Dengue: a new challenge for neurology

Zika and Dengue Virus Autoimmunity: An Overview of Related Disorders and Their Potential Mechanisms

Zika virus (ZIKV) and dengue virus (DENV) are two major mosquito-borne flaviviruses that pose a significant threat to the global public health system, particularly in tropical regions. The clinical outcomes related to these viral pathogens can vary from self-limiting asymptomatic infections to various forms of life-threatening pathological conditions such as haemorrhagic disorders. In addition to the direct effects of the viral pathogens, immune processes play also a significant function in the development of diseases mediated by ZIKV and DENV. Studing these processes is important for developing safer vaccines and targeted therapeutic strategies. These viruses have been reported to trigger various autoimmune disorders affecting different parts of human organ systems. It also has been shown that preexisting immunity to ZIKV or DENV can impact the outcome of subsequent infections caused by another virus. ZIKV and DENV infection can promote the development of autoimmune disorders by different mechanisms, such as molecular mimicry and autoantibody formation. The present review provides an overview of various autoimmune disorders associated with ZIKV and DENV infection and their potential underlying mechanisms.

Rare occurrence of sagittal sinus thrombosis and haemorrhagic infarction with dengue fever: jumping from traditional symptoms to lethal neurological consequences

Introduction and importance

Dengue virus (DENV) is an RNA virus transmitted by Aides mosquito causing dengue fever. There is growing recognition of neurological symptoms associated with DENV infection, some of which might be lethal if left untreated. Case reports describing sagittal sinus thrombosis, as a serious neurologic consequence of dengue infection, are rare. It is still unknown how often sagittal sinus thrombosis occurs and what variables increase the risk in dengue patients.

Case presentation

Herein the authors presented an elderly Sudanese patient diagnosed with dengue fever. He was admitted, then 2 days after admission, the condition was complicated by atrial fibrillation, sagittal sinus thrombosis complicated by massive left temporal lobe infarction with haemorrhagic transformation and recurrent episodes of status epilepticus. After receiving the necessary care, his condition remained the same and no progress or deterioration was seen.

Clinical discussion

Sagittal sinus thrombosis can happen due to several underlying causes. DENV can very rarely lead to such condition. The authors' patient developed this condition, which was later complicated by ischaemic stroke with haemorrhagic transformation and status epilepticus. In addition to a familial history of DVT and a history of myocardial infarction, our patient also acquired cardiac mural thrombus and DVT throughout his illness, which increased the suspicion of a protein C, protein S, or antithrombin 3 deficiency.

Conclusion

Sagittal sinus thrombosis with haemorrhagic infarction associated with thrombocytopenia is a very rare kind of stroke that occurs in dengue. Dengue as a pathogenic mechanism of ischaemic stroke requires validation with further data.

Review of dengue, zika and chikungunya infections in nervous system in endemic areas

Dengue, zika, and chikungunya are arboviruses of great epidemiological relevance worldwide. The emergence and re-emergence of viral infections transmitted by mosquitoes constitute a serious human public health problem. The neurological manifestations caused by these viruses have a high potential for death or sequelae. The complications that occur in the nervous system associated with arboviruses can be a challenge for diagnosis and treatment. In endemic areas, suspected cases should include acute encephalitis, myelitis, encephalomyelitis, polyradiculoneuritis, and/or other syndromes of the central or peripheral nervous system, in the absence of a known explanation. The confirmation diagnosis is based on viral (isolation or RT-PCR) or antigens detection in tissues, blood, cerebrospinal fluid, or other body fluids, increase in IgG antibody titers between paired serum samples, specific IgM antibody in cerebrospinal fluid and serological conversion to IgM between paired serum samples (non-reactive in the acute phase and reactive in the convalescent). The cerebrospinal fluid examination can demonstrate: 1. etiological agent; 2. inflammatory reaction or protein-cytological dissociation depending on the neurological condition; 3. specific IgM, 4. intrathecal synthesis of specific IgG (dengue and chikungunya); 5. exclusion of other infectious agents. The treatment of neurological complications aims to improve the symptoms, while the vaccine represents the great hope for the control and prevention of neuroinvasive arboviruses. This narrative review summarizes the updated epidemiology, general features, neuropathogenesis, and neurological manifestations associated with dengue, zika, and chikungunya infection.

Re-examination of the risk of dementia after dengue virus infection: A population-based cohort study

Dengue infection can affect the central nervous system and cause various neurological complications. Previous studies also suggest dengue was associated with a significantly increased long-term risk of dementia. A population-based cohort study was conducted using national health databases in Taiwan and included 37,928 laboratory-confirmed dengue patients aged ≥ 45 years between 2002 and 2015, along with 151,712 matched nondengue individuals. Subdistribution hazard regression models showed a slightly increased risk of Alzheimer's disease, and unspecified dementia, non-vascular dementia, and overall dementia in dengue patients than the nondengue group, adjusted for age, sex, area of residence, urbanization level, income, comorbidities, and all-cause clinical visits within one year before the index date. After considering multiple comparisons using Bonferroni correction, only overall dementia and non-vascular dementia remained statistically significant (adjusted SHR 1.13, 95% CI 1.05-1.21, p = 0.0009; E-value 1.51, 95% CI 1.28-NA). Sensitivity analyses in which dementia cases occurring in the first three or five years after the index dates were excluded revealed no association between dengue and dementia. In conclusion, this study found dengue patients had a slightly increased risk of non-vascular dementia and total dementia than those without dengue. However, the small corresponding E-values and sensitivity analyses suggest the association between dengue and dementia may not be causal.

