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Vaccine Jul 2021Annually more than 100,000 Japanese encephalitis (JE) cases and 25,000 deaths worldwide are caused by JE virus infection. More than 15 JE vaccines are currently in use... (Meta-Analysis)
Meta-Analysis Review
INTRODUCTION
Annually more than 100,000 Japanese encephalitis (JE) cases and 25,000 deaths worldwide are caused by JE virus infection. More than 15 JE vaccines are currently in use worldwide. It is unknown whether any of the vaccines is superior to the others in terms of immunogenicity and safety.
METHODS
Four databases were systematically searched for randomised controlled trials that compared two or more types of JE vaccines. Vaccines were classified into four classes: inactivated mouse brain-derived (oldest class), inactivated Vero cell, live chimeric, and live attenuated. Network meta-analysis was used to generate mixed effect estimates against inactivated mouse brain-derived vaccines for seroconversion, and against placebo for adverse event (AE) and severe adverse event (SAE).
RESULTS
23 studies (38,496 participants) were included. All newer vaccine classes had better immunogenicity, the difference was statistically significant for inactivated Vero cell (OR = 2.98; 95 %CI: 1.02-8.65) and live chimeric (OR = 5.93; 95 %CI: 1.73-20.32) vaccines. Inactivated mouse-derived vaccines had the highest odds for AEs (OR = 2.27; 95 %CI: 1.59-3.23), the odds of AE of newer vaccines was not different to placebo. There was no difference in SAEs across vaccine classes.
CONCLUSIONS
All newer JE vaccines have comparable safety profiles, live chimeric and inactivated Vero cell vaccines are the most immunogenic among the newer vaccine classes.
Topics: Animals; Antibodies, Viral; Encephalitis Virus, Japanese; Encephalitis, Japanese; Japanese Encephalitis Vaccines; Mice; Network Meta-Analysis; Vaccination; Vaccines, Attenuated; Vaccines, Inactivated
PubMed: 34175128
DOI: 10.1016/j.vaccine.2021.06.023 -
International Journal of Infectious... Feb 2018Countries with strong vaccination programmes, including the Republic of Korea, have experienced changes in the epidemiology of Japanese encephalitis (JE), with an... (Review)
Review
BACKGROUND
Countries with strong vaccination programmes, including the Republic of Korea, have experienced changes in the epidemiology of Japanese encephalitis (JE), with an increase in cases seen among adults. However, the reasons for this increase are not clearly understood. This study describes the change in age-specific JE virus (JEV) seroprevalence over time in Korea, with a view to understanding this transition.
METHODS
A search of Embase, MEDLINE, PubMed, KoreaMed, Korea Education and Research Information Service, National Library of Korea, and the Seoul National University Medical Library was conducted using the keywords 'Japanese encephalitis' combined with 'Korea', 'seroprevalence', 'seropositivity', 'seroepidemiology', 'serosurvey', 'immunity', and 'antibody'.
RESULTS
Eighteen studies published between 1946 and 2012 were retrieved. In 1946, seropositivity was 51% in the 1-10 years age group, 79% in those aged 11-20 years, and 94% in those ≥61 years of age. In the 1970s, seropositivity in children and adolescents was low (10-59%); seropositivity in this group increased to 90-92% in 1984-1985, and increased further to 98% in 2012. Seropositivity among adults aged 41-50 years and 51-60 years in the 2010s ranged between 83.1% and 97.9% and between 77.5% and 98.3%, respectively.
CONCLUSIONS
The implementation of the universal JE vaccination programme in the 1980s has increased the seroprevalence of JEV in Korea, especially in children who are targeted for vaccination.
Topics: Encephalitis, Japanese; Humans; Republic of Korea; Seroepidemiologic Studies
PubMed: 29183842
DOI: 10.1016/j.ijid.2017.11.023 -
PLoS Neglected Tropical Diseases Oct 2022The detection of the first cases of transfusion-transmitted West Nile virus in 2002 posed a new challenge for transfusion safety. Institutions like the World Health...
