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PLoS Neglected Tropical Diseases May 2022Japanese Encephalitis (JE) is known for its high case fatality ratio (CFR) and long-term neurological sequelae. Over the years, efforts in JE treatment and control might...
BACKGROUND
Japanese Encephalitis (JE) is known for its high case fatality ratio (CFR) and long-term neurological sequelae. Over the years, efforts in JE treatment and control might change the JE fatality risk. However, previous estimates were from 10 years ago, using data from cases in the 10 years before this. Estimating JE disease severity is challenging because data come from countries with different JE surveillance systems, diagnostic methods, and study designs. Without precise and timely JE disease severity estimates, there is continued uncertainty about the JE disease burden and the effect of JE vaccination.
METHODOLOGY
We performed a systematic review to collate age-stratified JE fatality and morbidity data. We used a stepwise model selection with BIC as the selection criteria to identify JE CFR drivers. We used stacked regression, to predict country-specific JE CFR from 1961 to 2030. JE morbidity estimates were grouped from similar study designs to estimate the proportion of JE survivors with long-term neurological sequelae.
PRINCIPAL FINDINGS
We included 82 and 50 peer-reviewed journal articles published as of March 06 2021 for JE fatality and morbidity with 22 articles in both analyses. Results suggested overall JE CFR estimates of 26% (95% CI 22, 30) in 1961-1979, 20% (95% CI 17, 24) in 1980-1999, 14% (95% CI 11, 17) in 2000-2018, and 14% (95% CI 11, 17) in 2019-2030. Holding other variables constant, we found that JE fatality risk decreased over time (OR: 0.965; 95% CI: 0.947-0.983). Younger JE cases had a slightly higher JE fatality risk (OR: 1.012; 95% CI: 1.003-1.021). The odds of JE fatality in countries with JE vaccination is 0.802 (90% CI: 0.653-0.994; 95% CI: 0.62-1.033) times lower than the odds in countries without JE vaccination. Ten percentage increase in the percentage of rural population to the total population was associated with 15.35% (95% CI: 7.71, 22.57) decrease in JE fatality odds. Ten percentage increase in population growth rate is associated with 3.71% (90% CI: 0.23, 7.18; 95% CI: -0.4, 8.15) increase in JE fatality odds. Adjusting for the effect of year, rural population percent, age of JE cases, and population growth rate, we estimated that there was a higher odds of JE fatality in India compared to China. (OR: 5.46, 95% CI: 3.61-8.31). Using the prediction model we found that, in 2000-2018, Brunei, Pakistan, and Timor-Leste were predicted to have the highest JE CFR of 20%. Bangladesh, Guam, Pakistan, Philippines, and Vietnam had projected JE CFR over 20% for after 2018, whereas the projected JE CFRs were below 10% in China, Indonesia, Cambodia, Myanmar, Malaysia, and Thailand. For disability, we estimated that 36% (min-max 0-85) JE patients recovered fully at hospital discharge. One year after hospital discharge, 46% (min-max 0%-97%) JE survivors were estimated to live normally but 49% (min-max 3% - 86%)till had neurological sequelae.
CONCLUSION
JE CFR estimates were lower than 20% after 2000. Our study provides an updated estimation of CFR and proportion of JE cases with long-term neurological sequelae that could help to refine cost-benefit assessment for JE control and elimination programs.
Topics: China; Encephalitis, Japanese; Humans; Japanese Encephalitis Vaccines; Morbidity; Philippines; Thailand
PubMed: 35613183
DOI: 10.1371/journal.pntd.0010361 -
Human Vaccines & Immunotherapeutics 2014A number of Japanese encephalitis (JE) vaccines have been used for preventing Japanese encephalitis around the world. We here reviewed the immunogenicity and safety of... (Review)
Review
A number of Japanese encephalitis (JE) vaccines have been used for preventing Japanese encephalitis around the world. We here reviewed the immunogenicity and safety of the currently available Japanese encephalitis vaccines. We searched Pubmed, Embase, Web of Science, the Cochrane Library and other online databases up to March 25, 2014 for studies focusing on currently used JE vaccines in any language. The primary outcomes were the seroconversion rate against JEV and adverse events. Meta-analysis was performed for the primary outcome when available. A total of 51 articles were included. Studies were grouped on the basic types of vaccines. This systematic review led to 2 aspects of the conclusions. On one hand, all the currently available JE vaccines are safe and effective. On the other hand, the overall of JE vaccine evaluation is disorganized, the large variation in study designs, vaccine types, schedules, doses, population and few hand-to-hand trails, make direct comparisons difficult. In order to make a more evidence-based decision on optimizing the JE vaccine, it is warranted to standardize the JE vaccine evaluation research.
