Dengue virus infection: epidemiology, pathogenesis, clinical presentation, diagnosis, and prevention

Early transcriptomic host response signatures in the serum of dengue patients provides insights into clinical pathogenesis and disease severity

Dengue virus (DENV), known to cause viral infection, belongs to the family Flaviviridae, having four serotypes (DENV1-4) that spreads by the bite of the Aedes aegypti mosquito. India has been suffering from dengue outbreaks annually with widespread epidemics by prevalence of all the four DENV serotypes. The diverse spectrum of clinical manifestations in dengue infection, mild to severe forms, makes the need of timely diagnosis and prompt treatment an essence. The identification of a dengue host response signature in serum can increase the understanding of dengue pathogenesis since most dengue NS1 Ag tests have been developed and evaluated in serum samples. Here, to understand the same, we undertook a dual RNA-sequencing (RNA-Seq) based approach from the serum samples of dengue-infected patients. The results thus yield the early transcriptional signatures that discriminated the high viral reads patients from patients who had low dengue viral reads. We identified a significant upregulation of two sets of genes, key antiviral (IFIT3, RSAD2, SAT1) and vascular dysfunction (TNFS10, CXCL8) related genes in the high viral reads group. Deeper delving of this gene profile revealed a unique two-way response, where the antiviral genes can mediate the disease course to mild, contrarily the increased expression of the other gene set might act as pointers of severe disease course. Further, we explored the hematologic parameters from the complete blood count (CBC), which suggests that lymphocytes (low) and neutrophils (high) might serve as an early predictor of prognosis in dengue infection. Collectively, our findings give insights into the foundation for further investigation of the early host response using the RNA isolated from dengue patients' serum samples and opens the door for careful monitoring of the early clinical and transcriptome profiles for management of the dengue patients.

Uncovering the Hidden Threat: A Case Report of Suspected Dengue Fever in Armenia

Dengue is a viral infection transmitted by mosquitoes that causes fever, headache, joint pain, nausea, vomiting, and pain behind the eyes. In severe cases, it can progress to dengue hemorrhagic fever and dengue shock syndrome, which can be life-threatening. Armenia has not reported a single case of dengue to date and is non-endemic for this disease. However, it has been found that the vector of the disease, Aedes albopictus, is present in Armenia since 2016. The aim of this report is to present the imported case of suspected dengue hemorrhagic fever. A 23-year-old female who was admitted to the University Hospital experienced symptoms of general weakness, fever, joint pain, and chills after her return from Bali and had a three-day febrile period. A thorough examination revealed mosquito bites on her skin. On the fourth day of hospitalization, the patient's condition deteriorated. She started experiencing vaginal bleeding. On the same day, the patient noted a small petechiae rash sized 1-2 mm in diameter in the upper and lower extremities. The patient deteriorated, with progressive leukopenia and thrombocytopenia, and hypertransaminasemia. Screening tests for HIV and hepatitis A, B, C, and E were performed, and the results showed that the anti-hepatitis C antibody was positive, while the hepatitis C virus polymerase chain reaction was negative. The case was reported to the National Center for Disease Control and Prevention as an imported case of hemorrhagic fever. Unfortunately, no lab test was available there for confirmation of the diagnosis. The patient received IV infusion and symptomatic treatment. Her condition improved, and upon discharge, she was in a state of recovery. This case report highlights the importance of early diagnosis and appropriate treatment for hemorrhagic fevers, particularly dengue fever. The unavailability of diagnostic kits for dengue in Armenia highlights the need to invest in improving their availability. It also emphasizes the importance of maintaining dengue surveillance in non-endemic nations and carefully evaluating and monitoring febrile patients who have returned from dengue-endemic countries.

A Critical Observation on the Design and Development of Reported Peptide Inhibitors of DENV NS2B-NS3 Protease in the Last Two Decades

Dengue is one of the neglected tropical diseases, which remains a reason for concern as cases seem to rise every year. The failure of the only dengue vaccine, Dengvaxia®, has made the problem more severe and humanity has no immediate respite from this global burden. Dengue virus (DENV) NS2B-NS3 protease is an attractive target partly due to its role in polyprotein processing. Also, since it is among the most conserved domains in the viral genome, it could produce a broad scope of opportunities toward antiviral drug discovery in general. This review has made a detailed analysis of each case of the design and development of peptide inhibitors against DENV NS2B-NS3 protease in the last two decades. Also, we have discussed the reasons attributed to their inhibitory activity, and wherever possible, we have highlighted the concerns raised, challenges met, and suggestions to improve the inhibitory activity. Thus, we attempt to take the readers through the designing and development of reported peptide inhibitors and gain insight from these developments, which could further contribute toward strategizing the designing and development of peptide inhibitors of DENV protease with improved properties in the coming future.

A short survey of dengue protease inhibitor development in the past 6 years (2015-2020) with an emphasis on similarities between DENV and SARS-CoV-2 proteases

Dengue remains a disease of significant concern, responsible for nearly half of all arthropod-borne disease cases across the globe. Due to the lack of potent and targeted therapeutics, palliative treatment and the adoption of preventive measures remain the only available options. Compounding the problem further, the failure of the only dengue vaccine, Dengvaxia®, also delivered a significant blow to any hopes for the treatment of dengue fever. However, the success of Human Immuno-deficiency Virus (HIV) and Hepatitis C Virus (HCV) protease inhibitors in the past have continued to encourage researchers to investigate other viral protease targets. Dengue virus (DENV) NS2B-NS3 protease is an attractive target partly due to its role in polyprotein processing and also for being the most conserved domain in the viral genome. During the early days of the COVID-19 pandemic, a few cases of Dengue-COVID 19 co-infection were reported. In this review, we compared the substrate-peptide residue preferences and the residues lining the sub-pockets of the proteases of these two viruses and analyzed the significance of this similarity. Also, we attempted to abridge the developments in anti-dengue drug discovery in the last six years (2015-2020), focusing on critical discoveries that influenced the research.

Dengue outbreak 2019: clinical and laboratory profiles of dengue virus infection in Dhaka city

Background

Dengue fever has been one of the most common mosquito-transmitted diseases in the world, affecting more than 128 countries in both tropical and subtropical regions. Bangladesh has been sufferring from dengue outbreaks almost annually since 2000, and in 2019, Bangladesh faced the worst outbreak of dengue to date. This study aimed to provide clinical and biochemical profiles of Bangladesh's dengue-infected patients.