A Rare Combination: Dengue Fever Complicated With Guillain-Barre Syndrome

Guillain-Barre syndrome (GBS) is an uncommon neurological complication of dengue viral infection. It is more commonly reported with Campylobacter jejuni, Epstein-Barr virus, and Cytomegalovirus infection. We report an uncommon case of a 49-year-old man with dengue fever, who developed bilateral lower limb weakness and areflexia on day two of dengue illness. He was diagnosed with GBS as a sequel of dengue infection with the nerve conduction study showing evidence of demyelinating neuropathy. He recovered gradually without immunotherapy and was discharged after a week of hospitalization.

Secondary dengue serotype 1 infection causing dengue shock syndrome with rhombencephalitis and bleeding associated with refractory thrombocytopenia: A case report

Background

Dengue has a wide spectrum of manifestations, from an asymptomatic condition to dengue shock syndrome. Extensive plasma leakage, severe bleeding, or both, could lead to dengue shock syndrome, a common cause of death in dengue-infected patients. Thrombocytopenia is a common laboratory finding in dengue, which correlates with the disease severity and rapidly resolves during the recovery phase. Therefore, refractory thrombocytopenia is rare in patients with dengue. Rhombencephalitis is an inflammatory disease affecting the hindbrain, rarely associated with dengue. We report the second case of dengue-associated rhombencephalitis, wherein the patient developed dengue shock syndrome and severe bleeding associated with refractory thrombocytopenia.

Case report

A 47-year-old Thai female with secondary dengue serotype 1 infection developed dengue shock syndrome with rhombencephalitis, manifested as altered sensorium and status epilepticus in the critical phase. Cerebrospinal fluid analysis showed pleocytosis with predominantly mononuclear cells and high protein levels. Magnetic resonance imaging of the brain showed multifocal brain signal abnormalities involving the medulla oblongata, pons, midbrain, bilateral hippocampi, thalami, posterior limb of internal capsules, external capsules, and deep hemispheric white matter. The patient had partial neurological recovery following rhombencephalitis for one month. During the recovery phase, severe bleeding with refractory thrombocytopenia and acute kidney injury were observed. Methylprednisolone with eltrombopag was administered, which resulted in an increased the platelet count, cessation of bleeding and recovery of kidney function within 4 days.

Conclusions

Dengue is a potential cause of rhombencephalitis. Dengue-associated rhombencephalitis develops during the critical phase, with only partial neurological recovery. However, severe bleeding and refractory thrombocytopenia were also observed during the recovery phase. Methylprednisolone with a thrombopoietin receptor agonist could be an effective treatment for increasing platelet count and stopping bleeding in dengue.

Differential Infectivity of Human Neural Cell Lines by a Dengue Virus Serotype-3 Genotype-III with a Distinct Nonstructural Protein 2A (NS2A) Amino Acid Substitution Isolated from the Cerebrospinal Fluid of a Dengue Encephalitis Patient

Dengue encephalitis is considered as a severe but unusual clinical presentation of dengue infection. Limited molecular information is available on the neurotropism of dengue virus (DENV), highlighting the need for further research. During a dengue outbreak in Vietnam in 2013, two DENV-3 strains were isolated, in which one was isolated from cerebrospinal fluid (CSF) samples from a dengue encephalitis patient and another strain was isolated from a patient with classical dengue fever in Hai Phong, Vietnam. DENV serotype-3 (DENV-3) isolated from these samples belonged to genotype III, marking the first report of this genotype in the country at that time. Genetic variation between both strains was elucidated by using a full genome sequencing by next-generation sequencing (NGS). The infectivity of the isolated DENV-3 strains was further characterized using human and mouse neuronal cell lines. Phylogenetic analysis of the isolates demonstrated high homogeneity between the CSF-derived and serum-derived DENV-3, in which the full genome sequences of the CSF-derived DENV-3 presented a Thr-1339-Ile mutation in the nonstructural 2A (NS2A) protein. The CSF-derived DENV-3 isolate grew preferentially in human neuronal cells, with a significant proportion of cells that were positive for nonstructural 1 (NS1), nonstructural 4B (NS4B), and nonstructural 5 (NS5) antigens. These results suggest that NS2A may be a crucial region in the neuropathogenesis of DENV-3 and its growth in human neuronal cells. Taken together, our results demonstrate that a CSF-derived DENV-3 has unique infectivity characteristics for human neuronal cells, which might play a crucial role in the neuropathogenesis of DENV infection.

Neurological Complications of Dengue Fever

PURPOSE OF REVIEW

To discuss the neurological complications of dengue virus (DENV) infection and their pathogenesis.

