Dengue poses a significant health and economic burden in the WHO South-East Asia Region. Approaches for control need to be aligned with current knowledge on the epidemiology of dengue in the region. Such knowledge will ensure improved targeting of interventions to reduce dengue incidence and its socioeconomic impact. This review was undertaken to describe the contemporary epidemiology of dengue and critically analyse the existing surveillance strategies in the region. Over recent decades, dengue incidence has continued to increase with geographical expansion. The region has now become hyper-endemic for multiple dengue virus serotypes/genotypes. Every epidemic cycle was associated with a change of predominant serotype/genotype and this was often associated with severe disease with intense transmission. Classical larval indices are widely used in vector surveillance and adult mosquito samplings are not implemented as a part of routine surveillance. Further, there is a lack of integration of entomological and disease surveillance systems, often leading to inaction or delays in dengue prevention and control. Disease surveillance does not capture all cases, resulting in under-reporting, and has thus failed to adequately represent the true burden of disease in the region. Possible solutions include incorporating adult mosquito sampling into routine vector surveillance, the establishment of laboratory-based sentinel surveillance, integrated vector and dengue disease surveillance and climate-based early warning systems using available technologies like mobile apps.

Epidemiology and challenges of dengue surveillance in the WHO South-East Asia Region.

Unusual, neurological and severe dengue manifestations during the outbreak in Sri Lanka, 2017.

Dengue induces a spectrum of severity in humans from the milder dengue fever to severe disease, or dengue hemorrhagic fever (DHF). Chymase is a candidate biomarker that may aid dengue prognosis. This prospective study aimed to identify whether warning signs of severe dengue, including hypovolemia and fluid accumulation, were associated with elevated chymase. Serum chymase levels were quantified prospectively and longitudinally in hospitalized pediatric dengue patients in Sri Lanka. Warning signs were determined based on daily clinical assessments, laboratory tests and ultrasound findings. Chymase was significantly elevated during the acute phase of disease in DHF or Severe dengue, defined by either the 1997 or 2009 WHO diagnosis guidelines, and persisted longer in the most severe patients. Chymase levels were higher in patients with narrow pulse pressure and clinical warning signs such as severe leakage, fluid accumulation, pleural effusion, gall-bladder wall thickening and rapid haematocrit rise concurrent with thrombocytopenia. No association between chymase and liver enlargement was observed. This study confirms that serum chymase levels are associated with DHF/Severe dengue disease in hospitalized pediatric patients. Chymase levels correlate with warning signs of vascular dysfunction highlighting the possible functional role of chymase in vascular leakage during dengue.

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Serum chymase levels correlate with severe dengue warning signs and clinical fluid accumulation in hospitalized pediatric patients

Dengue virus (DENV) infection remains a major public health concern in many parts of the world, including Southeast Asia and the Americas Sri Lanka experienced its largest dengue outbreak in 2017 Neurological symptoms associated with DENV infection have increasingly been reported in both children and adults Here, we characterize DENV type 2 (DENV-2) strains, which were isolated from cerebrospinal fluid (CSF) and/or serum of patients with dengue encephalitis Acute serum and CSF samples from each patient were subjected to dengue-specific non-structural protein 1 (NS1) antigen test, IgM and IgG enzyme-linked immunosorbent assay (ELISA), virus isolation, conventional and real-time polymerase chain reaction (PCR), and next-generation sequencing (NGS) Among the 5 dengue encephalitis patients examined, 4 recovered and 1 died DENV-2 strains were isolated from serum and/or CSF samples of 3 patients The highest viral genome levels were detected in the CSF and serum of the patient who succumbed to the illness A phylogenetic tree revealed that the DENV-2 isolates belonged to a new clade of cosmopolitan genotype and were genetically close to strains identified in China, South Korea, Singapore, Malaysia, Thailand, and the Philippines According to the NGS analysis, greater frequencies of nonsynonymous and synonymous mutations per gene were identified in the nonstructural genes The full genomes of serum- and CSF-derived DENV-2 from the same patient shared 997% similarity, indicating that the virus spread across the blood-brain barrier This is the first report to describe neurotropic DENV-2 using whole-genome analysis and to provide the clinical, immunological, and virological characteristics of dengue encephalitis patients during a severe dengue outbreak in Sri Lanka in 2017

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Complete genome analysis and characterization of neurotropic dengue virus 2 cosmopolitan genotype isolated from the cerebrospinal fluid of encephalitis patients.

More than 80,000 dengue cases including 215 deaths were reported nationally in less than 7 months between 2016 and 2017, a fourfold increase in the number of reported cases compared to the average number over 2010–2016. The region of Negombo, located in the Western province, experienced the greatest number of dengue cases in the country and is the focus area of our study, where we aim to capture the spatial-temporal dynamics of dengue transmission. We present a statistical modeling framework to evaluate the spatial-temporal dynamics of the 2016–2017 dengue outbreak in the Negombo region of Sri Lanka as a function of human mobility, land-use, and climate patterns. The analysis was conducted at a 1 km × 1 km spatial resolution and a weekly temporal resolution. Our results indicate human mobility to be a stronger indicator for local outbreak clusters than land-use or climate variables. The minimum daily temperature was identified as the most influential climate variable on dengue cases in the region; while among the set of land-use patterns considered, urban areas were found to be most prone to dengue outbreak, followed by areas with stagnant water and then coastal areas. The results are shown to be robust across spatial resolutions. Our study highlights the potential value of using travel data to target vector control within a region. In addition to illustrating the relative relationship between various potential risk factors for dengue outbreaks, the results of our study can be used to inform where and when new cases of dengue are likely to occur within a region, and thus help more effectively and innovatively, plan for disease surveillance and vector control.