Methods

This cross-sectional study was conducted from August through December 2019 in three tertiary private hospitals in Dhaka, Bangladesh. We collected information on demographic data, clinical characteristics, and laboratory profiles for 542 confirmed hospitalized acute dengue cases using a structured questionnaire.

Results

The average age of the enrolled patients was 26.15 years, and about 50% of patients belonged to the age group of 20–40 years. The most frequent among the prevalent clinical symptoms were fever (93.1%), abdominal pain (29.5%), skin rash (25.3%), and diarrhea (19.7%). 316 patients had some complications, such as breathing problems (41.4%), pleural effusion (38.9%), gum bleeding (11.1%), etc. More than 90% of the patients showed seropositivity for the DENV-NS1 antigen.

Conclusions

Over the last couple of years, dengue fever has become a major health issue for Bangladesh. To reduce the burden of this disease, timely diagnosis and prompt treatment are necessary. This analysis thus yields the clinical features, laboratory profiles, and seropositivity test results of dengue patients from Bangladesh. The research results may help clinicians understand the circumstantial diagnosis of dengue patients and facilitate early intervention.

Genome Sequence of a Dengue Virus Serotype 2 Strain Identified during the 2019 Outbreak in Bangladesh

A nearly complete genome sequence of a dengue virus serotype 2 strain detected in the serum of a patient in 2019 during the largest outbreak of dengue fever in Bangladesh is reported.

A nearly complete genome sequence of a dengue virus serotype 2 strain detected in the serum of a patient in 2019 during the largest outbreak of dengue fever in Bangladesh is reported.

Bayesian spatial survival modelling for dengue fever in Makassar, Indonesia

OBJECTIVE

To understand the spatial pattern of dengue fever (DF) patients' survival and investigated factors influencing DF patients' survival.

METHOD

A Bayesian spatial survival method via a conditional autoregressive approach was used to analyze the factors that influence DF patients' survival in 14 sub-districts from January 2015 to May 2017 in Makassar city, Indonesia. Bayesian spatial and a non-spatial model were compared by using deviance information criterion.

RESULTS

The spatial model was more suitable than a non-spatial model. Under the Bayesian spatial model, there was a substantive relationship between age, grade and DF patients' survival time.

CONCLUSIONS

The relative risk map and related factors of DF patients' survival can indicate the health policy makers to give special attention to the high risk areas in order to faster and more targeted treatment.

Phylogenetic Characterization of Arboviruses in Patients Suffering from Acute Fever in Rondônia, Brazil

The purpose of the study was to classify, through phylogenetic analyses, the main arboviruses that have been isolated in the metropolitan region of Porto Velho, Rondônia, Brazil. Serum samples from patients with symptoms suggesting arboviruses were collected and tested by One Step RT-qPCR for Zika, Dengue (serotypes 1–4), Chikungunya, Mayaro and Oropouche viruses. Positive samples were amplified by conventional PCR and sequenced utilizing the Sanger method. The obtained sequences were aligned, and an evolutionary analysis was carried out using Bayesian inference. A total of 308 samples were tested. Of this total, 20 had a detectable viral load for Dengue, being detected DENV1 (18/20), co-infection DENV1 and DENV2 (1/20) and DENV4 (1/20). For Dengue serotype 3 and for the CHIKV, ZIKV, MAYV and OROV viruses, no individuals with a detectable viral load were found. A total of 9 of these samples were magnified by conventional PCR for sequencing. Of these, 6 were successfully sequenced and, according to the evolutionary profile, 5 corresponded to serotype DENV-1 genotype V, and 1 to serotype DENV-4 genotype II. In the study, we demonstrate co-circulation of the DENV-1 genotype V and the DENV-4 genotype II. Co-circulation of several DENV serotypes in the same city poses a risk to the population and is correlated with the increase of the most severe forms of the disease. Similarly, co-circulation of genetically distinct DENV and the occurrence of simultaneous infections can affect recombination events and lead to the emergence of more virulent isolates.

Modeling the effect of temperature on dengue virus transmission with periodic delay differential equations

Dengue fever is a re-emergent mosquito-borne disease, which prevails in tropical and subtropical regions, mainly in urban and peri-urban areas. Its incidence has increased fourfold since 1970, and dengue fever has become the most prevalent mosquito-borne disease in humans now. In order to study the effect of temperature on the dengue virus transmission, we formulate a dengue virus transmission model with maturation delay for mosquito production and seasonality. The basic reproduction number $\mathbb{R}_0$ of the model is computed, and results suggest that the dengue fever will die out if $\mathbb{R}_0$ < 1, and there exists at least one positive periodic solution and the disease will persist if $\mathbb{R}_0$ > 1. Theoretical results are applied to the outbreak of dengue fever in Guangdong province, China. Simulations reveal that the temperature change causes the periodic oscillations of dengue fever cases, which is good accordance with the reported cases of dengue fever in Guangdong province. Our study contributes to a better understanding of dengue virus transmission dynamics and proves beneficial in preventing and controlling of dengue fever.

Dengue hemorrhagic fever - A systemic literature review of current perspectives on pathogenesis, prevention and control

BACKGROUND

Dengue is an arboviral disease caused by dengue virus. Symptomatic dengue infection causes a wide range of clinical manifestations, from mild dengue fever (DF) to potentially fatal disease, such as dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS). We conducted a literature review to analyze the risks of DHF and current perspectives for DHF prevention and control.

METHODS

According to the PRISMA guidelines, the references were selected from PubMed, Web of Science and Google Scholar database using search strings containing a combination of terms that included dengue hemorrhagic fever, pathogenesis, prevention and control. Quality of references were evaluated by independent reviewers.

RESULTS

DHF was first reported in the Philippines in 1953 and further transmitted to the countries in the region of South-East Asia and Western Pacific. Plasma leakages is the main pathophysiological hallmark that distinguishes DHF from DF. Severe plasma leakage can result in hypovolemic shock. Various factors are thought to impact disease presentation and severity. Virus virulence, preexisting dengue antibodies, immune dysregulation, lipid change and host genetic susceptibility are factors reported to be correlated with the development of DHF. However, the exact reasons and mechanisms that triggers DHF remains controversial. Currently, no specific drugs and licensed vaccines are available to treat dengue disease in any of its clinical presentations.