RECENT FINDINGS

Include recognition of the four different serotypes of DENV and their epidemiology as well as recognition of the expanded dengue syndrome encompassing multisystem involvement in the severe form of the disease including involvement of the central nervous system (CNS). DENV is a neurotropic virus with the ability to infect the supporting cells of the CNS. Neural injury during the acute stage of the infection results from direct neuro-invasion and/or the phenomenon of antibody-dependent enhancement, resulting in plasma leakage and coagulopathy. Immune mechanisms have been implicated in the development of the delayed neurological sequelae through molecular mimicry. A myriad of neurological syndromes has been described as a result of the involvement of the CNS, the peripheral nervous system (PNS), or both. Neurological manifestations in DENV infection are increasingly being recognized, some of which are potentially fatal if not treated promptly. DENV encephalopathy and encephalitis should be considered in the differential diagnosis of other acute febrile encephalopathies, autoimmune encephalitides, and in cases of encephalopathy/encephalitis related to SARS-CoV2 infection, especially in dengue-endemic areas. Acute disseminated encephalomyelitis (ADEM) may be occasionally encountered. Clinicians should be knowledgeable of the expanded dengue syndrome characterized by the concurrent compromise of cardiac, neurological, gastrointestinal, renal, and hematopopoietic systems. Isolated cranial nerve palsies occur rather uncommonly and are often steroid responsive. These neuropathies may result from the direct involvement of cranial nerve nuclei or nerve involvement or may be immune-mediated. Even if the diagnosis of dengue is confirmed, it is absolutely imperative to exclude other well-known causes of isolated cranial nerve palsies. Ischemic and hemorrhagic strokes may occur following dengue fever. The pathogenesis may be beyond the commonly observed thrombocytopenia and include cerebral vasculitis. Involvement of ocular blood vessels may cause maculopathy or retinal hemorrhages. Posterior reversible encephalopathy syndrome (PRES) is uncommon and possibly related to dysregulated cytokine release phenomena. Lastly, any patient developing acute neuromuscular weakness during the course or within a fortnight of remission from dengue fever must be screened for acute inflammatory demyelinating polyneuropathy (AIDP), hypokalemic paralysis, or acute myositis. Rarely, a Miller-Fisher-like syndrome with negative anti-GQ1b antibody may develop.

Risk Factors for Mortality in Patients with Dengue: A Systematic Review and Meta-Analysis

OBJECTIVE

To investigate risk factors for mortality in dengue.

METHODS

Systematic review and meta-analysis searching MEDLINE, Embase, SciELO, LILACS Bireme, and OpenGrey to identify eligible observational studies of patients with dengue, of both genders, aged 14 years or older, that analyzed risk factors associated with mortality and reported adjusted risk measures with their respective confidence intervals (CIs). We estimated the pooled weighted mean difference and 95% CIs with a DerSimonian and Laird random-effects model. Methodological quality was assessed using the Newcastle-Ottawa Scale.

RESULTS

Of 1,170 citations reviewed, 18 papers, with a total of 25,851 patients, were included in the systematic review and 12 in the meta-analysis. Severe hepatitis (OR 29.222, 95% CI: 3.876-220.314), dengue shock syndrome (OR 23.575, 95% CI 3.664-151.702), altered mental status (OR 3.76, 95% CI 1.67-8.42), diabetes mellitus (OR 3.698, 95% CI 1.196-11.433), and higher pulse rate (OR 1.039, 95% CI 1.011-1.067) are associated with mortality in patients with dengue. All studies included were classified as having a high quality.

CONCLUSIONS

Proper identification and management of these risk factors should be considered to improve patient outcomes and reduce the hidden burden of this neglected tropical disease. Future well-designed studies are needed to investigate the association of other clinical, radiological, and laboratorial findings with mortality in dengue, as well as to develop prognostic models based on the risk factors found in our study.

[Dengue virus circulation in West Africa: An emerging public health issue]

Dengue is the most widespread arbovirosis in the world, with approximately 390 million cases per year, 96 millions of which have clinical manifestations and 25,000 deaths. In West Africa, the circulation of this virus in human populations was first reported in the 1960s in Nigeria. Clinical diagnosis of dengue in West Africa is made difficult by the existence of other diseases with similar clinical presentations. Biological diagnosis remains therefore the only alternative. This biological diagnosis requires high quality equipment and well-trained personnel, which are not always available in resource-limited countries. Thus, many cases of dengue fever are consistently reported as malaria, leading to mismanagement, which can have serious consequences on the health status of patients. It is therefore necessary to set up surveillance systems for febrile infections of unknown origin in Africa by strengthening the diagnostic capacities of national laboratories.

An unusual case of acute motor axonal neuropathy (AMAN) complicating dengue fever

Neurological complications are increasingly being reported in dengue fever, and the dengue virus is now recognized as a neurotrophic virus. The damage caused by inflammatory cytokines in the febrile phase and molecular mimicry in the recovery phase is responsible for these neurological manifestations. We report such an unusual neurological complication occurring in a 27-year-old female in the recovery phase of dengue fever, who developed an acute onset of ascending symmetric weakness of all four limbs without any sensory, autonomic, cerebellar, or cranial nerve involvement. She was diagnosed as having an acute motor axonal neuropathy (AMAN) variant of Guillain-Barre syndrome (GBS) based on a nerve conduction study (NCS) showing axonal neuropathy and contrast-enhanced magnetic resonance imaging (CE-MRI) showing root enhancement at the region of the cauda equina. She was treated with intravenous immunoglobulin (IVIG) and showed full recovery from symptoms with treatment. Our case highlights the importance of being aware of such rare neurological complications in dengue fever. Early detection and rapid initiation of treatment can lead to the complete reversal of neurological deficits.

Dengue and dementia risk: A nationwide longitudinal study

BACKGROUND

Accumulating evidence suggests neurological manifestations after dengue infection. However, the relationship between dengue and long-term neurocognitive sequel remains unclear.

METHODS

We recruited 816 patients with dengue and 8,160 controls between 1997 and 2012 using data from Taiwan National Health Insurance Research Database and followed them up until the end of 2013. Individuals who exhibited any type of dementia were identified during the follow-up period. Cox regression analyses were performed with adjustments for demographic data and medical and mental comorbidities (cerebrovascular diseases, traumatic brain injury, hypertension, dyslipidemia, diabetes mellitus, depression, alcohol use disorder, and substance use disorder). The E-value for the causality of the evidence was calculated. Sensitivity analysis was conducted to exclude patients with prodromal dementia.

