2015 in Latin America.

PRIMARY OUTCOME

Plasma was tested for the presence of specific IgG antibodies to dengue and chikungunya viruses by commercial ELISA and defined a bivariate binary outcome indicating individuals' past exposure status to dengue and chikungunya (ie, presence/absence of IgG antibodies to dengue or chikungunya or both).

RESULTS

Dengue seroprevalence increased rapidly with age reaching 97% (95% credible interval (CrI): 93%-99%) by 60 years. Chikungunya seroprevalence peaked at 42% (95% CrI: 18%-66%) around 9 years of age and averaged 27% (95% CrI: 8.7%-51.6%) for all ages. Rural areas were more likely to be associated with dengue-only exposure while urban areas and shorter distance to the nearest household were associated with exposures to both. Women living in urban settings were more likely to be chikungunya seropositive while rural men were more likely to be dengue seropositive.

CONCLUSION

Dengue seroprevalence was strongly age dependent consistent with endemic exposure while that of chikungunya peaked in childhood consistent with the recent emergence of the virus in the study area. Our findings will inform control strategies for the two arboviruses in Ecuador including recommendations by the WHO on dengue vaccination.

An overview of the current medical literature on Zika virus

Zika virus is a member of the family of Flaviviridae, which is primarily spread to humans by mosquito bites. It has been linked to microcephaly in neonates, and as such, it poses a significant risk to human pregnancy. Zika virus infection is also implicated in other severe neurological disorders such as Guillain-Barre syndrome. There is currently no vaccine available to treat Zika virus disease, and as such, it represents a serious challenge to public health. Antigenic similarities between Zika and dengue can suggest artificially high infection rates of Zika within specific population groups. Here, we review recent literature and provide an update on the status of the Zika outbreak, including a description of available medical countermeasure options and current diagnosis methodology.

Development and Validation of a Rapid Lateral Flow E1/E2-Antigen Test and ELISA in Patients Infected with Emerging Asian Strain of Chikungunya Virus in the Americas

Since its 2013 emergence in the Americas, Chikungunya virus (CHIKV) has posed a serious threat to public health. Early and accurate diagnosis of the disease, though currently lacking in clinics, is integral to enable timely care and epidemiological response. We developed a dual detection system: a CHIKV antigen E1/E2-based enzyme-linked immunosorbent assay (ELISA) and a lateral flow test using high-affinity anti-CHIKV antibodies. The ELISA was validated with 100 PCR-tested acute Chikungunya fever samples from Honduras. The assay had an overall sensitivity and specificity of 51% and 96.67%, respectively, with accuracy reaching 95.45% sensitivity and 92.03% specificity at a cycle threshold (Ct) cutoff of 22. As the Ct value decreased from 35 to 22, the ELISA sensitivity increased. We then developed and validated two lateral flow tests using independent antibody pairs. The sensitivity and specificity reached 100% for both lateral flow tests using 39 samples from Colombia and Honduras at Ct cutoffs of 20 and 27, respectively. For both lateral flow tests, sensitivity decreased as the Ct increased after 27. Because CHIKV E1/E2 are exposed in the virion surfaces in serum during the acute infection phase, these sensitive and specific assays demonstrate opportunities for early detection of this emerging human pathogen.

Evaluation of a Newly Developed Rapid Automated Fluorescent Lateral Flow Immunoassay to Detect IgG and IgM Antibodies to Chikungunya Virus

The ichroma Chikungunya virus (CHIKV) IgG/IgM (Boditech Med Inc., Chuncheon, Korea) is a newly developed rapid lateral flow immunoassay for detection of anti- CHIKV-IgG/IgM. This study conducted with thirty-six anti-CHIKV IgG positive sera, 57 anti-CHIKV IgM positive sera and 163 anti-CHIKV IgG/IgM negative sera which were confirmed by commercial enzyme-linked immunosorbent assays (ELISAs) (Inbios CHIKjj Detect™ IgM Capture ELISA, Inbios CHIKjj Detect™ IgG ELISA (InBios International Inc., Seattle, WA, USA), Anti-CHIKV ELISA (IgM), Anti- CHIKV ELISA (IgG) (Euroimmun, Lübeck, Germany)). The ichroma detected all 36 anti-CHIKV IgG and 57 anti-CHIKV IgM positivity (100% sensitivity). For 163 anti-CHIKV IgG/IgM negative sera, the ichroma showed one false positive for IgM (99.4% specificity). The ichroma showed no cross-reactivity and no interference. The ichroma demonstrated good diagnostic performance compared to the current ELISAs.