CONCLUSION

This study concludes that antibody-dependent enhancement, cytokine dysregulation and variation of lipid profiles are correlated with DHF occurrence. Prompt diagnosis, appropriate treatment, active and continuous surveillance of cases and vectors are the essential determinants for dengue prevention and control.

Upregulation of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in renal tissue in severe dengue in humans: Effects on endothelial activation/dysfunction

INTRODUCTION

Dengue is an important mosquito-borne disease in tropical and subtropical regions. Adhesion molecules have not been systematically characterized in the renal tissue of patients with severe dengue (SD). The objective of this study was to detect viral antigens in samples from patients that evolved with SD, correlating with the expression of ICAM-1, VCAM-1, VE-cadherin, and E-selectin to contribute to a better understanding of the pathophysiology of SD.

METHODS

Kidney specimens from patients with SD were selected according to clinical and laboratorial data and submitted to histological and immunohistochemistry analysis. A semiquantitative evaluation was performed considering positive immunostaining in 20 glomeruli.

RESULTS

Viral antigens were mainly detected in distal tubules. The intense immunostaining of VCAM-1 and ICAM-1 was observed. The expression of E-selectin was discrete, and VE-cadherin expression varied from mild to moderate. VCAM-1 was slightly intense in the glomerular capsule; the expression of ICAM-1 was diffuse. E-selectin was diffuse, and VE-cadherin varied from mild to moderate. The most frequent histological findings were glomerular congestion, mild glomerulitis, acute renal injury, and glomerular atrophy.

CONCLUSIONS

The results appear to demonstrate an imbalance between vascular endothelial permeability regulating events in renal lesions in SD. The increase in the expression of ICAM-1 and VCAM-1 is an in-situ indicator of higher permeability with a consequent influx of cells favoring the inflammation of the endothelium. These molecules are important in the pathophysiology of the disease and provide the possibility of developing new markers for the evaluation, clinical follow-up, and therapeutic response of patients with SD.

Mathematical analysis of the role of hospitalization/isolation in controlling the spread of Zika fever

The Zika virus is transmitted to humans primarily through Aedes mosquitoes and through sexual contact. It is documented that the virus can be transmitted to newborn babies from their mothers. We consider a deterministic model for the transmission dynamics of the Zika virus infectious disease that spreads in, both humans and vectors, through horizontal and vertical transmission. The total populations of both humans and mosquitoes are assumed to be constant. Our models consist of a system of eight differential equations describing the human and vector populations during the different stages of the disease. We have included the hospitalization/isolation class in our model to see the effect of the controlling strategy. We determine the expression for the basic reproductive number R0 in terms of horizontal as well as vertical disease transmission rates. An in-depth stability analysis of the model is performed, and it is consequently shown, that the model has a globally asymptotically stable disease-free equilibrium when the basic reproduction number R0 < 1. It is also shown that when R0 > 1, there exists a unique endemic equilibrium. We showed that the endemic equilibrium point is globally asymptotically stable when it exists. We were able to prove this result in a reduced model. Furthermore, we conducted an uncertainty and sensitivity analysis to recognize the impact of crucial model parameters on R0. The uncertainty analysis yields an estimated value of the basic reproductive number R0 = 1.54. Assuming infection prevalence in the population under constant control, optimal control theory is used to devise an optimal hospitalization/isolation control strategy for the model. The impact of isolation on the number of infected individuals and the accumulated cost is assessed and compared with the constant control case.

HLA-directed bioinformatics approach for genome-wide mapping of dengue CTL epitopes

Aim: In silico approach was used to predict cytotoxic T lymphocyte (CTL) epitopes from the proteome of all four dengue serotypes. Methods: The immune epitope database analysis resource was used to analyze the CTL epitopes of dengue serotypes. The prediction of epitopes was done against nine high frequency HLA class I alleles occurring worldwide. Results: A total of 2784 epitopes were predicted from all four dengue virus proteomes. Immune epitope database analysis resource tool predicted 202 epitopes as positive for immunogenecity. A total of 39 of 257 consensus epitopes predicted were present in all four serotypes. This study identified nine new class I-restricted epitopes. Conclusion: Mapping of these potentially immunogenic dengue epitopes paves the way for future investigation of their utility as vaccine candidates to prevent or treat dengue virus infections.

Acute Renal Failure Adversely Affects Survival in Pediatric Dengue Infection

Aims

Dengue is currently one of the most important mosquito-borne viral infections. Acute renal failure (ARF) is a serious complication among children suffering from dengue infection.

Subjects and Methods

A retrospective cohort review of baseline characteristics, disease outcomes, and risk factors of dengue-infected patients, with and without renal failure (RF), were compared.

Results

Among 97 children with dengue, 13.4% had RF (estimated glomerular filtration rate <60 ml/min/1.73 m²) at presentation. In comparison to all children (100%) of RF cohort, only 32% children of non-RF cohort (P < 0.0001) were suffering either from dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS). The 7-day survival rate was 61.5% (8/13) among RF group as compared to 96.4% (81/84) in non-RF group (P < 0.001). When a fraction of patients who needed vasopressor support were significantly higher in RF cohort (70% vs. 14% for RF and non-RF, respectively, P < 0.001), requirement of mechanical ventilation (15% vs. 11%, P = 0.67) was comparable in both cohorts.

Conclusions

DHF/DSS is an independent risk factor for the development of ARF in patients with dengue infection. Mortality rate is high once RF develops in these children.

Clinical and Laboratory Diagnosis of Dengue Virus Infection

Infection with any of the 4 dengue virus serotypes results in a diverse range of symptoms, from mild undifferentiated fever to life-threatening hemorrhagic fever and shock. Given that dengue virus infection elicits such a broad range of clinical symptoms, early and accurate laboratory diagnosis is essential for appropriate patient management. Virus detection and serological conversion have been the main targets of diagnostic assessment for many years, however cross-reactivity of antibody responses among the flaviviruses has been a confounding issue in providing a differential diagnosis. Furthermore, there is no single, definitive diagnostic biomarker that is present across the entire period of patient presentation, particularly in those experiencing a secondary dengue infection. Nevertheless, the development and commercialization of point-of-care combination tests capable of detecting markers of infection present during different stages of infection (viral nonstructural protein 1 and immunoglobulin M) has greatly simplified laboratory-based dengue diagnosis. Despite these advances, significant challenges remain in the clinical management of dengue-infected patients, especially in the absence of reliable biomarkers that provide an effective prognostic indicator of severe disease progression. This review briefly summarizes some of the complexities and issues surrounding clinical dengue diagnosis and the laboratory diagnostic options currently available.