RESULTS

Patients with dengue were more likely to develop dementia (hazard ratio [HR]: 2.23, 95% confidence interval [CI]: 1.51-3.28), Alzheimer's disease (HR: 3.03, 95% CI: 1.08-8.45), and unspecified dementia (HR: 2.25, 95% CI: 1.43-3.53), but not vascular dementia compared to controls during the follow-up period. Sensitivity analyses after exclusion of the observation period over the first three years or first five years and after exclusion of patients' enrollment before 2010 or 2008 showed consistent findings. The E-values for the HR (range 3.62-5.51) supported the association between dengue and subsequent dementia among the whole population, men, and women.

CONCLUSION

The risk of dementia was 2.23-fold higher in patients diagnosed with dengue during the follow-up period than in the controls. Further studies are necessary to investigate the underlying pathophysiology of dengue and dementia.

Dengue Infection: Not Just Fever—A Rare Presentation with Literature Review

Dengue fever is a common viral infection in the tropical areas, especially in India. However, dengue infection presenting as hemorrhagic encephalitis is rare. A 10-year-old girl presented with fever, headache, vomiting, and seizures followed by altered sensorium. Her blood serum was positive for antidengue immunoglobulin M enzyme-linked immunosorbent assay (ELISA) and NS1Ag, and cerebrospinal fluid study showed lymphocytic pleocytosis. Magnetic resonance imaging T2-weighted and fluid-attenuated inversion recovery (FLAIR) images showed hyperintensities involving the bilateral thalami, pons, and midbrain with patchy hemorrhage. Despite all supportive measures, she expired 3 days after admission. Our case highlights that dengue encephalitis may present even in the absence of other classical signs.

Unusual Manifestations of Dengue Fever: A Review on Expanded Dengue Syndrome

Dengue infection may manifest as dengue fever (DF), dengue hemorrhagic fever (DHF), and dengue shock syndrome (DSS). The World Health Organization (WHO) came up with the term "expanded dengue syndrome" (EDS) to designate cases which do not fall into either DHF or DSS, with unusual manifestations in other organs such as the cardiovascular system, the nervous system, the kidneys, the gut, and the hematological system, which have been increasingly reported and called EDS. Furthermore, EDS is becoming widespread globally with unusual features and increased severity. There are increasing reports of under-recognized and infrequent manifestations with severe organ involvement. This review gives knowledge of expanded dengue syndrome which helps to catch the diagnosis of dengue early, particularly during the ongoing epidemics and escaping from further series of unnecessary investigations.

Case report: Mononeuritis multiplex in the course of dengue fever

Background

Dengue fever usually presents as a self-limiting acute febrile illness with worsening thrombocytopenia, with a small minority of patients developing hemorrhagic or life-threatening complications. Organ specific manifestations like myocarditis, acalculous cholecystitis, encephalitis has been described but are uncommon presentations. Even more rarely, such manifestations are the presenting complaint of Dengue fever. In this case report, we highlight a case of Dengue fever where unrelated neuropathies were the presenting complaint.

Case presentation

An elderly man presents with 1 day of diplopia and left foot drop, associated with 2 days history of fever. A decreasing white cell count (WBC) and platelet on the 2nd day of admission prompted Dengue virus to be tested and a positive NS-1 antigen was detected, confirming the diagnosis of Dengue fever. He was treated with supportive treatment with a short duration of intravenous fluids recovered uneventfully and was discharged 6 days after admission with almost full resolution of diplopia and partial resolution of left foot drop. Left foot drop recovered completely 2 weeks later.

Conclusion

Neurological manifestations can be the presenting symptoms in Dengue fever, a diagnosis which should be borne in mind when such symptoms present in patients from endemic areas or in returning travellers from these areas.

Dengue Virus Degrades USP33-ATF3 Axis via Extracellular Vesicles to Activate Human Microglial Cells

Dengue virus (DENV) infection disrupts host innate immune signaling at various checkpoints. Cellular levels and stability of intermediate signaling molecules are a crucial hijacking point for a successful viral pathogenesis. Stability and turnover of all the cellular proteins including intermediate signaling molecules are principally regulated by proteasomal degradation pathway. In this study, we show that how DENV infection and particularly DENV-NS1 can modulate the host extracellular vesicle (EV) cargo to manipulate the deubiquitination machinery of the human microglial cell (CHME3). We have performed EV harvesting, size analysis by nanoparticle tracking analysis, identification of cargo microRNA via quantitative PCR, microRNA target validation by overexpression, and knockdown via mimics and anti-miRs, immunoblotting, dual luciferase reporter assay, in vivo ubiquitination assay, chase assay, and promoter activity assay to reach the conclusion. In this study, we show that DENV-infected monocytes and DENV-NS1-transfected cells release high amounts of EVs loaded with miR-148a. These EVs get internalized by human microglial cells, and miR-148a suppresses the ubiquitin-specific peptidase 33 (USP33) protein expression levels via binding to its 3' untranslated region. Reduced USP33 in turn decreases the stability of cellular ATF3 protein via deubiquitylation. ATF3 acts as a suppressor of major proinflammatory gene expression pathways of TNF-α, NF-κB, and IFN-β. Our mechanistic model explains how DENV uses the EV pathway to transfer miR-148a for modulating USP33 and downstream ATF3 levels in human microglial cells and contributes in neuroinflammation within the CNS.

