Clinical predictors of Japanese encephalitis

Profile of Acute Encephalitis Syndrome Patients from South India

Introduction

Encephalitis is a major public health problem worldwide that causes huge emotional and economic loss to humanity. Encephalitis, being a serious illness, affects people of all ages. The aim is to describe the sociodemographic, clinical, etiological, and neuroimaging profile among 101 acute encephalitis syndrome (AES) patients visiting a tertiary neuro-specialty care hospital in India.

Methods

Record review of medical records of all patients attending neurology emergency and outpatient services at NIMHANS Hospital, diagnosed with AES in 2019, was conducted. Data were collected using standardized data collection forms for all cases in the study. Descriptive analyses (mean and standard deviation for continuous variables and proportions for categorical variables) were conducted. The Chi-square test/Fisher's exact test was used for the comparison of independent groups for categorical variables, and t-test for comparing means for continuous variables.

Results

About 42.6% of AES patients had viral etiology, while in 57.4%, etiology was not ascertained. Common presenting symptoms were fever (96%), altered sensorium (64.4%), seizures (70.3%), headache (42.6%), and vomiting (27.7%). Herpes simplex was the most common (21.8%) identified viral encephalitis, followed by chikungunya (5%), arboviruses (chikungunya and dengue) (4%), Japanese encephalitis (4%), rabies (3%), dengue (1%), and varicella virus (1%). About 40% of AES patients showed cerebrospinal fluid pleocytosis (44%), increased protein (39.6%), abnormal computed tomography brain (44.6%), and magnetic resonance imaging abnormalities (41.6%).

Conclusion

The study highlights the need to ascertain etiology and importance of evidence-based management of AES patients. A better understanding of opportunities and limitations in the management and implementation of standard laboratory and diagnostic algorithms can favor better diagnosis and management of AES.

A need to raise the bar - A systematic review of temporal trends in diagnostics for Japanese encephalitis virus infection, and perspectives for future research

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Japanese encephalitis virus (JEV) remains a leading cause of neurological infection in Asia.

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A systematic review identified 20,212 published human cases of laboratory-confirmed JEV infections from 205 studies.

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15,167 (75%) of cases were confirmed with the lowest confidence diagnostic test, i.e., level 3 or 4, or level 4.

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Only 109 (53%) of the studies reported contemporaneous testing for dengue-specific antibodies.

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A fundamental pre-requisite for the control of JE is lacking — that of a simple and specific diagnostic procedure that can be adapted for point-of-care tests and readily used throughout JE endemic regions of the world.

Objective

Japanese encephalitis virus infection (JE) remains a leading cause of neurological disease in Asia, mainly involving individuals living in remote areas with limited access to treatment centers and diagnostic facilities. Laboratory confirmation is fundamental for the justification and implementation of vaccination programs. We reviewed the literature on historical developments and current diagnostic capability worldwide, to identify knowledge gaps and instill urgency to address them.

Methods

Searches were performed in Web of Science and PubMed using the term 'Japanese encephalitis' up to 13th October 2019. Studies reporting laboratory-confirmed symptomatic JE cases in humans were included, and data on details of diagnostic tests were extracted. A JE case was classified according to confirmatory levels (Fischer et al., 2008; Campbell et al., 2011; Pearce et al., 2018; Heffelfinger et al., 2017), where level 1 represented the highest level of confidence.

Findings

20,212 published JE cases were identified from 205 studies. 15,167 (75%) of these positive cases were confirmed with the lowest-confidence diagnostic tests (level 3 or 4, or level 4). Only 109 (53%) of the studies reported contemporaneous testing for dengue-specific antibodies.

Conclusion

A fundamental pre-requisite for the control of JEV is lacking — that of a simple and specific diagnostic procedure that can be adapted for point-of-care tests and readily used throughout JE-endemic regions of the world.