BACKGROUND
The detection of the first cases of transfusion-transmitted West Nile virus in 2002 posed a new challenge for transfusion safety. Institutions like the World Health Organization have stated that blood transfusion centers need to know the epidemiology of the different emerging infectious agents and their impact on blood transfusion. The aim of the study is to review the published cases of arbovirus transmission through transfusion of blood or blood components and to analyze their main clinical and epidemiological characteristics.
MATERIAL AND METHODS
Systematic literature searches were conducted in MEDLINE, Embase and Scopus. Pairs of review authors selected a variety of scientific publications reporting cases of transfusion-transmitted arboviruses. Main clinical and epidemiological characteristics were reviewed of the cases described. The study protocol was registered in PROSPERO CRD42021270355.
RESULTS
A total of 74 cases of transfusion-transmitted infections were identified from 10 arboviruses: West Nile virus (n = 42), dengue virus (n = 18), Zika virus (n = 3), yellow fever vaccine virus (n = 3), tick-borne encephalitis virus (n = 2), Japanese encephalitis virus (n = 2), Powassan virus (n = 1), St. Louis encephalitis virus (n = 1), Ross River virus (n = 1) and Colorado tick fever virus (n = 1). The blood component most commonly involved was red blood cells (N = 35, 47.3%; 95% confidence interval [CI] 35.9% to 58.7%). In 54.1% (N = 40; 95% CI: 42.7%-65.47%) of the cases, the recipient was immunosuppressed. Transmission resulted in death in 18.9% (N = 14; 95% CI: 10.0%-27.8%) of the recipients. In addition, 18 additional arboviruses were identified with a potential threat to transfusion safety.
DISCUSSION
In the last 20 years, the number of published cases of transfusion-transmitted arboviruses increased notably, implicating new arboviruses. In addition, a significant number of arboviruses that may pose a threat to transfusion safety were detected. In the coming years, it is expected that transmission of arboviruses will continue to expand globally. It is therefore essential that all responsible agencies prepare for this potential threat to transfusion safety.
Topics: Humans; Arbovirus Infections; Arboviruses; Blood Transfusion; West Nile virus; Yellow Fever Vaccine; Zika Virus; Zika Virus Infection
PubMed: 36201547
DOI: 10.1371/journal.pntd.0010843 -
Scientific Reports Jan 2023The increasing trend of mosquito-borne pathogens demands more accurate global estimations of infection and transmission risks between mosquitoes. Here, we systematically...
The increasing trend of mosquito-borne pathogens demands more accurate global estimations of infection and transmission risks between mosquitoes. Here, we systematically review field and laboratory studies to assess the natural field infection and experimental laboratory transmission risk in Culex mosquitoes. We studied four worldwide flaviviruses: West Nile, Usutu, Japanese encephalitis, and St. Louis encephalitis, belonging to the Japanese encephalitis Serocomplex (JES). The PRISMA statement was carried out for both approaches. The Transmission-Infection Risk of the diverse mosquito species for the different viruses was estimated through seven variables. We considered 130 and 95 articles for field and experimental approach, respectively. We identified 30 species naturally infected, and 23 species capable to transmit some of the four flaviviruses. For the JES, the highest Transmission-Infection Risk estimate was recorded in Culex quinquefasciatus (North America). The maximum Infection-Transmission Risk values for West Nile was Culex restuans, for Usutu it was Culex pipiens (Europe), for St. Louis encephalitis Culex quinquefasciatus (North America), and for Japanese encephalitis Culex gelidus (Oceania). We conclude that on a worldwide scale, a combination of field and experimental data offers a better way of understanding natural infection and transmission risks between mosquito populations.