Dengue Encephalitis in Children "Not an Uncommon Entity but Is Rarely Thought of": A Case Report

Dengue fever is a common viral infection in the tropical areas, especially in India. The clinical manifestations of dengue infection are broad-spectrum, ranging from asymptomatic to life-threatening dengue shock syndrome. Usually, the dengue virus does not cause neurologic manifestations, but recently this has been documented in some cases. However, there is increasing evidence for dengue viral neurotropism, suggesting there may be an element of direct encephalitis in some dengue patients. Here we are reporting a case of dengue encephalitis in a 2-year-old female child from rural India who was presented with a history of fever, altered sensorium, and seizures. Blood test results of dengue immunoglobulin M (IgM) antibodies were positive. Cerebrospinal fluid analysis showed lymphocytic pleocytosis with elevated proteins and normal glucose. Neuroimaging was normal. In addition, other causes of encephalitis were ruled out by appropriate laboratory investigations. Our case highlights that dengue encephalitis may present even in the absence of neuroimaging findings with classical clinical signs. Hence, dengue encephalitis should be considered in the differential diagnosis of fever with altered sensorium and seizures, especially in areas where dengue fever is endemic.

Dengue infection in mice inoculated by the intracerebral route: neuropathological effects and identification of target cells for virus replication

Dengue is an important arboviral infection, causing a broad range symptom that varies from life-threatening mild illness to severe clinical manifestations. Recent studies reported the impairment of the central nervous system (CNS) after dengue infection, a characteristic previously considered as atypical and underreported. However, little is known about the neuropathology associated to dengue. Since animal models are important tools for helping to understand the dengue pathogenesis, including neurological damages, the aim of this work was to investigate the effects of intracerebral inoculation of a neuroadapted dengue serotype 2 virus (DENV2) in immunocompetent BALB/c mice, mimicking some aspects of the viral encephalitis. Mice presented neurological morbidity after the 7^th day post infection. At the same time, histopathological analysis revealed that DENV2 led to damages in the CNS, such as hemorrhage, reactive gliosis, hyperplastic and hypertrophied microglia, astrocyte proliferation, Purkinje neurons retraction and cellular infiltration around vessels in the pia mater and in neuropil. Viral tropism and replication were detected in resident cells of the brain and cerebellum, such as neurons, astrocyte, microglia and oligodendrocytes. Results suggest that this classical mice model might be useful for analyzing the neurotropic effect of DENV with similarities to what occurs in human.

Management of Central Nervous System Infections, Vientiane, Laos, 2003-2011

During 2003–2011, we recruited 1,065 patients of all ages admitted to Mahosot Hospital (Vientiane, Laos) with suspected central nervous system (CNS) infection. Etiologies were laboratory confirmed for 42.3% of patients, who mostly had infections with emerging pathogens: viruses in 16.2% (mainly Japanese encephalitis virus [8.8%]); bacteria in 16.4% (including Orientia tsutsugamushi [2.9%], Leptospira spp. [2.3%], and Rickettsia spp. [2.3%]); and Cryptococcus spp. fungi in 6.6%. We observed no significant differences in distribution of clinical encephalitis and meningitis by bacterial or viral etiology. However, patients with bacterial CNS infection were more likely to have a history of diabetes than others. Death (26.3%) was associated with low Glasgow Coma Scale score, and the mortality rate was higher for patients with bacterial than viral infections. No clinical or laboratory variables could guide antibiotic selection. We conclude that high-dependency units and first-line treatment with ceftriaxone and doxycycline for suspected CNS infections could improve patient survival in Laos.

Rapidly progressive dementia with seizures: a post-dengue complication

Dengue infection can cause various effects on the central and peripheral nervous systems. Direct neurotropism and immunological mechanisms are responsible for most such neurological manifestations. We present the case of a 64-year-old woman with rapidly progressive dementia with seizures following dengue infection.

Dengue Virus Infection of Blood-Brain Barrier Cells: Consequences of Severe Disease

More than 500 million people worldwide are infected each year by any of the four-dengue virus (DENV) serotypes. The clinical spectrum caused during these infections is wide and some patients may develop neurological alterations during or after the infection, which could be explained by the cryptic neurotropic and neurovirulent features of flaviviruses like DENV. Using in vivo and in vitro models, researchers have demonstrated that DENV can affect the cells from the blood-brain barrier (BBB) in several ways, which could result in brain tissue damage, neuronal loss, glial activation, tissue inflammation and hemorrhages. The latter suggests that BBB may be compromised during infection; however, it is not clear whether the damage is due to the infection per se or to the local and/or systemic inflammatory response established or activated by the BBB cells. Similarly, the kinetics and cascade of events that trigger tissue damage, and the cells that initiate it, are unknown. This review presents evidence of the BBB cell infection with DENV and the response established toward it by these cells; it also describes the consequences of this response on the nervous tissue, compares these evidence with the one reported with neurotropic viruses of the Flaviviridae family, and shows the complexity and unpredictability of dengue and the neurological alterations induced by it. Clinical evidence and in vitro and in vivo models suggest that this virus uses the bloodstream to enter nerve tissue where it infects the different cells of the neurovascular unit. Each of the cell populations respond individually and collectively and control infection and inflammation, in other cases this response exacerbates the damage leaving irreversible sequelae or causing death. This information will allow us to understand more about the complex disease known as dengue, and its impact on a specialized and delicate tissue like is the nervous tissue.

Neurological Manifestations of Dengue Infection

Dengue counts among the most commonly encountered arboviral diseases, representing the fastest spreading tropical illness in the world. It is prevalent in 128 countries, and each year >2.5 billion people are at risk of dengue virus infection worldwide. Neurological signs of dengue infection are increasingly reported. In this review, the main neurological complications of dengue virus infection, such as central nervous system (CNS), peripheral nervous system, and ophthalmic complications were discussed according to clinical features, treatment and possible pathogenesis. In addition, neurological complications in children were assessed due to their atypical clinical features. Finally, dengue infection and Japanese encephalitis were compared for pathogenesis and main clinical manifestations.