Understanding and managing acute encephalitis

Encephalitis is an important cause of morbidity, mortality, and permanent neurologic sequelae  globally. Causes are diverse and include viral and non-viral infections of the brain as well as autoimmune processes. In the West, the autoimmune encephalitides are now more common than any single infectious cause, but, in Asia, infectious causes are still more common. In 2006, the World Health Organization coined the term "acute encephalitis syndrome", which simply means acute onset of fever with convulsions or altered consciousness or both. In 2013, the International Encephalitis Consortium set criteria for diagnosis of encephalitis on basis of clinical and laboratory features. The most important infectious cause in the West is herpes simplex virus, but globally Japanese encephalitis (JE) remains the single largest cause. Etiologic diagnosis is difficult because of the large number of agents that can cause encephalitis. Also, the responsible virus may be detectable only in the brain and is either absent or transiently found in blood or cerebrospinal fluid (CSF). Virological diagnosis is complex, expensive, and time-consuming. Different centres could make their own algorithms for investigation in accordance with the local etiologic scenarios. Magnetic resonance imaging (MRI) and electroencephalography are specific for few agents. Clinically, severity may vary widely. A severe case may manifest with fever, convulsions, coma, neurologic deficits, and death. Autoimmune encephalitis (AIE)  includes two major categories: (i) classic paraneoplastic limbic encephalitis (LE) with autoantibodies against intracellular neuronal antigens (Eg: Hu and Ma2) and (ii) new-type AIE with autoantibodies to neuronal surface or synaptic antigens (Eg: anti-N-methyl-D-aspartate receptor). AIE has prominent psychiatric manifestations: psychosis, aggression, mutism, memory loss, euphoria, or fear. Seizures, cognitive decline, coma, and abnormal movements are common. Symptoms may fluctuate rapidly. Treatment is largely supportive. Specific treatment is available for herpesvirus group and non-viral infections. Various forms of immunotherapy are used for AIE.

Potential chemotherapeutic targets for Japanese encephalitis: current status of antiviral drug development and future challenges

INTRODUCTION

Japanese encephalitis (JE) remains a public health threat in Asia. Although several vaccines have been licensed, ∼ 67,900 cases of the disease are estimated to occur annually, probably because the vaccine coverage is low. Therefore, effective antiviral drugs are required to control JE. However, no licensed anti-JE drugs are available, despite extensive efforts to develop them.

AREAS COVERED

We provide a general overview of JE and JE virus, including its transmission cycle, distribution, structure, replication machinery, immune evasion mechanisms and vaccines. The current situation in antiviral drug development is then reviewed and future perspectives are discussed.

EXPERT OPINION

Although the development of effective anti-JE drugs is an urgent issue, only supportive care is currently available. Recent progress in our understanding of the viral replication machinery and immune evasion strategies has identified new targets for anti-JE drug development. To date, most candidate drugs have only been evaluated in single-drug formulations, and efficient drug delivery to the CNS has virtually not been considered. However, an effective anti-JE treatment is expected to be achieved with multiple-drug formulations and a targeted drug delivery system in the near future.

[Flaviviruses]

Family Flaviviridae genus flavivirus contains numerous pathogenic viruses such as Japanese encephalitis virus, dengue virus, West Nile virus, etc, which cause public health problems in the world. Since many mammals and birds can act as amplifying hosts and reservoir hosts in nature and those viruses are transmitted by haematophagous mosquitoes or ticks, those viruses could not be eradicated from the nature. In the recent few decades, the viral replication mechanism and the ultrastructure of viral proteins as well as the viral immune evasion mechanism have been elucidated extensively, leading to develop novel types of antivirals and vaccines. In this review, the flavivirus nature and epidemiology, replication mechanism, immune response and immune evasion, and antivirals and vaccines against flaviviruses were described.

Structure-based virtual screening for novel inhibitors of Japanese encephalitis virus NS3 helicase/nucleoside triphosphatase

Japanese encephalitis (JE) is a significant cause of human morbidity and mortality throughout Asia and Africa. Vaccines have reduced the incidence of JE in some countries, but no specific antiviral therapy is currently available. The NS3 protein of Japanese encephalitis virus (JEV) is a multifunctional protein combining protease, helicase and nucleoside 5′‐triphosphatase (NTPase) activities. The crystal structure of the catalytic domain of this protein has recently been solved using a roentgenographic method. This enabled structure‐based virtual screening for novel inhibitors of JEV NS3 helicase/NTPase. The aim of the present research was to identify novel potent medicinal substances for the treatment of JE. In the first step of studies, the natural ligand ATP and two known JEV NS3 helicase/NTPase inhibitors were docked to their molecular target. The refined structure of the enzyme was used to construct a pharmacophore model for JEV NS3 helicase/NTPase inhibitors. The freely available ZINC database of lead‐like compounds was then screened for novel inhibitors. About 1 161 000 compounds have been screened and 15 derivatives of the highest scores have been selected. These compounds were docked to the JEV NS3 helicase/NTPase to examine their binding mode and verify screening results by consensus scoring procedure.

Japanese encephalitis revisited

Japanese encephalitis (JE) is a major public health problem in Southeast Asia with around 50,000 cases and 10,000 deaths per year affecting essentially children below 10 years of age. The JE virus has shown a tendency to extend to other geographic regions. JE may cause severe encephalitis and survivors are frequently left with serious neurological lesions. In the absence of an effective antiviral treatment, prevention constitutes the best defense against this disease. Besides the implementation of vector control, immunization by vaccination is available. Vector control is expensive and difficult to implement on a large scale, leaving vaccination as the best means for mass campaigns. Recent progress in the development of live attenuated vaccines has given hope of an effective vaccine, which is both easy to use and inexpensive for large scale programs.