Topics: Animals; Clinical Trials as Topic; Humans; Japanese Encephalitis Vaccines; Vaccination
PubMed: 25668666
DOI: 10.4161/21645515.2014.980197 -
Brain and Behavior Feb 2022Japanese encephalitis (JE) is a potentially fatal viral infection with a wide range of manifestations and can also present with a variety of movement disorders (MD)... (Review)
Review
BACKGROUND
Japanese encephalitis (JE) is a potentially fatal viral infection with a wide range of manifestations and can also present with a variety of movement disorders (MD) including dystonia. Dystonic features in JE are uncommon. Here, we have tried to summarize the clinical features and management of dystonia among JE patients with a comprehensive literature search.
METHODS
Various databases, including PubMed, Embase, and Google Scholar, were searched against the predefined criteria using suitable keywords combination and boolean operations. Relevant information from observational and case studies was extracted according to the author, dystonic features, radiological changes in the brain scans, treatment options, and outcome wherever provided.
RESULT
We identified 19 studies with a total of 1547 JE patients, the diagnosis of which was confirmed by IgM detection in serum and/or cerebrospinal fluid in the majority of the patients (88.62%). 234 (15.13%) of JE patients had dystonia with several types of focal dystonia being present in 131 (55.98%) either alone or in combination. Neuroimaging showed predominant involvement of thalami, basal ganglia, and brainstem. Oral medications including anticholinergics, GABA agonists, and benzodiazepines followed by botulinum toxin were the most common treatment modalities.
CONCLUSION
Dystonia can be a disabling consequence of JE, and various available medical therapies can significantly improve the quality of life. Owing to insufficient studies on the assessment of dystonia associated with JE, longitudinal studies with a larger number of patients are warranted to further clarify the clinical course, treatment, and outcome of dystonia.
Topics: Dystonia; Dystonic Disorders; Encephalitis, Japanese; Humans; Movement Disorders; Quality of Life
PubMed: 35025122
DOI: 10.1002/brb3.2496 -
PLoS Neglected Tropical Diseases Feb 2022Japanese encephalitis (JE) virus (JEV) remains a leading cause of neurological infection across Asia. The high lethality of disease and absence of effective therapies... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Japanese encephalitis (JE) virus (JEV) remains a leading cause of neurological infection across Asia. The high lethality of disease and absence of effective therapies mean that standardised animal models will be crucial in developing therapeutics. However, published mouse models are heterogeneous. We performed a systematic review, meta-analysis and meta-regression of published JEV mouse experiments to investigate the variation in model parameters, assess homogeneity and test the relationship of key variables against mortality.
METHODOLOGY/ PRINCIPAL FINDINGS
A PubMed search was performed up to August 2020. 1991 publications were identified, of which 127 met inclusion criteria, with data for 5026 individual mice across 487 experimental groups. Quality assessment was performed using a modified CAMARADES criteria and demonstrated incomplete reporting with a median quality score of 10/17. The pooled estimate of mortality in mice after JEV challenge was 64.7% (95% confidence interval 60.9 to 68.3) with substantial heterogeneity between experimental groups (I^2 70.1%, df 486). Using meta-regression to identify key moderators, a refined dataset was used to model outcome dependent on five variables: mouse age, mouse strain, virus strain, virus dose (in log10PFU) and route of inoculation. The final model reduced the heterogeneity substantially (I^2 38.9, df 265), explaining 54% of the variability.
CONCLUSION/ SIGNIFICANCE
This is the first systematic review of mouse models of JEV infection. Better adherence to CAMARADES guidelines may reduce bias and variability of reporting. In particular, sample size calculations were notably absent. We report that mouse age, mouse strain, virus strain, virus dose and route of inoculation account for much, though not all, of the variation in mortality. This dataset is available for researchers to access and use as a guideline for JEV mouse experiments.