Rapidly Resolving Weakness Related to Hypokalemia in Patients Infected With Dengue Virus

OBJECTIVES

Dengue is a mosquito-borne disease caused by arbovirus and well known for its typical fever with thrombocytopenia syndrome. Acute hypokalemic quadriparesis is a rare presentation of dengue with uncertain pathogenesis. We aim to describe the clinical and biochemical characteristics of rapidly resolving weakness related to hypokalemia in patients infected with dengue virus.

METHODS

A retrospective review of the records of patients with diagnosis of dengue-associated hypokalemic weakness was performed. Demography, clinical, biochemical characteristics, and outcome of the patients were recorded during acute phase of illness.

RESULTS

Our study cohort comprised 12 patients and all were males from urban dwelling. The median age was 34.5 years (range, 18-50). Presentation was acute onset rapidly worsening pure motor quadriparesis preceded by short lasting febrile episode. Weakness ranged from 2/5 to 4/5 on Medical Research Council (MRC) scale with generalized hyporeflexia or areflexia. The baseline serum potassium was mean ± SD (2.7 ± 0.48 mmol/L). All patients showed elevation of liver transaminases and elevated creatine phosphokinase level. Weakness improved in 24-72 hours in all patients with correction of serum potassium.

CONCLUSIONS

Dengue-associated acute hypokalemic paralysis is an underrecognized entity having favorable outcome. It should be suspected in patients presenting as acute pure motor quadriparesis after febrile illness in dengue endemic areas.

Acute disseminated encephalomyelitis complicating dengue infection with neuroimaging mimicking multiple sclerosis: A report of two cases

Acute disseminated encephalomyelitis (ADEM) complicating dengue infection is still exceedingly rare even in endemic countries such as Malaysia. Here we report two such cases, the first in an elderly female patient and the second in a young man. Both presented with encephalopathy, brainstem involvement and worsening upper and lower limb weakness. Initial magnetic resonance imaging (MRI) of the brain was normal in the first case. Serum for dengue Ig M and NS-1 was positive in both cases. Cerebrospinal fluid (CSF) showed pleocytosis in both with Dengue IgM and NS-1 positive in the second case but not done in the first. MRI brain showed changes of perpendicular subcortical palisading white matter, callosal and brainstem disease mimicking multiple sclerosis (MS) in both patients though in the former case there was a lag between the onset of clinical symptoms and MRI changes which was only clarified on reimaging. The temporal evolution and duration of the clinical symptoms, CSF changes and neuroimaging were more suggestive of Dengue ADEM rather than an encephalitis though initially the first case began as dengue encephalitis. Furthermore in dengue encephalitis neuroimaging is usually normal or rarely edema, haemorrhage, brainstem, thalamic or focal lesions are seen. Therefore, early recognition of ADEM as a sequelae of dengue infection with neuroimaging mimicking MS and repeat imaging helped in identifying these two cases. Treatment with intravenous steroids followed by maintenance oral steroids produced good outcome in both patients.

A Two-Year Review on Epidemiology and Clinical Characteristics of Dengue Deaths in Malaysia, 2013-2014

Background

Dengue infection is the fastest spreading mosquito-borne viral disease, which affects people living in the tropical and subtropical countries. Malaysia had large dengue outbreaks in recent years. We aimed to study the demographics and clinical characteristics associated with dengue deaths in Malaysia.

Methods

We conducted a retrospective review on all dengue deaths that occurred nationwide between 1^st January 2013 and 31^st December 2014. Relevant data were extracted from mortality review reports and investigational forms. These cases were categorized into children (<15 years), adults (15–59 years) and elderly (≥60 years) to compare their clinical characteristics.

Results

A total of 322 dengue deaths were reviewed. Their mean age was 40.7±19.30 years, half were females and 72.5% were adults. The median durations of first medical contact, and hospitalization were 1 and 3 days, respectively. Diabetes and hypertension were common co-morbidities among adults and elderly. The most common warning signs reported were lethargy and vomiting, with lethargy (p = 0.038) being more common in children, while abdominal pain was observed more often in the adults (p = 0.040). But 22.4% did not have any warning signs. Only 34% were suspected of dengue illness at their initial presentation. More adults developed severe plasma leakage (p = 0.018). More than half (54%) suffered from multi-organ involvement, and 20.2% were free from any organ involvement. Dengue deaths occurred at the median of 3 days post-admission. Dengue shock syndrome (DSS) contributed to more than 70% of dengue deaths, followed by severe organ involvement (69%) and severe bleeding (29.7%).

Conclusion

In Malaysia, dengue deaths occurred primarily in adult patients. DSS was the leading cause of death, regardless of age groups. The atypical presentation and dynamic progression of severe dengue in this cohort prompts early recognition and aggressive intervention to prevent deaths.

Trial Registration

National Medical Research Registry (NMRR, NMRR-14-1374-23352)

Dengue infection, especially severe dengue, affected more of adults from working age groups in the society. They can present with non-specific symptoms mimicking many other febrile illnesses, or severe symptoms suggestive of sepsis, with low suspicion of dengue. The clinical progression in severe dengue can be dynamic and sometimes unanticipated, whereby patients can deteriorate rapidly in a short period of time and succumb to death. Although children tend to have central nervous system involvement, where they presented with confusion and/ or seizure, and more elderly had heart involvement, the primary cause of dengue death, dengue shock syndrome, did not differ across different age groups.