Clinical features in children hospitalized during the 2005 epidemic of Japanese encephalitis in Uttar Pradesh, India

BACKGROUND

Japanese encephalitis is a disease that affects the rural poor in Asia. In August-September 2005, a severe epidemic of Japanese encephalitis occurred in Uttar Pradesh, one of India's poorest states.

METHODS

Children admitted to the King George Medical University hospital (Lucknow, Uttar Pradesh, India) with acute febrile encephalopathy (defined as fever plus encephalopathy of <or=2 weeks' duration) from July to October 2005 underwent ELISA for Japanese encephalitis virus immunoglobulin M in cerebrospinal fluid or serum on hospital admission. Clinicolaboratory features of patients with positive test results were recorded.Results. Of the 223 children tested, 77 had positive results for Japanese encephalitis immunoglobulin M. Patients were from 18 districts of Uttar Pradesh. All but 1 were from rural areas, and none were <2 years of age. The prodromal period was very short (mean+/-standard deviation, 2.61+/-2.23 days). Convulsions were present in 76 patients (98.7%). The mean (+/- standard deviation) Glasgow Coma Scale score was 7.4+/-2.7. Generalized hypertonia was found in 39 patients (50.6%), and focal deficits were found in 35 patients (45.4%), including 19 cases of monoparesis and 16 cases of hemiparesis. Gastric hemorrhage was found in 42 patients (54.5%). Extrapyramidal features were found in 24 (31.1%), a hyperepneic breathing pattern was found in 20 (26%), and thrombocytopenia was found in 5 (15.6%) of 32 patients. The mean cerebrospinal fluid cell count was 48.3 cells/mm(3). The serum bilirubin level was normal in all patients, but the aspartate aminotransferase level was elevated in all 21 patients (100%) tested and the alanine aminotranferase level was elevated in 25 (47.2%) of 53 patients. In-hospital mortality was 34%.

CONCLUSIONS

Clinical features of Japanese encephalitis were severe. Derangements in liver function and thrombocytopenia were found in a significant proportion of patients. These findings were not highlighted during earlier epidemics of the illness and could suggest a possible mutation of the virus towards other flaviviruses.

New initiatives for the control of Japanese encephalitis by vaccination: minutes of a WHO/CVI meeting, Bangkok, Thailand, 13-15 October 1998

Japanese encephalitis (JE) is a leading cause of viral encephalitis in Asia that, in several countries, has been controlled effectively through national vaccine programs. However, in recent years, transmission has been recognized or has intensified in new locations where the available vaccines are either unaffordable or unlicensed. In addition, the near-eradication of poliomyelitis from Asia has elevated JE in the public health agenda of preventable childhood diseases, and surveillance of acute neurological infections to confirm polio eradication, simultaneously, has led to a greater awareness of the disease burden attributable to JE. The only internationally licensed JE vaccine, an inactivated mouse-brain derived vaccine, is efficacious but is problematic from the perspectives of reactogenicity, requirement for numerous doses, cost and reliance on a neurological tissue substrate. A live-attenuated vaccine distributed only in China also is efficacious and requires fewer doses; however, production and regulatory standards are unresolved. Several approaches toward developing novel JE vaccines that could fill the gap in JE vaccine need are under pursuit. The minutes and recommendations of a meeting of experts to discuss these issues, jointly sponsored by the World Health Organization and the Children's Vaccine Initiative in Bangkok, Thailand, 13-15 October, 1998, are presented.

Viral encephalitis of public health significance in India: current status

Japanese encephalitis (JE) and rabies are 2 viral encephalitis that are of public health importance in India. JE is a zoonosis with the primary cycle occurring in arthropods (mosquito vectors) and vertebrate animals (primarily the pig), man being only an incidental 'dead end' host. Out-breaks have been seen in most parts of India except the north west. The disease presents with a prodromal stage, an acute encephalitic stage with coma, convulsions and variable deficits and a convalescent stage. Diagnosis can be made by viral isolation from CSF or brain, or serologic tests such as haemagglutination inhibition test and IgM antibody capture ELISA in CSF and blood. There is no specific treatment. Mortality ranges from 20-50% and almost half the survivors have sequelae. The most effective control measure besides control of mosquitos is vaccination. A killed mouse brain vaccine is being prepared in India and is safe and effective but expensive. Rabies is a highly fatal encephalomyelitis primarily occurring in urban dogs and wild animals especially canines. It is endemic in India and affects an estimated 3 per 100,000 persons annually. The patient initially may display bizarre combative behaviour. The disease can be effectively prevented by post exposure vaccination. The nervous tissue vaccine is no longer recommended because of unacceptable neurotoxicity. Three cell culture vaccines are presently available with about equal efficacy.