Importation of dengue, Zika and chikungunya infections in Europe: the current situation in Greece

Although several arboviruses-such as dengue (DENV), Zika (ZIKV) and chikungunya (CHIKV) viruses-are not endemic in Europe, they have the potential to emerge following importation of the virus, taking advantage of the favourable climate and ecosystem. DENV, ZIKV and CHIKV are transmitted by Aedes species mosquitoes and are amongst the most common travel-associated arboviruses. Furthermore, they are linked to sporadic, local outbreaks, especially in the southern parts of Europe. In this review we present in brief the DENV, ZIKV and CHIKV cases imported to Greece during the last 6 years (2013-2018), and we describe the recent laboratory data obtained from the Hellenic Pasteur Institute and the National Reference Centre for Arboviruses. We report 21 imported cases of DENV, ZIKV and CHIKV infections in travellers arriving in Greece. The probable origins were south-eastern Asian (71%) and north-central American (29%) countries. Furthermore, we stress the importance of early and accurate diagnosis in spite of a plethora of diagnostic challenges that clinicians and virologists have to face. Altogether, with the authorities' awareness and the preventive measures to be applied, local transmission events can be successfully avoided, especially in summer when the temperature is favourable for mosquito-borne infections.

Molecular Detection of Dengue Virus in Mosquitoes as an Early Indicator to Aid in the Prevention of Human Infection in Endemic Areas

Human cases of dengue virus based on the National Dengue Control Plan were compared with the molecular detection of the dengue virus in trapped mosquitoes, verifying the prediction and efficacy potentials of vector control between the two methodologies in a city with three endemic frontiers. Molecular detection of dengue virus in trapped mosquitoes was significantly higher than in human cases (p = 0.0435). Thus, molecular detection could be used as an early indicator to help prevent more human cases of dengue.

Molecular and phylogenetic analysis of Chikungunya virus in Central India during 2016 and 2017 outbreaks reveal high similarity with recent New Delhi and Bangladesh strains

Central India witnessed Chikungunya virus (CHIKV) outbreaks in 2016 and 2017. The present report is a hospital based cross-sectional study on the serological and molecular epidemiology of the outbreak. Mutational and phylogenetic analysis was conducted to ascertain the genetic relatedness of the central Indian strains with other Indian and global strains. Chikungunya infection was confirmed in the clinically suspected patients by the detection of anti-CHIKV IgM antibody by ELISA and viral RNA by RT-PCR. A representative set of the RT-PCR positive samples were sequenced for E1 gene and analyzed to identify the emerging mutations and establish their phylogenetic relationship, particularly with other contemporary strains. Phylogenetic analysis revealed the present strains to be of East Central South African (ECSA) genotype. Emergence of a variant strain was observed in the year 2016, which became the predominant strain in this region in 2017. The strains showed significant identity with recent New Delhi strains of 2015 and 2016 and Bangladesh strains of 2017. The epidemic mutation A226V which emerged in 2006 outbreaks of India and Indian Ocean Islands was found to be absent in the current strains. Among the important mutations viz. K211E, M269 V, D284E, I317V & V322A observed in the recent strains. I317V is a novel mutation which has emerged very recently as it was found only in central Indian (2016, 2017), New Delhi strains (2015, 2016) and Bangladesh strains (2017). This study has identified a unique mutation E1:I317V in the Central Indian strains, which is present only in recent New Delhi and Bangladesh strains till date. This study highlights the need for continuous molecular surveillance of circulating CHIKV strains in order to facilitate the prompt identification of novel strains of this virus and enable the elucidation of their clinical correlates.