Zika Virus: the Latest Newcomer

Since the beginning of this century, humanity has been facing a new emerging, or re-emerging, virus threat almost every year: West Nile, Influenza A, avian flu, dengue, Chikungunya, SARS, MERS, Ebola, and now Zika, the latest newcomer. Zika virus (ZIKV), a flavivirus transmitted by Aedes mosquitoes, was identified in 1947 in a sentinel monkey in Uganda, and later on in humans in Nigeria. The virus was mainly confined to the African continent until it was detected in south-east Asia the 1980's, then in the Micronesia in 2007 and, more recently in the Americas in 2014, where it has displayed an explosive spread, as advised by the World Health Organization, which resulted in the infection of hundreds of thousands of people. ZIKV infection was characterized by causing a mild disease presented with fever, headache, rash, arthralgia, and conjunctivitis, with exceptional reports of an association with Guillain-Barre syndrome (GBS) and microcephaly. However, since the end of 2015, an increase in the number of GBS associated cases and an astonishing number of microcephaly in fetus and new-borns in Brazil have been related to ZIKV infection, raising serious worldwide public health concerns. Clarifying such worrisome relationships is, thus, a current unavoidable goal. Here, we extensively review what is currently known about ZIKV, from molecular biology, transmission routes, ecology, and epidemiology, to clinical manifestations, pathogenesis, diagnosis, prophylaxis, and public health.

Advances and new insights in the neuropathogenesis of dengue infection

Dengue virus (DENV) infects approximately 390 million persons every year in more than 100 countries. Reports of neurological complications are more frequently. The objective of this narrative review is to bring up the advances in the dengue neuropathogenesis. DENV can access the nervous system through blood-brain barrier disturbance mediated by cytokine. The blood-cerebrospinal fluid (CSF) barrier seems to be also involved, considering the presence of the virus in the CSF of patients with neurological manifestations. As for neurotropism, several studies showed the presence of RNA and viral antigens in brain tissue and CSF in humans. In murine model, different virus mutations were associated to neurovirulence. Despite the advances in the dengue neuropathogenesis, it is still necessary to determine a more appropriate animal model and increase the number of cases of autopsy. The detection of neurovirulence markers may contribute to establish a prognosis, the disease control and vaccine development.

Differential replicative ability of clinical dengue virus isolates in an immunocompetent C57BL/6 mouse model

BACKGROUND

Several experimental animal models have been used to study the pathogenesis of dengue disease; however, most of the studies used laboratory-adapted viruses, which lack the virulence of viruses circulating in humans. The aim of this study was to analyze the ability of clinical Dengue virus (DENV) isolates (D2/BR/RP/RMB/09 and D3/BR/SL3/02) to infect immunocompetent C57BL/6 mice.

METHODS

Two strategies of intraperitoneal infection, which were based on the concept of the antibody dependent enhancement phenomenon, were used. In one strategy, the animals were inoculated with macrophages infected in vitro with dengue viruses, which were incubated with enhancing antibodies, and in the other strategy, the animals were inoculated with a complex of enhancing antibodies and dengue viruses.

RESULTS

The D3/BR/SL3/08 isolate showed a higher ability of infection (virus RNA was more frequently detected in the serum and in several organs) in the experimental model compared to both the D2/BR/RP/RMB/2009 isolate and a laboratory adapted DENV-1 strain (Mochizuki strain), regardless of the infection strategy used. The main features of the D3/BR/SL3/08 isolate were its neuroinvasiveness and the induction of an extended period of viremia. Enhancing antibodies did not influence on the infection of animals when macrophages were used, but the level of viremia was increased when they were used as a complex with a D3/BR/SL3/02 isolate.

DISCUSSION

We showed that DENV isolates could infect immunocompetent C57BL/6 mice, which have has been previously used to study some aspect of dengue disease when infected with laboratory adapted strains. DENV genome was detected in the same organs found in humans when autopsy and biopsy samples were analyzed, showing that C57BL/6 mice reproduce some aspects of the DENV tropism observed in humans. The main difference observed between the D3/BR/SL3/02 and D2/BR/RP/RMB/2009 clinical isolates was the neuroinvasive ability of the first one. Neuroinvasiveness has been described in some DENV infected cases and is common for other members of the Flavivirus genus.

CONCLUSIONS

These results suggest that C57BL/6 mice can be used as an experimental model to evaluate virulence differences among DENV clinical isolates.

Post dengue neurological complication

Dengue infection is highly endemic in many tropical countries including Malaysia. However, neurological complications arising from dengue infection is not common; Gullain-Barre syndrome (GBS) is one of these infrequent complications. In this paper, we have reported a case in which a 39-year-old woman presented with a neurological complication of dengue infection without typical symptoms and signs of dengue fever. She had a history of acute gastroenteritis (AGE) followed by an upper respiratory tract infection (URTI) weeks prior to her presentation rendering GBS secondary to the post viral URTI and AGE as the most likely diagnosis. Presence of thrombocytopenia was the only clue for dengue in this case.

Delivery of antiviral small interfering RNA with gold nanoparticles inhibits dengue virus infection in vitro

Dengue virus (DENV) infection in humans can cause flu-like illness, life-threatening haemorrhagic fever or even death. There is no specific anti-DENV therapeutic or approved vaccine currently available, partially due to the possibility of antibody-dependent enhancement reaction. Small interfering RNAs (siRNAs) that target specific viral genes are considered a promising therapeutic alternative against DENV infection. However, in vivo, siRNAs are vulnerable to degradation by serum nucleases and rapid renal excretion due to their small size and anionic character. To enhance siRNA delivery and stability, we complexed anti-DENV siRNAs with biocompatible gold nanoparticles (AuNPs) and tested them in vitro. We found that cationic AuNP-siRNA complexes could enter Vero cells and significantly reduce DENV serotype 2 (DENV-2) replication and infectious virion release under both pre- and post-infection conditions. In addition, RNase-treated AuNP-siRNA complexes could still inhibit DENV-2 replication, suggesting that AuNPs maintained siRNA stability. Collectively, these results demonstrated that AuNPs were able to efficiently deliver siRNAs and control infection in vitro, indicating a novel anti-DENV strategy.