Topics: Animals; Encephalitis Viruses, Japanese; Mosquito Vectors; West Nile virus; West Nile Fever; Encephalitis, St. Louis; Encephalitis, Japanese; Flavivirus; Culicidae; Culex
PubMed: 36609450
DOI: 10.1038/s41598-022-27236-1 -
Human Vaccines & Immunotherapeutics 2015Japanese encephalitis virus (JEV), a leading cause of Japanese encephalitis (JE) in children and adults, is a major public health problem in Asian countries. This study... (Meta-Analysis)
Meta-Analysis Review
Japanese encephalitis virus (JEV), a leading cause of Japanese encephalitis (JE) in children and adults, is a major public health problem in Asian countries. This study reports a meta-analysis of the immunogenicity and safety of vaccines used to protect infants or children from JE. Three types of JE vaccine were examined, namely, Japanese encephalitis live-attenuated vaccine (JEV-L), Japanese encephalitis inactivated vaccine (Vero cell) (JEV-I(Vero)), and Japanese encephalitis inactivated vaccine (primary hamster kidney cell) (JEV-I(PHK)). These vaccines are used to induce fundamental immunity against JE; however, few studies have compared their immunogenicity and safety in infants and young children less than 2 years of age. Data were obtained by searching 5 databases: Web of Science, PubMed, China National Knowledge Infrastructure, the China Wanfang database, and the Cochrane database. Fifteen articles were identified and scored using the Jadad score for inclusion in the meta-analysis. Random effect models were used to calculate the pooled seroconversion rate and adverse reaction rate when tests for heterogeneity were significant. The results showed that the pooled seroconversion rate for JEV-I(PHK) (62.23%) was lower than that for JEV-I(Vero) (86.49%) and JEV-L (83.52%), and that the pooled adverse reaction rate for JEV-L (18.09%) was higher than that for JEV-I(PHK) (10.08%) and JEV-I(Vero) (12.49%). The pooled relative risk was then calculated to compare the seroconversion and adverse reaction rates. The results showed that JEV-I(Vero) and JEV-L were more suitable than JEV-I(PHK) for inducing fundamental immunity to JE in infants and children less than 2 years of age.
Topics: Antibodies, Viral; Asia; Drug-Related Side Effects and Adverse Reactions; Encephalitis, Japanese; Humans; Japanese Encephalitis Vaccines; Pacific Islands; Vaccines, Attenuated; Vaccines, Inactivated
PubMed: 25915588
DOI: 10.1080/21645515.2015.1011996 -
PloS One 2018Japanese encephalitis virus (JEV) is a major cause of encephalitis in Asia, and the commonest cause of mosquito-borne encephalitis worldwide. Detection of JEV RNA... (Review)
Review
Development of an improved RT-qPCR Assay for detection of Japanese encephalitis virus (JEV) RNA including a systematic review and comprehensive comparison with published methods.
BACKGROUND
Japanese encephalitis virus (JEV) is a major cause of encephalitis in Asia, and the commonest cause of mosquito-borne encephalitis worldwide. Detection of JEV RNA remains challenging due to the characteristic brief and low viraemia, with 0-25% of patients positive, and the mainstay of diagnosis remains detection of anti-JEV IgM antibody.
METHODS
We performed a systematic review of published RT-PCR protocols, and evaluated them in silico and in vitro alongside new primers and probes designed using a multiple genome alignment of all JEV strains >9,000nt from GenBank, downloaded from the NCBI website (November 2016). The new assays included pan-genotype and genotype specific assays targeting genotypes 1 and 3.
RESULTS
Ten RT-qPCR assays were compared, a pre-existing in-house assay, three published assays and six newly designed assays, using serial RNA dilutions. We selected three assays, one published and two novel assays, with the lowest limit of detection (LOD) for further optimisation and validation. One of the novel assays, detecting NS2A, showed the best results, with LOD approximately 4 copies/ reaction, and no cross-reaction on testing closely related viruses in the JEV serocomplex, West Nile Virus and St. Louis Virus. The optimised assays were validated in consecutive patients with central nervous system infections admitted to hospitals in Laos, testing paired CSF and serum samples.