Development of a Specific CHIKV-E2 Monoclonal Antibody for Chikungunya Diagnosis

Chikungunya fever is a vector-borne viral disease transmitted to humans by chikungunya virus (CHIKV)-infected mosquitoes. There have been many outbreaks of CHIKV infection worldwide, and the virus poses ongoing risks to global health. To prevent and control CHIKV infection, it is important to improve the current CHIKV diagnostic approaches to allow for the detection of low CHIKV concentrations and to correctly distinguish CHIKV infections from those due to other mosquito-transmitted viruses, including dengue virus (DENV), Japanese encephalitis virus (JEV), and Zika virus (ZIKV). Here, we produced monoclonal antibodies (mAbs) against the CHIKV envelope 2 protein (CHIKV-E2) and compared their sensitivity and specificity with commercially available mAbs using enzyme-linked immunosorbent assays (ELISA). Two anti-CHIKV-E2 mAbs, 19-1 and 21-1, showed higher binding affinities to CHIKV-E2 protein than the commercial mAbs did. In particular, the 19-1 mAb had the strongest binding affinity to inactivated CHIKV. Moreover, the 19-1 mAb had very little cross-reactivity with other mosquito-borne viruses, such as ZIKV, JEV, and DENV. These results suggest that the newly produced anti-CHIKV-E2 mAb, 19-1, could be used for CHIKV diagnostic approaches.

Undetected Chikungunya virus co-infections in a Brazilian region presenting hyper-endemic circulation of Dengue and Zika

BACKGROUND

Chikungunya virus (CHIKV) causes a disease characterized by acute onset of fever accompanied by arthralgia. Clinical similarities and co-circulation of other arboviruses such as Dengue virus (DENV) and Zika virus (ZIKV), have complicated their differentiation, making their diagnoses a challenge for the health authorities. Misdiagnosis is a serious issue to the management of patients and development of public health measures.

OBJECTIVES

We carried out further screening of CHIKV, DENV and ZIKV cases in Minas Gerais, Brazil, after diagnostics were already issued by a state laboratory and according to the Brazilian Ministry of Health (BMH) policy. Our aim was to look for possible co-infections or previous arboviruses' exposure.

STUDY DESIGN

Sera from 193 patients with symptoms of arboviral infections were tested for DEV, ZKV and/or CHIKV by the State laboratory, according to clinical suspicion and following standard BMH guidelines. After an official diagnosis was issued for each patient, we retested samples applying a broader panel of ELISA-based serological tests.

RESULTS

We identified 13 patients with concurrent or consecutive infections (IgM positive for more than one arbovirus), including 11 individuals that were positive for CHIKV and other previously confirmed arbovirus infection.

DISCUSSION

Guidelines established in many arbovirus-endemic countries prioritizes the diagnosis of Zika and Dengue and no further analyzes are done when samples are positive for those viruses. As a result, possible cases of co-infections with chikungunya are neglected, which affects the epidemiological assessments of virus circulation, patient management, and the development of public health policies.

Zika Virus: A Global Public Health Menace: A Comprehensive Update

Zika virus (ZIKV) is a RNA virus and belongs to genus Flavivirus and family Flaviviridae. The virus was first discovered from a febrile primate from the Zika forests of Uganda in 1947 and the first human case was documented in 1954. The nonspecific clinical manifestations of ZIKV pose diagnostic dilemmas and delays early and effective treatment. Dental professionals should have a thorough knowledge about the virus and should follow standard infection control measures as the virus has been demonstrated in various body secretions (including salivary secretions). The disease is managed by symptomatic and supportive care and no vaccine exist till date. Recent ZIKV outbreaks and increase association of microcephaly with congenital ZIKV and neurological complications (Guillain-Barré syndrome) has drawn global public health attention. The World Health Organization declared it a public health emergency of international concern in 2016. This review article provides a detailed overview on ZIKV; it is clinical and oral manifestations, diagnostic aids, differential diagnosis, preventive aspects, and management protocol.

The Surveillance of Chikungunya Virus in a Temperate Climate: Challenges and Possible Solutions from the Experience of Lazio Region, Italy

CHIKV has become an emerging public health concern in the temperate regions of the Northern Hemisphere as a consequenceof the expansion of the endemic areas of its vectors (mainly Aedes aegypti and Aedesalbopictus). In 2017, a new outbreak of CHIKV was detected in Italy with three clusters of autochthonous transmission in the Lazio Region (central Italy), in the cities of Anzio, Rome, and Latina and a secondary cluster in the Calabria Region (south Italy). Given the climate characteristics of Italy, sporadic outbreaks mostly driven by imported cases followed by autochthonous transmission could occur during the summer season. This highlights the importance of a well-designed surveillance system, which should promptly identify autochthonous transmission. The use of a surveillance system integrating different surveillance tools, including entomological surveillance in a one health approach, together with education of the health care professionals should facilitate the detection, response, and control of arboviruses spreading.