Topics: Animals; Disease Models, Animal; Encephalitis Virus, Japanese; Encephalitis, Japanese; Humans; Mice
PubMed: 35143497
DOI: 10.1371/journal.pntd.0010116 -
Oman Medical Journal Mar 2022Japanese encephalitis (JE) is one of the major mosquito-borne infectious diseases in the Western Pacific region, accounting for 20%-30% of mortality cases. The JE virus... (Review)
Review
OBJECTIVES
Japanese encephalitis (JE) is one of the major mosquito-borne infectious diseases in the Western Pacific region, accounting for 20%-30% of mortality cases. The JE virus (JEV) seroprevalence fluctuations indicate that continuous research is important for prevention and control activities. By mapping JEV seroprevalence by age stratification, the population profile for immunity and susceptibility can be identified to aid in vaccination program planning. Thus, this study aimed to determine the trend of age-specific JEV seroprevalence.
METHODS
We conducted a systematic review of all studies conducted on JEV seroprevalence between 2010 and 2019. The two search engines used were PubMed and Web of Science. Eligible criteria were set, and articles were screened according to the Preferred Reporting Items for Systematic Reviews and Meta- Analyses guidelines. Three investigators cross-checked all articles assigned. Data were extracted into an Excel sheet, and results were tabulated in tables and graphs accordingly.
RESULTS
Four studies from four countries (Taiwan, Sri Lanka, South Korea, and India) met the eligibility criteria. The papers showed an increasing trend of JEV seropositivity in all countries as their populations reach older age cohorts. Nonetheless, there were slight downtrend notches seen among young adults in Taiwan and India before increasing after reaching more mature ages. South Korea has the highest seroprevalence rate (97.8%-98.3%) among the compared countries. This is most likely because it was the earliest to introduce the JEV vaccine in 1967, which was later made mandatory in the early 1980s, while India has the lowest seroprevalence rate (12.9%-18.1%). Among the old vaccination-naïve population, seropositivity is commonly derived from natural infection.
CONCLUSIONS
Decreases in reported JE cases are mainly due to immunization. As JEV is expected to remain in nature and the zoonotic chains, the risk of infection will persist. Hence, it is important to apply JEV vaccination protocols in national immunization programs, prioritizing young children.
PubMed: 35356365
DOI: 10.5001/omj.2021.86 -
PLoS Neglected Tropical Diseases Mar 2015Japanese encephalitis virus (JEV) is an important cause of encephalitis in most of Asia, with high case fatality rates and often significant neurologic sequelae among... (Review)
Review
BACKGROUND
Japanese encephalitis virus (JEV) is an important cause of encephalitis in most of Asia, with high case fatality rates and often significant neurologic sequelae among survivors. The epidemiology of JE in the Philippines is not well defined. To support consideration of JE vaccine for introduction into the national schedule in the Philippines, we conducted a systematic literature review and summarized JE surveillance data from 2011 to 2014.
METHODS
We conducted searches on Japanese encephalitis and the Philippines in four databases and one library. Data from acute encephalitis syndrome (AES) and JE surveillance and from the national reference laboratory from January 2011 to March 2014 were tabulated and mapped.
RESULTS
We identified 29 published reports and presentations on JE in the Philippines, including 5 serologic surveys, 18 reports of clinical cases, and 8 animal studies (including two with both clinical cases and animal data). The 18 clinical studies reported 257 cases of laboratory-confirmed JE from 1972 to 2013. JE virus (JEV) was the causative agent in 7% to 18% of cases of clinical meningitis and encephalitis combined, and 16% to 40% of clinical encephalitis cases. JE predominantly affected children under 15 years of age and 6% to 7% of cases resulted in death. Surveillance data from January 2011 to March 2014 identified 73 (15%) laboratory-confirmed JE cases out of 497 cases tested.
SUMMARY
This comprehensive review demonstrates the endemicity and extensive geographic range of JE in the Philippines, and supports the use of JE vaccine in the country. Continued and improved surveillance with laboratory confirmation is needed to systematically quantify the burden of JE, to provide information that can guide prioritization of high risk areas in the country and determination of appropriate age and schedule of vaccine introduction, and to measure the impact of preventive measures including immunization against this important public health threat.