CONCLUSIONS
We succeeded in developing a JEV specific RT-qPCR assay with at least 1 log10 improved sensitivity as compared to existing assays. Further evaluation is required, field-testing the assay in a larger group of patients.
Topics: Asia; Encephalitis Virus, Japanese; Encephalitis, Japanese; Humans; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction
PubMed: 29570739
DOI: 10.1371/journal.pone.0194412 -
Parasites & Vectors Sep 2017Japanese encephalitis (JE) is a zoonosis in Southeast Asia vectored by mosquitoes infected with the Japanese encephalitis virus (JEV). Japanese encephalitis is... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Japanese encephalitis (JE) is a zoonosis in Southeast Asia vectored by mosquitoes infected with the Japanese encephalitis virus (JEV). Japanese encephalitis is considered an emerging exotic infectious disease with potential for introduction in currently JEV-free countries. Pigs and ardeid birds are reservoir hosts and play a major role on the transmission dynamics of the disease. The objective of the study was to quantitatively summarize the proportion of JEV infection in vectors and vertebrate hosts from data pertaining to observational studies obtained in a systematic review of the literature on vector and host competence for JEV, using meta-analyses.
METHODS
Data gathered in this study pertained to three outcomes: proportion of JEV infection in vectors, proportion of JEV infection in vertebrate hosts, and minimum infection rate (MIR) in vectors. Random-effects subgroup meta-analysis models were fitted by species (mosquito or vertebrate host species) to estimate pooled summary measures, as well as to compute the variance between studies. Meta-regression models were fitted to assess the association between different predictors and the outcomes of interest and to identify sources of heterogeneity among studies. Predictors included in all models were mosquito/vertebrate host species, diagnostic methods, mosquito capture methods, season, country/region, age category, and number of mosquitos per pool.
RESULTS
Mosquito species, diagnostic method, country, and capture method represented important sources of heterogeneity associated with the proportion of JEV infection; host species and region were considered sources of heterogeneity associated with the proportion of JEV infection in hosts; and diagnostic and mosquito capture methods were deemed important contributors of heterogeneity for the MIR outcome.
CONCLUSIONS
Our findings provide reference pooled summary estimates of vector competence for JEV for some mosquito species, as well as of sources of variability for these outcomes. Moreover, this work provides useful guidelines when interpreting vector and host infection proportions or prevalence from observational studies, and contributes to further our understanding of vector and vertebrate host competence for JEV, elucidating information on the relative importance of vectors and hosts on JEV introduction and transmission.
Topics: Animals; Culex; Encephalitis Virus, Japanese; Encephalitis, Japanese; Humans; Mosquito Vectors; Observational Studies as Topic; Regression Analysis; Seasons; Swine; Vertebrates; Zoonoses
PubMed: 28882172
DOI: 10.1186/s13071-017-2354-7 -
Bulletin of the World Health... Oct 2011To update the estimated global incidence of Japanese encephalitis (JE) using recent data for the purpose of guiding prevention and control efforts. (Review)
Review
OBJECTIVE
To update the estimated global incidence of Japanese encephalitis (JE) using recent data for the purpose of guiding prevention and control efforts.
METHODS
Thirty-two areas endemic for JE in 24 Asian and Western Pacific countries were sorted into 10 incidence groups on the basis of published data and expert opinion. Population-based surveillance studies using laboratory-confirmed cases were sought for each incidence group by a computerized search of the scientific literature. When no eligible studies existed for a particular incidence group, incidence data were extrapolated from related groups.
FINDINGS
A total of 12 eligible studies representing 7 of 10 incidence groups in 24 JE-endemic countries were identified. Approximately 67,900 JE cases typically occur annually (overall incidence: 1.8 per 100,000), of which only about 10% are reported to the World Health Organization. Approximately 33,900 (50%) of these cases occur in China (excluding Taiwan) and approximately 51,000 (75%) occur in children aged 0-14 years (incidence: 5.4 per 100,000). Approximately 55,000 (81%) cases occur in areas with well established or developing JE vaccination programmes, while approximately 12,900 (19%) occur in areas with minimal or no JE vaccination programmes.