What Does the Future Hold for Yellow Fever Virus? (II)

As revealed by the recent resurgence of yellow fever virus (YFV) activity in the tropical regions of Africa and South America, YFV control measures need urgent rethinking. Over the last decade, most reported outbreaks occurred in, or eventually reached, areas with low vaccination coverage but that are suitable for virus transmission, with an unprecedented risk of expansion to densely populated territories in Africa, South America and Asia. As reflected in the World Health Organization's initiative launched in 2017, it is high time to strengthen epidemiological surveillance to monitor accurately viral dissemination, and redefine vaccination recommendation areas. Vector-control and immunisation measures need to be adapted and vaccine manufacturing must be reconciled with an increasing demand. We will have to face more yellow fever (YF) cases in the upcoming years. Hence, improving disease management through the development of efficient treatments will prove most beneficial. Undoubtedly, these developments will require in-depth descriptions of YFV biology at molecular, physiological and ecological levels. This second section of a two-part review describes the current state of knowledge and gaps regarding the molecular biology of YFV, along with an overview of the tools that can be used to manage the disease at the individual, local and global levels.

Prevalence of dengue and leptospirosis co-infection in a tertiary care hospital in south India

BACKGROUND AND OBJECTIVES

Dengue and Leptospirosis were often discussed separately with rash being more common in dengue and jaundice in leptospirosis. But with increasing reports of co-infection, the situation has become worse. The main objective of this study was to look for the presence of both Dengue and Leptospira IgM antibodies in serum samples of patients, presenting with acute febrile illness. Medical records of the co-infected patients were examined to analyse the clinical features and laboratory findings.

MATERIALS AND METHODS

Serum samples of patients presenting with acute febrile illness were screened for the presence of Dengue IgM antibodies and Leptospira antibodies. Clinical features and laboratory parameters of patients with co-infection were compared with patients having dengue alone. Rainfall data was obtained to look for an association between rainfall and Dengue, leptospirosis and co-infected cases.

RESULTS

Co-infection was seen in 33 (3.4%) samples. There was a statistically significant association between clinical features like rashes, bleeding gums and co-infection. There was a statistically significant association between various laboratory parameters like thrombocytopenia and co-infection. There was positive correlation between rainfall and development of dengue, leptospirosis, and co-infection but it was not statistically significant.

CONCLUSION

The overall prevalence of co-infection was 3.4%. This study re-emphasizes the fact that dengue and leptospirosis are widely prevalent in south India and clinicians should be aware that co-infection with dengue and leptospirosis is not uncommon.

Chikungunya in a Pediatric Traveler

Chikungunya is a mosquito-transmitted virus found primarily in Africa and Asia. In late 2013, chikungunya virus emerged in the Western hemisphere, spreading from the Caribbean to South, Central, and North America (MMWR Morb Mortal Wkly Rep. 2014;63:1121-1128). Symptoms can be similar to nonspecific viral presentations including fever, joint pain, joint swelling, and rash. The diagnosis of infectious tropical diseases in the emergency department often requires a high index of suspicion, given the nonspecific early findings that characterize many of these tropical diseases. This report presents a case of chikungunya in a pediatric patient traveling from Guatemala to the United States. Proper recognition of infection and diagnosis are vital from a public health perspective. Considering patients will remain viremic for up to a week and potentially expose local mosquitoes to infection, it is important to educate the patient on mosquito bite prevention in geographic areas of the United States where competent mosquito vectors exist as a means of avoiding further spread.

Co-protoporphyrin IX and Sn-protoporphyrin IX inactivate Zika, Chikungunya and other arboviruses by targeting the viral envelope

The global situation of diseases transmitted by arthropod-borne viruses such as Dengue (DENV), Yellow Fever (YFV), Chikungunya (CHIKV) and Zika (ZIKV) viruses is alarming and treatment of human infection by these arboviruses faces several challenges. The discovery of broad-spectrum antiviral molecules, able to inactivate different groups of viruses, is an interesting approach. The viral envelope is a common structure among arboviruses, being a potential target for antivirals. Porphyrins are amphipathic molecules able to interact with membranes and absorb light, being widely used in photodynamic therapy. Previously, we showed that heme, Co-protoporphyrin IX (CoPPIX) and Sn-protoporphyrin IX (SnPPIX) directly inactivate DENV and YFV infectious particles. Here we demonstrate that the antiviral activity of these porphyrins can be broadened to CHIKV, ZIKV, Mayaro virus, Sindbis virus and Vesicular Stomatitis virus. Porphyrin treatment causes viral envelope protein loss, affecting viral morphology, adsorption and entry into target cells. Also, light-stimulation enhanced the SnPPIX activity against all tested arboviruses. In summary, CoPPIX and SnPPIX were shown to be efficient broad-spectrum compounds to inactivate medically and veterinary important viruses.