Implication of vaccination against dengue for Zika outbreak

Zika virus co-circulates with dengue in tropical and sub-tropical regions. Cases of co-infection by dengue and Zika have been reported, the implication of this co-infection for an integrated intervention program for controlling both dengue and Zika must be addressed urgently. Here, we formulate a mathematical model to describe the transmission dynamics of co-infection of dengue and Zika with particular focus on the effects of Zika outbreak by vaccination against dengue among human hosts. Our analysis determines specific conditions under which vaccination against dengue can significantly increase the Zika outbreak peak, and speed up the Zika outbreak peak timing. Our results call for further study about the co-infection to direct an integrated control to balance the benefits for dengue control and the damages of Zika outbreak.

Modelling weekly vector control against Dengue in the Guangdong Province of China

We develop a mathematical model to closely mimic the integrated program of impulsive vector control (every Friday afternoon since the initiation of the program) and continuous patient treatment and isolation implemented in the Guangdong Province of China during its 2014 dengue outbreak. We fitted the data of accumulated infections and used the parameterized model to carry out a retrospective analysis to estimate the basic reproduction number 1.7425 (95% CI 1.4443-2.0408), the control reproduction number 0.1709, and the mosquito-killing ratios 0.1978, 0.2987, 0.6158 and 0.5571 on October 3, 10, 17 and 24, respectively. This suggests that integrated intervention is highly effective in controlling the dengue outbreak. We also simulated outbreak outcomes under different variations of the implemented interventions. We showed that skipping one Friday for vector control would not result in raising the control reproduction number to the threshold value 1 but would lead to significant increase in the accumulated infections at the end of the outbreak. The findings indicate that quick and persistent impulsive implementation of vector control result in an effective reduction in the control reproduction number and hence lead to significant decline of new infections.

High-throughput screening for the identification of small-molecule inhibitors of the flaviviral protease

The mosquito-borne dengue virus serotypes 1-4 (DENV1-4) and West Nile virus (WNV) cause serious illnesses worldwide associated with considerable morbidity and mortality. According to the World Health Organization (WHO) estimates, there are about 390 million infections every year leading to ∼500,000 dengue haemorrhagic fever (DHF) cases and ∼25,000 deaths, mostly among children. Antiviral therapies could reduce the morbidity and mortality associated with flaviviral infections, but currently there are no drugs available for treatment. In this study, a high-throughput screening assay for the Dengue protease was employed to screen ∼120,000 small molecule compounds for identification of inhibitors. Eight of these inhibitors have been extensively analyzed for inhibition of the viral protease in vitro and cell-based viral replication using Renilla luciferase reporter replicon, infectivity (plaque) and cytotoxicity assays. Three of these compounds were identified as potent inhibitors of DENV and WNV proteases, and viral replication of DENV2 replicon and infectious RNA. Fluorescence quenching, kinetic analysis and molecular modeling of these inhibitors into the structure of NS2B-NS3 protease suggest a mode of inhibition for three compounds that they bind to the substrate binding pocket.

The Spread of Dengue in an Endemic Urban Milieu--The Case of Delhi, India

BACKGROUND

Dengue is a major international public health concern, one of the most important arthropod-borne diseases. More than 3.5 billion people are at risk of dengue infection and there are an estimated 390 million dengue infections annually. This prolific increase has been connected to societal changes such as population growth and increasing urbanization generating intense agglomeration leading to proliferation of synanthropic mosquito species. Quantifying the spatio-temporal epidemiology of dengue in large cities within the context of a Geographic Information System is a first step in the identification of socio-economic risk factors.

METHODOLOGY/PRINCIPAL FINDINGS

This Project has been approved by the ethical committee of Institut Pasteur. Data has been anonymized and de-identified prior to geolocalisation and analysis. A GIS was developed for Delhi, enabling typological characterization of the urban environment. Dengue cases identified in the Delhi surveillance system from 2008 to 2010 were collated, localised and embedded within this GIS. The spatio-temporal distribution of dengue cases and extent of clustering were analyzed. Increasing distance from the forest in Delhi reduced the risk of occurrence of a dengue case. Proximity to a hospital did not increase risk of a notified dengue case. Overall, there was high heterogeneity in incidence rate within areas with the same socio-economical profiles and substantial inter-annual variability. Dengue affected the poorest areas with high density of humans, but rich areas were also found to be infected, potentially because of their central location with respect to the daily mobility network of Delhi. Dengue cases were highly clustered in space and there was a strong relationship between the time of introduction of the virus and subsequent cluster size. At a larger scale, earlier introduction predicted the total number of cases.

CONCLUSIONS/SIGNIFICANCE

DENV epidemiology within Delhi has a forest fire signature. The stochastic nature of this invasion process likely smothers any detectable socio-economic risk factors. However, the significant finding that the size of the dengue case cluster depends on the timing of its emergence emphasizes the need for early case detection and implementation of effective mosquito control. A better understanding of the role of population mobility in contributing to dengue risk could also help focus control on areas at particular risk of dengue virus importation.

Binding specificity of polypeptide substrates in NS2B/NS3pro serine protease of dengue virus type 2: A molecular dynamics Study

The pathogenic dengue virus (DV) is a growing global threat, particularly in South East Asia, for which there is no specific treatment available. The virus possesses a two-component (NS2B/NS3) serine protease that cleaves the viral precursor proteins. Here, we performed molecular dynamics simulations of the NS2B/NS3 protease complexes with six peptide substrates (capsid, intNS3, 2A/2B, 4B/5, 3/4A and 2B/3 containing the proteolytic site between P(1) and P(1)' subsites) of DV type 2 to compare the specificity of the protein-substrate binding recognition. Although all substrates were in the active conformation for cleavage reaction by NS2B/NS3 protease, their binding strength was somewhat different. The simulated results of intermolecular hydrogen bonds and decomposition energies suggested that among the ten substrate residues (P(5)-P(5)') the P(1) and P(2) subsites play a major role in the binding with the focused protease. The arginine residue at these two subsites was found to be specific preferential binding at the active site with a stabilization energy of <-10 kcal mol(-1). Besides, the P(3), P(1)', P(2)' and P(4)' subsites showed a less contribution in binding interaction (<-2 kcal mol(-1)). The catalytic water was detected nearby the carbonyl oxygen of the P(1) reacting center of the capsid, intNS3, 2A/2B and 4B/5 peptides. These results led to the order of absolute binding free energy (ΔGbind) between these substrates and the NS2B/NS3 protease ranked as capsid>intNS3>2A/2B>4B/5>3/4A>2B/3 in a relative correspondence with previous experimentally derived values.