Topics: Adolescent; Antibodies, Viral; Child; Child, Preschool; Encephalitis Virus, Japanese; Encephalitis, Japanese; Female; Humans; Infant; Japanese Encephalitis Vaccines; Male; Philippines; Public Health; Seroepidemiologic Studies; Vaccination
PubMed: 25794009
DOI: 10.1371/journal.pntd.0003630 -
Journal of Travel Medicine Mar 2020Japanese encephalitis is a disease caused by a flavivirus which is transmitted by mosquitos in endemic countries. Considering the potentially severe outcomes of the...
Japanese encephalitis is a disease caused by a flavivirus which is transmitted by mosquitos in endemic countries. Considering the potentially severe outcomes of the disease, vaccination is recommended for those at risk of exposure. During recent years, IC51 (IXIARO®, JESPECT®, JEVAL®) has increasingly been used to protect travellers from Europe and the USA. However, no systematic review exists that summarizes the currently available evidence on the immunogenicity and safety of this vaccine. We conducted a systematic review on the immunogenicity and safety of IC51, using the databases PubMed, MEDLINE, EMBASE and ClinicalTrials.gov (search date: 31 August 2019). Data extracted from included studies were grouped by outcomes and stratified by population and setting. Risk of bias (ROB) was assessed using the RoB 2 tool for randomized controlled trials (RCTs) and ROBINS-I for non-randomized studies. Due to high heterogeneity, meta-analysis was not performed. A total of 32 studies from 16 countries met the inclusion criteria (15 RCTs, 17 non-randomized studies). ROB was serious or high in the majority of studies. Seroprotection rates ranged from 93 to 100% in adults (seven studies) and from 91 to 100% in children (four studies). In the study involving adults aged 64 years and older, seroprotection was 65% with higher rates in persons who were previously vaccinated against tick-borne encephalitis virus. Safety was investigated in 27 studies. Rates of serious adverse events were below 5% in all age groups, with the majority not being causally related to the vaccine. IC51 is a safe vaccine with good seroprotective abilities in persons aged >2 months to <64 years. The body of evidence, however, is weakened by a large amount of heterogeneity in study and clinical trial methodology. Further well-designed RCTs with special risk groups are needed.
Topics: Encephalitis, Japanese; Humans; Japanese Encephalitis Vaccines; Vaccination
PubMed: 32043122
DOI: 10.1093/jtm/taaa016 -
Vaccine Jun 2022The burden of Japanese encephalitis (JE) is substantial and is arguably one of the most serious viral encephalitic diseases with high case fatality and no specific... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
The burden of Japanese encephalitis (JE) is substantial and is arguably one of the most serious viral encephalitic diseases with high case fatality and no specific treatment. JE vaccines are the only available mean to prevent the disease; however, the long-term persistence of antibodies, boostability, and interchangeability between different vaccine classes are not well understood.
METHODS
To summarise the evidence, PubMed, Embase, and Cochrane CENTRAL were systematically searched from their inception to March 2021. Dose-response meta-analysis was utilised to synthesise the proportion of individuals who were seropositive over time after a primary vaccination course and a booster dose. Proportion meta-analysis was conducted to estimate the proportion of individuals who were seropositive as well as those who reported adverse events following a booster dose with a different vaccine class.
RESULTS
Of 1053 publications retrieved, 27 studies with 4,558 participants were included. Of these, 11 studies assessed persistence of antibodies, 14 studies boostability, and 8 vaccine class interchangeability. The pooled seropositivity, 1-year after primary vaccination was 83.4% (95 %CI 78.2-89.5%) and remained stable for up to 5 years (82.7%; 95 %CI 76.1-89.4%). Rapid anamnestic response was observed 10 days post-booster dose, the proportion of individuals who were seropositive reached 96.9% (95 %CI 95.9-97.8%) and remained > 95% for up to 6 years. Inactivated mouse brain-derived vaccines followed by a booster dose of a different vaccine class was effective (i.e. seropositive 99%) and well tolerated.
CONCLUSIONS
A booster dose after the primary vaccination is effective and further booster doses may be needed after 7 years. Inactivated mouse brain-derived vaccine followed by a booster with a newer vaccine class is effective and safe; although, there is a paucity of data related to newer classes of vaccines interchangeability.