Laboratory preparedness and response with a focus on arboviruses in Europe

BACKGROUND

The global health burden of arboviruses is continuously rising, which results in increasing pressure on local and (inter)national laboratory infrastructures. Timely and accurate diagnosis of cases is one of the main pillars for public health and clinical responses to an arbovirus emergence.

AIMS AND SOURCES

This narrative review aims to summarize recent advances and to identify needs in laboratory preparedness and response activities, with a focus on viruses transmitted by arthropods in Europe. The review is based on evidence extracted from PubMed searches, Public Health and clinical laboratory experiences from the authors and the authors' opinions substantiated by peer-reviewed scientific literature.

CONTENT

We illustrate the importance of inter-epidemic laboratory preparedness activities to ensure adequate Public Health and clinical responses. We describe the status of arbovirus endemicity and emergence in Europe thereby highlighting the need for preparedness for these viruses. We discuss the components and pitfalls of an adequate laboratory preparedness and response and the broader context of the current landscape of international research, clinical and laboratory preparedness networks. The complexity of arbovirus laboratory preparedness and response is described.

IMPLICATIONS

Outbreak preparedness plans need to look beyond national reference laboratories, to include first-line responding onsite hospital laboratories and plans for strengthening of such local capacity and capability as required depending on the nature of the outbreak. In particular, the diagnosis of arbovirus infections is complicated by the existence of geographic overlap of circulation of numerous arboviruses, the overlap in clinical manifestation between many arboviruses and other aetiologies and the existence of cross-reactivity between related arboviruses in serology testing. Inter-epidemic preparedness activities need strong national and international networks addressing these issues. However, the current mushrooming of European preparedness networks requires governance to bring the European preparedness and response to a next level.

Acute undifferentiated fever in India: a multicentre study of aetiology and diagnostic accuracy

Background

The objectives of this study were to determine the proportion of malaria, bacteraemia, scrub typhus, leptospirosis, chikungunya and dengue among hospitalized patients with acute undifferentiated fever in India, and to describe the performance of standard diagnostic methods.

Methods

During April 2011–November 2012, 1564 patients aged ≥5 years with febrile illness for 2–14 days were consecutively included in an observational study at seven community hospitals in six states in India.

Malaria microscopy, blood culture, Dengue rapid NS1 antigen and IgM Combo test, Leptospira IgM ELISA, Scrub typhus IgM ELISA and Chikungunya IgM ELISA were routinely performed at the hospitals.

Second line testing, Dengue IgM capture ELISA (MAC-ELISA), Scrub typhus immunofluorescence (IFA), Leptospira Microscopic Agglutination Test (MAT), malaria PCR and malaria immunochromatographic rapid diagnostic test (RDT) Parahit Total™ were performed at the coordinating centre. Convalescence samples were not available.

Case definitions were as follows: Leptospirosis: Positive ELISA and positive MAT. Scrub typhus: Positive ELISA and positive IFA. Dengue: Positive RDT and/or positive MAC-ELISA. Chikungunya: Positive ELISA. Bacteraemia: Growth in blood culture excluding those defined as contaminants. Malaria: Positive genus-specific PCR.

Results

Malaria was diagnosed in 17% (268/1564) and among these 54% had P. falciparum. Dengue was diagnosed in 16% (244/1564). Bacteraemia was found in 8% (124/1564), and among these Salmonella typhi or S. paratyphi constituted 35%. Scrub typhus was diagnosed in 10%, leptospirosis in 7% and chikungunya in 6%. Fulfilling more than one case definition was common, most frequent in chikungunya where 26% (25/98) also had positive dengue test.