Distribution of yellow fever vectors in Northwestern and Western Provinces, Zambia

OBJECTIVE

To determine the distribution of yellow fever (YF) vectors species in Northwestern and Western of Zambia, which sampled mosquitoes inside and outside houses in rural, urban, peri-urban and forest areas.

METHODS

Back-pack aspirators spray catches and CDC light traps collected adult mosquitoes including 405 Aedes, 518 Anopheles, 471 Culex and 71 Mansonia. Morphological vector identification and PCR viral determination were done at a WHO Regional Reference Centre (Institute Pasteur Dakar), Senegal.

RESULTS

The two main YF vectors were Aedes (Stegomyia) aegypti (Ae. aegypti) and Aedes (Stegomyia) africanus. The first was collected in peri-urban areas and the later was in forest areas, both sparsely distributed in Northwestern Province, where the 0.43 Breteau and 1.92 container indexes, respectively implied low risk to YF. Aedes (Aedimorphus) mutilus; Aedes (Aedimorphus) minutus and Aedes (Finlaya) wellmani were also found in Northwestern, not in Western Province. No Aedes were collected from rural peri-domestic areas. Significantly more Aedes species (90.7%, n=398) than Anopheles (9.1%, n=40) were collected in forest areas (P<0.001) or Culex species (0.2%, n=2) (P<0.001). Ae. aegypti was found only in a discarded container but not in flower pots, old tyres, plant axils, discarded shallow wells, disused container bottles and canoes inspected.

CONCLUSIONS

Ae. aegypti and Aedes africanus YF vectors were found in the study sites in the Northwestern Province of Zambia, where densities were low and distribution was sparse. The low Breteau index suggests low risk of YF in the Northwestern Province. The presence of Aedes in Northwestern Province and its absence in the Western Province could be due to differing ecological factors in the sampled areas. Universal coverage of vector control interventions could help to reduce YF vector population and the risk to arthropod-borne virus infections.

Estimating the basic reproduction number for single-strain dengue fever epidemics

Background

Dengue, an infectious tropical disease, has recently emerged as one of the most important mosquito-borne viral diseases in the world. We perform a retrospective analysis of the 2011 dengue fever epidemic in Pakistan in order to assess the transmissibility of the disease. We obtain estimates of the basic reproduction number R₀ from epidemic data using different methodologies applied to different epidemic models in order to evaluate the robustness of our estimate.

Results

We first estimate model parameters by fitting a deterministic ODE vector-host model for the transmission dynamics of single-strain dengue to the epidemic data, using both a basic ordinary least squares (OLS) as well as a generalized least squares (GLS) scheme. Moreover, we perform the same analysis for a direct-transmission ODE model, thereby allowing us to compare our results across different models. In addition, we formulate a direct-transmission stochastic model for the transmission dynamics of dengue and obtain parameter estimates for the stochastic model using Markov chain Monte Carlo (MCMC) methods. In each of the cases we have considered, the estimate for the basic reproduction number R₀ is initially greater than unity leading to an epidemic outbreak. However, control measures implemented several weeks after the initial outbreak successfully reduce R₀ to less than unity, thus resulting in disease elimination. Furthermore, it is observed that there is strong agreement in our estimates for the pre-control value of R₀, both across different methodologies as well across different models. However, there are also significant differences between our estimates for the post-control value of the basic reproduction number across the two different models.

Conclusion

In conclusion, we have obtained robust estimates for the value of the basic reproduction number R₀ associated with the 2011 dengue fever epidemic before the implementation of public health control measures. Furthermore, we have shown that there is close agreement between our estimates for the post-control value of R₀ across the different methodologies. Nevertheless, there are also significant differences between the estimates for the post-control value of R₀ across the two different models.

Seroprevalence of dengue in the general population of Hong Kong

OBJECTIVES

To assess the extent of dengue virus exposure in the population.

METHODS

In this seroepidemiological study, 685 blood samples were collected (from April 2007 to July 2009) from two subject groups: (i) 344 samples from anonymous blood donors of the Hong Kong Red Cross and (ii) 341 samples from healthy volunteers recruited from a university, a community centre and a hospital. Demographic information and travel history were collected for the second subject group. All blood samples were subjected to the PanBio Dengue IgG Indirect ELISA.

RESULTS

Anti-dengue virus IgG was detected in 1.6% of the blood samples. Individuals who visited countries in Southeast Asia in the past year were significantly associated with seropositivity (P = 0.03, OR 5.38, CI 1.13-25.54).

CONCLUSIONS

The overall dengue seroprevalence was 1.6%, and visit to Southeast Asia was the only independent predictor for seropositivity. Although the current situation is not alarming, frequent travel, presence of mosquito vector and emergence of local cases suggest that the risk of dengue virus infection within the local community cannot be overlooked, and continuous vigilance is warranted.

A simple periodic-forced model for dengue fitted to incidence data in Singapore

Dengue is the world's major arbovirosis and therefore an important public health concern in endemic areas. The availability of weekly reports of dengue cases in Singapore offers the opportunity to analyze the transmission dynamics and the impact of vector control strategies. Based on a previous model studying the impact of vector control strategies in Singapore during the 2005 outbreak, a simple vector-host model accounting for seasonal fluctuation in vector density was developed to estimate the parameters governing the vector population dynamics using dengue fever incidence data from August 2003 to December 2007. The impact of vector control, which consisted principally of a systematic removal of actual and potential breeding sites during a six-week period in 2005, was also investigated. Although our approach does not account for the complex life cycle of the vector, the good fit between data and model outputs showed that the impact of seasonality on the transmission dynamics is highly important. Moreover, the periodic fluctuations of the vector population were found in phase with temperature variations, suggesting a strong climate effect on the vector density and, in turn, on the transmission dynamics.