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Modeling the relative role of human mobility, land-use and climate factors on dengue outbreak emergence in Sri Lanka.

Background The outbreak of dengue during 2017 in Sri Lanka is the worst incidence of this mosquito-borne virus infection in the South Asian country since records began. Methods In this retrospective study, up to the end of December 2017 over 185,000 clinical cases were reported from all regions of the island nation. Results This crisis placed an overwhelming burden on Sri Lanka's public health system and also had a significant negative impact on its economy. Conclusions The unsurpassed level of morbidity and mortality has highlighted the pressing need for an effective operational plan to both manage the existing outbreak and to reduce the threat of a future episode of disease. This should involve an integrated nationwide program of vector surveillance and control, tertiary care of severely affected individuals and the implementation of measures to prevent future infectio ns, including widespread vaccination.

The unprecedented magnitude of the 2017 dengue outbreak in Sri Lanka provides lessons for future mosquito-borne infection control and prevention

Pathological features observed in both human and experimental cerebral malaria (ECM) are endothelial dysfunction and changes in blood components. Blood transfusion has been routinely used in patients with severe malarial anemia and can also benefit comatose and acidotic malaria patients. In the present study Plasmodium berghei-infected mice were transfused intraperitoneally with 200 μL of whole blood along with 20 mg/kg of artemether. ECM mice showed severe thrombocytopenia and decreases in hematocrit. Artemether treatment markedly aggravated anemia within 24 h. Whole blood administration significantly prevented further drop in hematocrit and partially restored the platelet count. Increased levels of plasma angiopoietin-2 (Ang-2) remained high 24 h after artemether treatment but returned to normal levels 24 h after blood transfusion, indicating reversal to quiescence. Ang-1 was depleted in ECM mice and levels were not restored by any treatment. Blood transfusion prevented the aggravation of the breakdown of blood brain barrier after artemether treatment and decreased spleen congestion without affecting splenic lymphocyte populations. Critically, blood transfusion resulted in markedly improved survival of mice with ECM (75.9% compared to 50.9% receiving artemether only). These findings indicate that whole blood transfusion can be an effective adjuvant therapy for cerebral malaria.

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Whole blood transfusion improves vascular integrity and increases survival in artemether-treated experimental cerebral malaria.

In Brazil, species of the genus Ramphocelus with the presence of various endoparasites have already been reported. Coccidia have been the parasites most frequently found. All species of this genus have similar habitats and ecological niches, which makes parasite transmission easy. The aim of this study was to diagnose the presence of endoparasites in fecal samples from specimens of Ramphocelus carbo that were caught in the Cazumba-Iracema Extractive Reserve (Cazumba Resex), in the State of Acre. The specimens (n = 30) were caught in mist nets arranged in different ecosystems of the Reserve. After identification, the bird specimens were placed in cloth bags for a maximum of 30 minutes to collect feces. Among the 22 samples collected, 63.63% (n = 14) were positive for endoparasites. The coccidia were the parasites most frequently. Helminths belonging to Ascaridiidae (Nematoda), Strongylida (Nematoda) and Davaneidae (Cestoda) were recorded for the first time in R. carbo in the State of Acre. Parasites belonging to Strongylida and Davaneidae were recorded for the first time in a species of Ramphocelus. These findings add information on the parasitic fauna of wild birds, since in the Amazon region there are few studies on this subject.

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First report of Davaneidae and Strongylida parasitizing Ramphocelus carbo (Aves: Passeriformes: Thraupidae) in the southwest of the Brazilian Amazon region

Investigation of power output from PV arrays under different fault conditions is an essential task to enhance performance of a photovoltaic system under all operating conditions. Significant reduction in power output can occur during various PV faults such as module disconnection, bypass diode failure, bridge fault, and short circuit fault under non-uniform shading conditions. These PV faults may cause several peaks in the characteristics curve of PV arrays, which can lead to failure of the MPPT control strategy. In fact, impact of a fault can differ depending on the type of PV array, and it can make the control of the system more complex. Therefore, consideration of suitable PV arrays with an effective control design is necessary for maximum power output from a PV system. For this purpose, the proposed study presents a comparative study of two intelligent control schemes, i.e., fuzzy logic (FL) and particle swarm optimization (PSO), with a conventional control scheme known as perturb and observe (P&O) for power extraction from a PV system. The comparative analysis is based on the performance of the control strategies under several faults and the types of PV modules, i.e., monocrystalline and thin-film PV arrays. In this study, numerical analysis for complex fault scenarios like multiple faults under partial shading have also been performed. Different from the previous literature, this study will reveal the performance of FL-, PSO-, and P&O-based MPPT strategies to track maximum peak power during multiple severe fault conditions while considering the accuracy and fast-tracking efficiencies of the control techniques. A thorough analysis along with in-depth quantitative data are presented, confirming the superiority of intelligent control techniques under multiple faults and different PV types.

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Saba Gul

Papers

The unprecedented magnitude of the 2017 dengue outbreak in Sri Lanka provides lessons for future mosquito-borne infection control and prevention

Whole blood transfusion improves vascular integrity and increases survival in artemether-treated experimental cerebral malaria.

First report of Davaneidae and Strongylida parasitizing Ramphocelus carbo (Aves: Passeriformes: Thraupidae) in the southwest of the Brazilian Amazon region

Intelligent Control Schemes for Maximum Power Extraction from Photovoltaic Arrays under Faults