Conclusions

Malaria and dengue were the most common causes of fever in this study. A high overlap between case definitions probably reflects high prevalence of prior infections, cross reactivity and subclinical infections, rather than high prevalence of coinfections. Low accuracy of routine diagnostic tests should be taken into consideration when approaching the patient with acute undifferentiated fever in India.

Recommendations of the Brazilian Society of Rheumatology for diagnosis and treatment of Chikungunya fever. Part 1 - Diagnosis and special situations

Chikungunya fever has become a relevant public health problem in countries where epidemics occur. Until 2013, only imported cases occurred in the Americas, but in October of that year, the first cases were reported in Saint Marin island in the Caribbean. The first autochthonous cases were confirmed in Brazil in September 2014; until epidemiological week 37 of 2016, 236,287 probable cases of infection with Chikungunya virus had been registered, 116,523 of which had serological confirmation. Environmental changes caused by humans, disorderly urban growth and an ever-increasing number of international travelers were described as the factors responsible for the emergence of large-scale epidemics. Clinically characterized by fever and joint pain in the acute stage, approximately half of patients progress to the chronic stage (beyond 3 months), which is accompanied by persistent and disabling pain. The aim of the present study was to formulate recommendations for the diagnosis and treatment of Chikungunya fever in Brazil. A literature review was performed in the MEDLINE, SciELO and PubMed databases to ground the decisions for recommendations. The degree of concordance among experts was established through the Delphi method, involving 2 in-person meetings and several online voting rounds. In total, 25 recommendations were formulated and divided into 3 thematic groups: (1) clinical, laboratory and imaging diagnosis; (2) special situations; and (3) treatment. The first 2 themes are presented in part 1, and treatment is presented in part 2.

Knowledge and practice regarding dengue and chikungunya: a cross-sectional study among Healthcare workers and community in Northern Tanzania

OBJECTIVE

To investigate knowledge and prevention practices regarding dengue and chikungunya amongst community members, as well as knowledge, treatment and diagnostic practices among healthcare workers.

METHOD

We conducted a cross-sectional survey with 125 community members and 125 healthcare workers from 13 health facilities in six villages in the Hai district of Tanzania. A knowledge score was generated based on participant responses to a structured questionnaire, with a score of 40 or higher (of 80 and 50 total scores for community members and healthcare workers, respectively) indicating good knowledge. We conducted qualitative survey (n = 40) to further assess knowledge and practice regarding dengue and chikungunya fever.

RESULTS

15.2% (n = 19) of community members had good knowledge regarding dengue, whereas 53.6%, (n = 67) of healthcare workers did. 20.3% (n = 16) of participants from lowland areas and 6.5% (n = 3) from highland areas had good knowledge of dengue (χ² = 4.25, P = 0.03). Only 2.4% (n = 3) of all participants had a good knowledge score for chikungunya. In the qualitative study, community members expressed uncertainty about dengue and chikungunya. Some healthcare workers thought that they were new diseases.

CONCLUSION

There is insufficient knowledge regarding dengue and chikungunya fever among community members and healthcare workers. Health promotion activities on these diseases based on Ecological Health Mode components to increase knowledge and improve preventive practices should be developed.

Seroprevalence of Asymptomatic Dengue Virus Infection and Its Antibodies Among Healthy/Eligible Saudi Blood Donors: Findings From Holy Makkah City

BACKGROUND

Threat to blood transfusion-transmitted dengue virus (DENV) and its antibodies has recently emerged worldwide. Dengue fever is an endemic disease in Saudi Arabia, particularly in its Western region. The aim of this study was to estimate the seroprevalence of asymptomatic DENV infection and its antibodies among eligible Saudi blood donors.

METHODS

Serum samples from 910 healthy/eligible adult male Saudi blood donors, who reside in Holy Makkah City of Saudi Arabia, were collected between March 2015 and August 2016 and screened for the detection of DENV nonstructural protein 1 (NS1) antigen and anti-DENV IgM and IgG antibodies using commercial enzyme-linked immunosorbent assay kits (Panbio, Brisbane, QLD, Australia).

RESULTS

Among the tested donors, 48 (5.3%) were seropositive for DENV-NS1 antigen, whereas 50 (5.5%) and 354 (38.9%) were seropositive for anti-DENV IgM and IgG antibodies, respectively. Seropositivity for DENV-NS1 antigen and/or anti-DENV IgM antibody among the tested donors reflects their ongoing asymptomatic viremic infectious stage with DENV during their donation time, whereas high prevalence of anti-DENV IgG seropositivity reflects the high endemicity of dengue disease in this region of Saudi Arabia.