A review of dengue as an emerging disease in Pakistan

The presence of dengue virus has been detected using neutralization and haemagglutination inhibition antibodies in local populations in Pakistan since the 1960s. However, the first epidemic was not reported until 1994. This was followed by some cases in 1995, but the disease was confined to the port city of Karachi. Since 2006, dengue epidemics have occurred every year and the range has extended to most cities in Pakistan. Dengue now affects thousands of people and has caused hundreds of deaths. It has become a major health problem in Pakistan, and it is likely to become an even greater health problem in the coming years. This review gives an insight into the dengue situation from the early 1960s to the most recent epidemics in Pakistan, and also describes the primary vector of this disease (Aedes aegypti) in Pakistan. As such, it provides the first comprehensive review of the emergence of this important public health problem.

Gamma interferon (IFN-γ) receptor restricts systemic dengue virus replication and prevents paralysis in IFN-α/β receptor-deficient mice

We previously reported that mice lacking alpha/beta and gamma interferon receptors (IFN-α/βR and -γR) uniformly exhibit paralysis following infection with the dengue virus (DENV) clinical isolate PL046, while only a subset of mice lacking the IFN-γR alone and virtually no mice lacking the IFN-α/βR alone develop paralysis. Here, using a mouse-passaged variant of PL046, strain S221, we show that in the absence of the IFN-α/βR, signaling through the IFN-γR confers approximately 140-fold greater resistance against systemic vascular leakage-associated dengue disease and virtually complete protection from dengue-induced paralysis. Viral replication in the spleen was assessed by immunohistochemistry and flow cytometry, which revealed a reduction in the number of infected cells due to IFN-γR signaling by 2 days after infection, coincident with elevated levels of IFN-γ in the spleen and serum. By 4 days after infection, IFN-γR signaling was found to restrict DENV replication systemically. Clearance of DENV, on the other hand, occurred in the absence of IFN-γR, except in the central nervous system (CNS) (brain and spinal cord), where clearance relied on IFN-γ from CD8(+) T cells. These results demonstrate the roles of IFN-γR signaling in protection from initial systemic and subsequent CNS disease following DENV infection and demonstrate the importance of CD8(+) T cells in preventing DENV-induced CNS disease.

Dynamic epidemiological models for dengue transmission: a systematic review of structural approaches

Dengue is a vector-borne disease recognized as the major arbovirose with four immunologically distant dengue serotypes coexisting in many endemic areas. Several mathematical models have been developed to understand the transmission dynamics of dengue, including the role of cross-reactive antibodies for the four different dengue serotypes. We aimed to review deterministic models of dengue transmission, in order to summarize the evolution of insights for, and provided by, such models, and to identify important characteristics for future model development. We identified relevant publications using PubMed and ISI Web of Knowledge, focusing on mathematical deterministic models of dengue transmission. Model assumptions were systematically extracted from each reviewed model structure, and were linked with their underlying epidemiological concepts. After defining common terms in vector-borne disease modelling, we generally categorised fourty-two published models of interest into single serotype and multiserotype models. The multi-serotype models assumed either vector-host or direct host-to-host transmission (ignoring the vector component). For each approach, we discussed the underlying structural and parameter assumptions, threshold behaviour and the projected impact of interventions. In view of the expected availability of dengue vaccines, modelling approaches will increasingly focus on the effectiveness and cost-effectiveness of vaccination options. For this purpose, the level of representation of the vector and host populations seems pivotal. Since vector-host transmission models would be required for projections of combined vaccination and vector control interventions, we advocate their use as most relevant to advice health policy in the future. The limited understanding of the factors which influence dengue transmission as well as limited data availability remain important concerns when applying dengue models to real-world decision problems.

Event history analysis of dengue fever epidemic and inter-epidemic spells in Barbados, Brazil, and Thailand

OBJECTIVE

This study investigated meteorological and demographic factors affecting the length of dengue fever epidemics and the length of time between epidemics in Barbados, Brazil, and Thailand.

METHODS

Region-specific meteorological and demographic data were collected for 104 sites from public sources. Fixed effects piecewise logistic event history analysis was used to quantify the effects of time-varying covariates on the duration of inter-epidemic spells and for the duration of epidemics.

RESULTS

Mean monthly temperature was the most important factor affecting the duration of both inter-epidemic spells (β=0.543; confidence interval (CI) 0.4954, 0.5906) and epidemic spells (β=-0.648; CI -0.7553, -0.5405). Drought conditions increased the time between epidemics. Increased temperature hastened the onset of an epidemic, and during an epidemic, higher mean temperature increased the duration of the epidemic.

CONCLUSIONS

By using a duration analysis, this study offers a novel approach for investigating the dynamics of dengue fever epidemiology. Furthermore, these results offer new insights into prior findings of a correlation between temperature and the geographic range and vector efficiency of dengue fever.

Spectrum of imported infectious diseases among children and adolescents returning from the tropics and subtropics

BACKGROUND

About 50 million people travel each year from industrialized countries to destinations in the tropics and subtropics. Among them, there are more than 2 million minors traveling. Although their number is increasing constantly, data on health risks during travel are limited.

METHODS

This study analyzed demographic, travel, and clinical data of 890 travelers of age <20 years presenting at the outpatient travel clinic of the University of Munich between 1999 and 2009 after returning from the tropics and subtropics.

RESULTS

Most (87%) of these young travelers were born in Germany. Among them, the main travel destination was Africa (46%), followed by Asia (35%) and Latin America (19%). The most frequent syndrome groups were acute diarrhea (25%, especially in age 0-4 y), dermatologic disorders (21%, especially in age 0-9 y), febrile/systemic diseases (20%), respiratory disorders (8%), chronic diarrhea (5%), and genitourinary disorders (3%). The 10 most frequent diagnosed infectious diseases were giardiasis (8%), schistosomiasis (4%), superinfected insect bites (4%), Campylobacter enteritis (4%), Salmonella enteritis (4%), cutaneous larva migrans (3%), amebiasis (3%), dengue fever (2%), mononucleosis (2%), and malaria (2%). The relative risk (RR) for acquiring any infectious disease during travel was highest in Central, West, and East Africa, followed by South America, South Asia, and Southeast Asia.

CONCLUSIONS

Age of young travelers and destination of travel were the most important variables being strongly correlated with the risk for acquiring infectious diseases in the tropics and subtropics. The highest risk was carried by very young travelers and those staying in sub-Saharan Africa (except Southern Africa).