Dengue encephalitis-A rare manifestation of dengue fever

The clinical spectrum of dengue fever ranges from asymptomatic infection to dengue shock syndrome. Dengue is classically considered a non-neurotropic virus. Neurological complications are not commonly seen in dengue. The neurological manifestations seen in dengue are encephalitis, meningitis, encephalopathy, stroke and Guillain-Barré syndrome. Dengue encephalitis is a rare disease. We report an interesting case of dengue encephalitis from Southern India. A 49-year-old gentleman presented with fever, altered sensorium and seizures. Dengue NS-1 antigen test was reactive. Dengue IgM was also positive. CSF PCR was negative for herpes simplex 1 & 2. Dengue encephalitis should be considered in the differential diagnosis of fever with altered sensorium, especially in countries like India where dengue is rampant.

Neurological complications in dengue infection: a review for clinical practice

Dengue is an important global public health problem. The World Health Organization estimates that 2/5 of entire world population are in risk of dengue infection. Almost 50 millions cases occur annually, with at least 20 thousand deaths. The etiological agent of this acute febrile disease is a single-strand positive-sense RNA virus of Flavivirus genus. It is an arboviral disease transmitted by Aedes sp. mosquitoes (Aedes aegypti and A. albopictus). Most infected individuals present asymptomatic infection, but some may develop clinical signs. Therefore, a wide spectrum of illness can be observed, ranging from unapparent, mild disease, called dengue fever, to a severe and occasionally fatal dengue hemorrhagic fever/dengue shock syndrome. Currently, neurological manifestations related to dengue infections are increasingly been observed and appears as a challenge for medical practice. In this study the neurological complications of dengue infection will be reviewed, focusing a better understanding of the disease for the clinical practice.

Estimating the burden of Japanese encephalitis virus and other encephalitides in countries of the mekong region

Diverse aetiologies of viral and bacterial encephalitis are widely recognized as significant yet neglected public health issues in the Mekong region. A robust analysis of the corresponding health burden is lacking. We retrieved 75 articles on encephalitis in the region published in English or in French from 1965 through 2011. Review of available data demonstrated that they are sparse and often derived from hospital-based studies with significant recruitment bias. Almost half (35 of 75) of articles were on Japanese encephalitis virus (JEV) alone or associated with dengue. In the Western Pacific region the WHO reported 30,000-50,000 annual JEV cases (15,000 deaths) between 1966 and 1996 and 4,633 cases (200 deaths) in 2008, a decline likely related to the introduction of JEV vaccination in China, Vietnam, or Thailand since the 1980s. Data on dengue, scrub typhus and rabies encephalitis, among other aetiologies, are also reviewed and discussed. Countries of the Mekong region are undergoing profound demographic, economic and ecological change. As the epidemiological aspects of Japanese encephalitis (JE) are transformed by vaccination in some countries, highly integrated expert collaborative research and objective data are needed to identify and prioritize the human health, animal health and economic burden due to JE and other pathogens associated with encephalitides.

Dengue virus type 2: protein binding and active replication in human central nervous system cells

An increased number of dengue cases with neurological complications have been reported in recent years. The lack of reliable animal models for dengue has hindered studies on dengue virus (DENV) pathogenesis and cellular tropism in vivo. We further investigate the tropism of DENV for the human central nervous system (CNS), characterizing DENV interactions with cell surface proteins in human CNS cells by virus overlay protein binding assays (VOPBA) and coimmunoprecipitations. In VOPBA, three membrane proteins (60, 70, and 130 kDa) from the gray matter bound the entire virus particle, whereas only a 70 kDa protein bound in white matter. The coimmunoprecipitation assays revealed three proteins from gray matter consistently binding virus particles, one clearly distinguishable protein (~32 kDa) and two less apparent proteins (100 and 130 kDa). Monoclonal anti-NS3 targeted the virus protein in primary cell cultures of human CNS treated with DENV-2, which also stained positive for NeuH, a neuron-specific marker. Thus, our results indicate (1) that DENV-2 exhibited a direct tropism for human neurons and (2) that human neurons sustain an active DENV replication as was demonstrated by the presence of the NS3 viral antigen in primary cultures of these cells treated with DENV-2.

Acute Compressive Ulnar Neuropathy In A Patient Of Dengue Fever: An Unusual Presentation

Introduction:

Dengue haemorrhagic fever is known for its haemorrhagic and neurologic complications. Neurologic complications are caused by three mechanism namely neurotropism, systemic complications causing encephalopathy and postinfectious immune-mediated mechanisms. However acute compressive neuropathy due to haemorrhage is not frequent and we could find no literature describing this

Case Report:

We report a case of acute compressive ulnar neuropathy due to peri neural hematoma, following an attempt at intravenous cannulation in the cubital fossa in a patient of dengue haemorrhagic fever with thrombocytopenia. Immediate fasciotomy and removal of haematoma was performed to relieve the symptoms.

Conclusion:

Compression neuropathies can be seen in dengue hemorrhagic fever and removal of compressing hematoma relieves symptoms