CONCLUSION
Recent data allowed us to refine the estimate of the global incidence of JE, which remains substantial despite improvements in vaccination coverage. More and better incidence studies in selected countries, particularly China and India, are needed to further refine these estimates.
Topics: Adolescent; Age Factors; Child; Child Welfare; Child, Preschool; Disease Outbreaks; Encephalitis, Japanese; Female; Global Health; Humans; Incidence; Infant; Infant, Newborn; Japanese Encephalitis Vaccines; Male; Pediatrics; Population Surveillance; Risk Assessment; World Health Organization
PubMed: 22084515
DOI: 10.2471/BLT.10.085233 -
International Journal of Infectious... Jun 2022Japanese encephalitis virus (JEV) and dengue virus (DENV) represent important causes of encephalitis in Asia. Brain imaging may provide diagnostic clues about the... (Review)
Review
OBJECTIVES
Japanese encephalitis virus (JEV) and dengue virus (DENV) represent important causes of encephalitis in Asia. Brain imaging may provide diagnostic clues about the etiology of infectious encephalitis. We performed a systematic review of brain imaging findings in Japanese encephalitis (JE) and DENV neurological infection (dengue) to identify characteristic lesions.
METHODOLOGY
Five databases were searched. We included all study types and imaging techniques. Laboratory methods were categorized using diagnostic confidence levels. Imaging data were synthesized, and focal findings are presented as proportions for JE and dengue and for subgroups based on diagnostic confidence.
PRINCIPAL FINDINGS
Thalamic lesions were the most reported magnetic resonance imaging finding in both diseases but appeared to occur more often in JE (74% in 23 studies) than dengue (29.4% in 58 studies). In cases diagnosed with antigen or nucleic acid tests, thalamic lesions were reported frequently in both JE (76.5% in 17 studies) and dengue (65.2% in 23 studies).
SIGNIFICANCE
The results suggest that thalamic lesions frequently occur in both JE and dengue encephalitis. No radiological findings were found to be pathognomonic of either disease. Although brain imaging may support a diagnosis, laboratory confirmation with highly specific tests remains crucial.
Topics: Antibodies, Viral; Communicable Diseases; Dengue; Dengue Virus; Encephalitis Virus, Japanese; Encephalitis, Japanese; Humans; Neuroimaging
PubMed: 35283297
DOI: 10.1016/j.ijid.2022.03.010 -
ELife May 2020Japanese encephalitis (JE) is a mosquito-borne disease, known for its high mortality and disability rate among symptomatic cases. Many effective vaccines are available...
Japanese encephalitis (JE) is a mosquito-borne disease, known for its high mortality and disability rate among symptomatic cases. Many effective vaccines are available for JE, and the use of a recently developed and inexpensive vaccine, SA 14-14-2, has been increasing over the recent years particularly with Gavi support. Estimates of the local burden and the past impact of vaccination are therefore increasingly needed, but difficult due to the limitations of JE surveillance. In this study, we implemented a mathematical modelling method (catalytic model) combined with age-stratifed case data from our systematic review which can overcome some of these limitations. We estimate in 2015 JEV infections caused 100,308 JE cases (95% CI: 61,720-157,522) and 25,125 deaths (95% CI: 14,550-46,031) globally, and that between 2000 and 2015 307,774 JE cases (95% CI: 167,442-509,583) were averted due to vaccination globally. Our results highlight areas that could have the greatest benefit from starting vaccination or from scaling up existing programs and will be of use to support local and international policymakers in making vaccine allocation decisions.
Topics: Encephalitis, Japanese; Endemic Diseases; Global Burden of Disease; Humans; Japanese Encephalitis Vaccines; Vaccination
PubMed: 32450946
DOI: 10.7554/eLife.51027