The laboratorial diagnosis of dengue: applications and implications

The diagnosis of infection by the dengue virus relies, in most cases, on the clinical judgment of the patient, since only a few major centers have clinical laboratories that offer diagnostic tests to confirm the clinical impressions of an infection. At present, routine laboratory diagnosis is done by different kinds of testing. Among them are the methods of serological research, virus isolation, detection of viral antigens, and detection of viral genomes. The continued development of diagnostic tests, which are cheap, sensitive, specific, easy to perform, and capable of giving early diagnosis of the dengue virus infection is still a need. There are also other obstacles that are not specifically related to the technological development of diagnostic methods. For instance, infrastructure of the laboratories, the training of personnel, and the capacity of research of these laboratories are still limited in many parts of Brazil and the world, where dengue is endemic. Clinical laboratories, especially the ones that serve regions with a high incidence of dengue, should be aware of all the diagnostic methods available for routine these days, and choose the one that best suit their working conditions and populations served, in order to save lives.

Live-attenuated Tetravalent Dengue Vaccine in Dengue-naïve Children, Adolescents, and Adults in Mexico City: Randomized Controlled Phase 1 Trial of Safety and Immunogenicity

BACKGROUND

Preliminary results in healthy, young US adults showed that a tetravalent, live-attenuated dengue vaccine (TDV) was safe and immunogenic, but no data are available in children.

METHODS

In a multicenter, randomized, controlled, observer-blinded study in the city of Mexico, children aged 2 to 5, 6 to 11, and 12 to 17 years (36 children per age group), and adults (n = 18) aged <45 years received the following: 3 injections of TDV at months 0, 3.5, and 12 (TDV-TDV-TDV), or 1 injection of yellow fever vaccine (YF) at month 0, and 2 injections of TDV at months 3.5 and 12 (YF-TDV-TDV). Adverse events and biologic safety (biochemistry and hematology) were documented. Plaque reduction neutralization test (PRNT50) antibody titers against the TDV parental viruses were measured 28 days after vaccination. Seropositivity was defined as antibody titers ≥10 1/dil.

RESULTS

No vaccine-related serious adverse events, other significant clinical adverse events, or clinically significant trends in biologic safety were observed. Reactogenicity did not increase with successive TDV injections, and mild-to-moderate injection site pain, headache, myalgia, and malaise were most commonly reported (14%-40% after each vaccination). After 3 TDV vaccinations, the seropositivity rate against each dengue serotype was in the range 77% to 92%, compared with 85% to 94% after completion of the YF-TDV-TDV regimen. Of the 2- to 11-year-old participants, 95% were seropositive against ≥3 serotypes after 3 vaccinations.

CONCLUSIONS

A 3-dose TDV regimen had a favorable safety profile in children and adults and elicited neutralizing antibody responses against all 4 serotypes. These findings support the continued development of this vaccine.

Predictors of spontaneous bleeding in patients with acute febrile syndrome from a dengue endemic area

BACKGROUND

Spontaneous bleeding is a common complication of dengue and is associated with an increased mortality.

OBJECTIVE

To evaluate early clinical manifestations and simple laboratory tests as predictors of spontaneous hemorrhage in patients with forms of acute febrile syndrome (AFS) such as dengue from an endemic area.

STUDY DESIGN

A prospective cohort study was performed including 729 non-bleeding AFS patients who were enrolled during the first 4 days of disease. Basal evaluation included anamnesis, physical examination and complete blood cell count. Follow-up was extended at least until the sixth day of disease. Dengue infection was studied with paired serologic tests and viral isolation. Potential predictors of spontaneous bleeding were evaluated with bivariate and multivariate analysis.

RESULTS

Incidence of outcome was not significantly different between the dengue group and those with non-dengue AFS. The tourniquet test was not associated with outcome (p=0.38). In a binomial regression model, the following variables were associated with outcome: age between 12 and 45 years (RR=2.22; 95% CI: 1.25-3.94), rash (RR=1.66; 95% CI: 1.25-2.2), vomiting (RR=1.46; 95% CI: 1.16-1.83), temperature >38 degrees C (RR=2.63; 95% CI: 1.6-4.33), leukocyte count <4500/microL (RR=1.87; 95% CI: 1.19-2.96), and platelet count <90.000/microL (RR=1.8; 95% CI: 1.1-2.94). With these variables a risk score was formulated that showed an area under ROC curve of 70.5% (95% CI: 64.9-76.2) to predict spontaneous bleeding. The score was useful for predicting bleeding in both dengue and non-dengue AFS groups.

CONCLUSION

Some variables evaluated in the first days of disease helped to predict the risk of spontaneous bleeding in patients with dengue and non-dengue AFS.

CT angiography of coronary artery aneurysms: detection, definition, causes, and treatment

OBJECTIVE

This article reviews the predisposing conditions, diagnostic criteria, CT appearances, and potential complications of coronary artery aneurysms.

CONCLUSION

With the increasing use of MDCT to image the coronary arteries, aneurysms will be identified more frequently. Coronary artery aneurysms arise from a variety of causes, with CT appearance, management, and clinical course depending on the cause.

NS3 protease from flavivirus as a target for designing antiviral inhibitors against dengue virus

The development of novel therapeutic agents is essential for combating the increasing number of cases of dengue fever in endemic countries and among a large number of travelers from non-endemic countries. The dengue virus has three structural proteins and seven non-structural (NS) proteins. NS3 is a multifunctional protein with an N-terminal protease domain (NS3pro) that is responsible for proteolytic processing of the viral polyprotein, and a C-terminal region that contains an RNA triphosphatase, RNA helicase and RNA-stimulated NTPase domain that are essential for RNA replication. The serine protease domain of NS3 plays a central role in the replicative cycle of dengue virus. This review discusses the recent structural and biological studies on the NS2B-NS3 protease-helicase and considers the prospects for the development of small molecules as antiviral drugs to target this fascinating, multifunctional protein.