CONCLUSIONS

These results show high prevalence of asymptomatic DENV infection and its antibodies among Saudi blood donors, raising the importance of establishing blood screening for dengue disease at different blood donation services and units in Saudi Arabia to improve the guarantee of blood transfusions and to control DENV dissemination.

Mosquito Exposure and Chikungunya and Dengue Infection Among Travelers During the Chikungunya Outbreak in the Americas

AbstractTravelers are at risk for arbovirus infection. We prospectively enrolled 267 Department of Defense beneficiaries traveling to chikungunya-outbreak regions in the Americas between December 2013 and May 2015 and assessed travel characteristics and serologic exposure to chikungunya virus (CHIKV) and dengue virus (DENV). Ten ill-returning travelers were also assessed retrospectively. Self-reported mosquito exposure was common (64% of 198 evaluable travelers saw mosquitoes; 53% of 201 reported ≥ 1 bite). Increased exposure was associated with active-duty travelers (odds ratio [OR] = 2.6 [1.3-5.4] for seeing mosquitoes) or travelers visiting friends and relatives (VFR) (OR = 3.5 [1.0-10.0] for high-intensity bite exposure). Arbovirus infection was defined as seroconversion on plaque reduction neutralization testing (PRNT) of pre- and posttravel sera. For ill subjects enrolled posttravel, infection was defined by a positive convalescent PRNT and/or a positive reverse transcription polymerase chain reaction for CHIKV or DENV. We identified seven cases of arbovirus infection: four with CHIKV, five with DENV, and two with both. The composite attack rate for CHIKV and DENV infection was 3.7% of 108 evaluable, immunologically naïve, prospectively assessed travelers; there was serologic and/or polymerase chain reaction evidence of arbovirus infection in three of four evaluable (three of 10 total) ill-returning travelers. We identified both symptomatic and asymptomatic cases. Military purpose of travel and VFR travel accounted for five of seven cases. Pretravel counseling is important and should target higher risk groups. Given a shared vector between CHIKV, DENV, and Zika virus (ZIKV), this study can also help guide counseling for travelers to ZIKV-outbreak regions.

Zika Virus-Induced Microcephaly and Its Possible Molecular Mechanism

Zika virus is an arthropod-borne re-emerging pathogen associated with the global pandemic of 2015-2016. The devastating effect of Zika viral infection is reflected by its neurological manifestations such as microcephaly in newborns. This scenario evoked our interest to uncover the neurotropic localization, multiplication of the virus, and the mechanism of microcephaly. The present report provides an overview of a possible molecular mechanism of Zika virus-induced microcephaly based on recent publications. Transplacental transmission of Zika viral infection from mother to foetus during the first trimester of pregnancy results in propagation of the virus in human neural progenitor cells (hNPCs), where entry is facilitated by the receptor (AXL protein) leading to the alteration of signalling and immune pathways in host cells. Further modification of the viral-induced TLR3-mediated immune network in the infected hNPCs affects viral replication. Downregulation of neurogenesis and upregulation of apoptosis in hNPCs leads to cell cycle arrest and death of the developing neurons. In addition, it is likely that the environmental, physiological, immunological, and genetic factors that determine in utero transmission of Zika virus are also involved in neurotropism. Despite the global concern regarding the Zika-mediated epidemic, the precise molecular mechanism of neuropathogenesis remains elusive.

Mosquito-transmitted viruses - the great Brazilian challenge

Arboviruses pose a serious threat to public health worldwide, overloading the healthcare system and causing economic losses. These viruses form a very diverse group, and in Brazil, arboviruses belonging to the families Flaviviridae and Togaviridae are predominant. Unfortunately, the number of arboviruses increases in proportion with factors such as deforestation, poor sanitation, climate changes, and introduction of new viruses like Chikungunya virus and Zika virus. In Brazil, dengue is endemic, along with the presence of other arboviruses. The situation is complicated by the scarcity of diagnostic infrastructure and the absence of approved vaccines for these diseases. Disease control, thus, relies solely on vector control. Therefore, enhanced clinical knowledge and improved general awareness about these arboviruses are indispensable to tackle diagnostic inadequacies.