Topics: Animals; Antibodies, Neutralizing; Antibodies, Viral; Encephalitis, Japanese; Humans; Immunization, Secondary; Japanese Encephalitis Vaccines; Mice; Vaccines, Inactivated
PubMed: 35568587
DOI: 10.1016/j.vaccine.2022.04.079 -
Preventive Veterinary Medicine Jun 2018Japanese encephalitis virus (JEV) is a virus of the Flavivirus genus that may result in encephalitis in human hosts. This vector-borne zoonosis occurs in Eastern and... (Review)
Review
Japanese encephalitis virus (JEV) is a virus of the Flavivirus genus that may result in encephalitis in human hosts. This vector-borne zoonosis occurs in Eastern and Southeastern Asia and an intentional or inadvertent introduction into the United States (US) would have major public health and economic consequences. The objective of this study was to gather, appraise, and synthesize primary research literature to identify and quantify vector and host competence for JEV, using a systematic review (SR) of the literature. After defining the research question, we performed a search in selected electronic databases and journals. The title and abstract of the identified articles were screened for relevance using a set of exclusion and inclusion criteria, and relevant articles were subjected to a risk of bias assessment, followed by data extraction. Data were extracted from 171 peer-reviewed articles. Most studies were observational studies (59.1%) and reported vector competence (60.2%). The outcome measures reported pertained to transmission efficiency, host preference, and vector susceptibility to infection within vector competence; and susceptibility to infection within host competence. Regarding vector competence, the proportion of JEV infection reported across all 149 mosquito species in all observational studies ranged from 0 to 100%. In experimental studies, infection, dissemination, and transmission rates varied between 0 and 100%. Minimum infection rates (MIR) varied between 0 and 333.3 per 1000 mosquitoes. Maximum likelihood estimation (MLE) values ranged from 0 to 53.8 per 1000 mosquitoes. The host species in which mosquitoes mostly fed consisted of pigs and cattle (total of 84 blood meals taken by mosquitoes from each of these host species). As for host competence, the proportion of JEV infection varied between 0 (in rabbits, reptiles, and amphibians) and 88.9% (cattle). This SR presents comprehensive data on JEV vector and host competence, which can be used to quantify risks associated with the introduction of JEV into the US.
Topics: Animals; Cattle; Culex; Disease Vectors; Encephalitis Virus, Japanese; Encephalitis, Japanese; Humans; Mosquito Vectors; Rabbits; Zoonoses
PubMed: 29685447
DOI: 10.1016/j.prevetmed.2018.03.018 -
Journal of Infection and Public Health Sep 2022Japanese encephalitis (JE) is a viral zoonotic disease that has been found in several countries of Asia and is responsible for high mortality and morbidity of men and... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Japanese encephalitis (JE) is a viral zoonotic disease that has been found in several countries of Asia and is responsible for high mortality and morbidity of men and animals in rural and sub-urban endemic areas due to the virus re-circulation among diverse hosts and vectors. The present study estimates the prevalence of the JE virus in the vector and animal population of the Asian continent using a systematic review and meta-analysis.
METHODS
The Cochran collaborators' Preferred Reporting Items for Systematic Reviews and Meta-Analysis [PRISMA] guidelines were used for systematic review and meta-analysis. The heterogeneity was observed in meta-regression analysis due to several factors including region, species, and different diagnostic assays used in various studies. Thus we did sensitivity and subgroup analysis.
RESULTS
The prevalence of the JE virus was calculated using a total sample size of 47,391. Subgroup analysis revealed the JE virus prevalence of 39% in the Southeast Asia region, followed by East Asia with 35% and South Asia with 15% prevalence. Hence, the overall pooled prevalence of the JE virus was 26% in the Asian continent.
CONCLUSIONS
The highest proportion of infection was found in pigs amongst all animals, reinforcing the fact that they can be used as sentinels to predict outbreaks in humans. The findings of this study will enable researchers and policymakers in better understanding the disease's spatial and temporal distribution, as well as in creating and implementing location-specific JE prevention and control measures.
Topics: Animals; Culicidae; Encephalitis Virus, Japanese; Encephalitis, Japanese; Humans; Male; Mosquito Vectors; Prevalence; Swine
PubMed: 35914358
DOI: 10.1016/j.jiph.2022.07.010