The Role Activity of Complement, TNFα & IL12 in Pathogenesis Dengue Virus

Dengue Virus infection is always found in some part of the world especially South East Asia including Indonesia. The pathogenesis of Dengue Virus infection is still controversial. The aim of this study is to analyze the role complement activity, TNFα & IL12 in Dengue Virus infection especially in pathogenesis of Dengue Virus infection. Cross sectional study had been done since February 2009 in Dr. Soetomo Hospital Surabaya. Blood Sera of Dengue Virus infection were collected from Dengue Fever, and Dengue Hemorrhagic Fever patient who had been care in Paediatric. Dengue patients and time schedule for taking blood sample for examination CH50, TNFα & IL12 as follow: on the first day on admission, the second day, the third day. Study groups of patients as follow: Dengue Fever, 36; Dengue Hemorrhagic Fever grade I, 37; Dengue Hemorrhagic Fever grade II, 10; Dengue Hemorrhagic Fever grade III, 18; Dengue Hemorrhagic Fever grade IV, 6. In this study found that the higher activity complement which lower level CH50 was more identified on Dengue Shock Syndrome and Dengue Hemorrhagic Fever grade III than Dengue Fever cases. A concept of our study was focusing on manifestation of vascular leakage, measurement of complement activity CH50, TNFα & IL12 and clinical manifestation Dengue Hemorrhagic Fever. The examination of TNFα & IL12 in our study supported the role the activity complement. The conclusion are measurement CH50, TNFα & IL12 can be used as a predictive factor of the degree of Dengue Virus infection

Serum levels of interleukin-6, tumor necrosis factor-alpha and interferon-gamma in infants with and without dengue

This study compared the serum levels of IL-6, TNF-alpha and IFN-gamma, in children under 1 year of age with and without dengue. Sera were collected from a total of 41 children living in the Department of Antioquia, Colombia (27 patients with dengue and 14 controls). The results showed higher cytokine levels in children with dengue than without dengue, with statistically significant differences for IL-6 and IFN-gamma. No statistically significant differences were found between clinical forms, although IL-6 and IFN-gamma levels were higher in dengue fever cases than in dengue hemorrhagic fever cases. On the other hand, TNF-alpha levels were higher in dengue hemorrhagic fever than in dengue fever. The levels of IL-6 and TNF-alpha were higher in secondary infection than in primary infection, although IFN-gamma levels were higher in primary infection. These results suggest that IL-6, TNF-alpha and IFN-gamma are involved in dengue infection independently of the clinical form.

Impact of renal failure on the outcome of dengue viral infection

BACKGROUND AND OBJECTIVES

In the 2002 dengue outbreak in Taiwan, some fatal cases had the underlying disease of renal failure (RF). Physicians faced difficulty in diagnosis and treatment of these patients; however, the impacts of RF on the clinical presentations and outcomes of dengue infection have not been reported previously.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A retrospective review was conducted of medical records, clinical presentations, laboratory findings, and underlying diseases for all cases of dengue infection in a medical center. Characteristics and outcomes of dengue-infected patients with and without RF were compared.

RESULTS

From January 2002 through January 2003, 519 dengue-infected patients were enrolled, including 412 patients with classical dengue fever (DF) and 107 patients with dengue hemorrhagic fever (DHF)/dengue shock syndrome (DSS). Twelve patients died in this outbreak, and all had DHF/DSS. Twenty-one (4.0%) patients were defined as being in the RF group. The RF group had a higher mortality rate than non-RF group (28.6 versus 1.2%; P < 0.001). The severity of GFR impairment was associated with higher percentages of DHF/DSS (P = 0.029) and mortality (P < 0.001). Differences in symptoms/signs and laboratory abnormalities between DF and DHF/DSS were significant in the non-RF group but not apparent in the RF group.

CONCLUSIONS

The diagnosis and management of dengue infection among patients with RF must be cautious, because complicated clinical courses with a higher mortality rate were well observed.

Mosquito larvicidal activities of Solanum villosum berry extract against the dengue vector Stegomyia aegypti

Background

Vector control is facing a threat due to the emergence of resistance to synthetic insecticides. Insecticides of botanical origin may serve as suitable alternative biocontrol techniques in the future. Although several plants have been reported for mosquitocidal activity, only a few botanicals have moved from the laboratory to field use, because they are poorly characterized, in most cases active principals are not determined and most of the works are restricted to preliminary screening. Solanum villosum is a common weed distributed in many parts of India with medicinal properties, but the larvicidal activity of this plant has not been reported so far.

Methods

Aqueous and polar/non-polar solvent extract of fresh, mature, green berries of S. villosum was tested against Stegomyia aegypti, a common vector of dengue fever. A phytochemical analysis of chloroform:methanol extract was performed to search for the active toxic ingredient. The lethal concentration was determined (log probit analysis) and compared with Malathion. The chemical nature of the active substance was also evaluated following ultraviolet-visual (UV-Vis) and infrared (IR) analysis.

Results

In a 72 hour bioassay experiment with the aqueous extract, the highest mortality was recorded in 0.5% extract. When the mortality of different solvent extracts was compared, the maximum (p < 0.05) mortality was recorded at a concentration of 50 ppm of chloroform:methanol extract (1:1, v/v). The larvicidal activity was lower when compared with the chemical insecticide, Malathion (p < 0.05). Results of regression analysis revealed that the mortality rate (Y) was positively correlated with the period of exposure (X) and the log probit analysis (95% confidence level) recorded lowest value (5.97 ppm) at 72 hours of exposure. Phytochemical analysis of the chlororm:methanol extract reported the presence of many bioactive phytochemicals. Two toxic compounds were detected having R_f = 0.82 (70% and 73.33% mortality in 24 and 48 hours, respectively) and R_f = 0.95 (40% and 50% mortality in 24 and 48 hours, respectively). IR analysis provided preliminary information about the steroidal nature of the active ingredient.

Conclusion

S. villosum offers promise as potential bio control agent against S. aegypti particularly in its markedly larvicidal effect. The extract or isolated bioactive phytochemical could be used in stagnant water bodies for the control of mosquitoes acting as vector for many communicable diseases.

Finding intervention points in the pathogenesis of Dengue viral infection

We use probabilistic Boolean networks to simulate the pathogenesis of Dengue Hemorraghic Fever (DHF). Based on Chaturvedi's work, the strength of cytokine influences are modeled stochastically as inducement probabilities. We use an aggregated function approach to derive the DHF Infection Model. Two basins of attractors are observed with synchronous updating; the Null Infection cycle attractor shows an expected cross-regulation of Th1 and Th2 cytokines corresponding to the homeostasis of an uninfected person, while the DHF Infection attractor shows the onset of DHF. With asynchronous updating, our model remains valid with clinical comparisons against qualitative changes in signal durations. In order to find intervention points that could prevent DHF we design a genetic algorithm to shift the DHF attractor to the DF attractor basin by using the DF final state as the fitness measure. Our simulation results identify TGF-beta, IL-8 and IL-13 as the intervention points which are consistent with known clinical results to prevent DHF from occurring.