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Human Vaccines & Immunotherapeutics Jan 2018Japanese encephalitis (JE) is the most commonly diagnosed viral encephalitis in Asia. JE is caused by a virus called JE virus (JEV), a member of the genus Flavivirus,... (Review)
Review
Japanese encephalitis (JE) is the most commonly diagnosed viral encephalitis in Asia. JE is caused by a virus called JE virus (JEV), a member of the genus Flavivirus, family Flaviviridae, and is transmitted by Culex mosquitoes. Neutralising antibody to JEV protects against JE, and can be induced by vaccination. JE is a potential threat to travellers to endemic areas, which are most of South and Southeast Asia and some Pacific Islands. The risk of JE can be expected to increase with increasing mosquito exposure and time spent in regions and seasons of active transmission. JE is very rare in travellers, but mortality is high, around 1 in 3, and there is a high rate of lasting neurological damage. JE can therefore be a profoundly life changing event for a traveller. Travellers and their healthcare providers need to balance the low risk of disease against the very high severity of disease if it does occur. In order to make an informed decision, the severity of JE disease should be carefully explained to travellers to Asia.
Topics: Asia; Decision Making; Encephalitis Virus, Japanese; Encephalitis, Japanese; Endemic Diseases; Humans; Japanese Encephalitis Vaccines; Risk Assessment; Seasons; Severity of Illness Index; Travel-Related Illness; Vaccination
PubMed: 29244615
DOI: 10.1080/21645515.2017.1380756 -
Human Vaccines & Immunotherapeutics Nov 2021Japanese encephalitis (JE) is an endemic disease dominantly in the Asia-Pacific region with mortality rate varying between 3% and 30%. Long-term neuropsychiatric...
Japanese encephalitis (JE) is an endemic disease dominantly in the Asia-Pacific region with mortality rate varying between 3% and 30%. Long-term neuropsychiatric sequelae developed in 30-50% of the survivors. There is no available antiviral therapy for JE. JE vaccines play a major role in preventing this devastating disease. The incidence of JE declined over years and the age distribution shifted toward adults in countries where JE immunization program exists. Mouse brain-JE vaccine is currently replaced by inactivated Vero cell-derived vaccine and live-attenuated vaccine using SA14-14-2 strain, and live chimeric JE vaccines. These three types of JE vaccines are associated with favorable efficacy and safety profiles. Common adverse reactions include injection site reactions and fever, and severe adverse reactions are rare.
Topics: Animals; Chlorocebus aethiops; Encephalitis Virus, Japanese; Encephalitis, Japanese; Japanese Encephalitis Vaccines; Mice; Vaccines, Attenuated; Vaccines, Inactivated; Vero Cells
PubMed: 34613870
DOI: 10.1080/21645515.2021.1969852 -
F1000Research 2019Japanese encephalitis (JE) is a clinical manifestation of the brain inflammation caused by JE virus (JEV). This virus imparts permanent neurological damage, thus... (Review)
Review
Japanese encephalitis (JE) is a clinical manifestation of the brain inflammation caused by JE virus (JEV). This virus imparts permanent neurological damage, thus imposing a heavy burden on public health and society. Neuro-inflammation is the hallmark of JEV infection. The prolonged pro-inflammatory response is due primarily to microglial activation, which eventually leads to severe encephalitis. A continual effort is going on in the scientific community toward an understanding of cellular and molecular factors that are involved in JEV neuro-invasion and inflammatory processes. This review not only gives a comprehensive update on the recent advances on understanding virus structure and mechanisms of pathogenesis but also briefly discusses crucial unresolved issues. We also highlight challenging areas of research that might open new avenues for controlling virus-induced neuro-inflammation.
Topics: Encephalitis Virus, Japanese; Encephalitis, Japanese; Humans; Inflammation; Microglia
PubMed: 31781366
DOI: 10.12688/f1000research.19693.1 -
Journal of Travel Medicine May 2018Japanese encephalitis (JE) is a viral disease predominantly located in South East Asia and commonly associated with transmission between amplifying hosts, such as pigs,... (Review)
Review
BACKGROUND
Japanese encephalitis (JE) is a viral disease predominantly located in South East Asia and commonly associated with transmission between amplifying hosts, such as pigs, and the mosquito Culex tritaeniorhynchus, where human infection represents a dead end in the life cycle of the virus. The expansion of JE beyond an Asiatic confine is dependent on a multitude of complex factors that stem back to genetic subtype variation. A complex interplay of the genetic variation and vector competencies combine with variables such as geography, climate change and urbanization.
METHODS
Our understanding of JE is still at an early stage with long-term longitudinal vector surveillance necessary to better understand the dynamics of JE transmission and to characterize the role of potential secondary vectors such as Cx. pipiens and Cx. bitaeniorhynchus. The authors review the vectors indicated in transmission and the ecological, genetic and anthropological factors that affect the disease's range and epidemiology.
CONCLUSION
Monitoring for the presence of JE virus in mosquitoes in general can be used to estimate levels of potential JE exposure, intensity of viral activity and genetic variation of JEV throughout surveyed areas. Increased surveillance and diagnosis of viral encephalitis caused by genotype 5 JE virus is required in particular, with the expansion in epidemiology and disease prevalence in new geographic areas an issue of great concern. Additional studies that measure the impact of vectors (e.g. bionomics and vector competence) in the transmission of JEV and that incorporate environmental factors (e.g. weekly rainfall) are needed to define the roles of Culex species in the viral pathogenesis during outbreak and non-outbreak years.
Topics: Animals; Asia; Climate Change; Culex; Disease Outbreaks; Encephalitis Virus, Japanese; Encephalitis, Japanese; Genome; Humans; Meat-Packing Industry; Mosquito Vectors; Poultry; Prevalence; Swine
PubMed: 29718435
DOI: 10.1093/jtm/tay009 -
Viruses Feb 2023Japanese encephalitis virus (JEV) is an arboviral, encephalitogenic, zoonotic flavivirus characterized by its complex epidemiology whose transmission cycle involves...
Japanese encephalitis virus (JEV) is an arboviral, encephalitogenic, zoonotic flavivirus characterized by its complex epidemiology whose transmission cycle involves reservoir and amplifying hosts, competent vector species and optimal environmental conditions. Although typically endemic in Asia and parts of the Pacific Islands, unprecedented outbreaks in both humans and domestic pigs in southeastern Australia emphasize the virus' expanding geographical range. To estimate areas at highest risk of JEV transmission in Australia, ecological niche models of vectors and waterbirds, a sample of piggery coordinates and feral pig population density models were combined using mathematical and geospatial mapping techniques. These results highlight that both coastal and inland regions across the continent are estimated to have varying risks of enzootic and/or epidemic JEV transmission. We recommend increased surveillance of waterbirds, feral pigs and mosquito populations in areas where domestic pigs and human populations are present.
Topics: Humans; Animals; Encephalitis, Japanese; Mosquito Vectors; Encephalitis Virus, Japanese; Epidemics; Encephalitis Viruses, Japanese; Australia
PubMed: 36851664
DOI: 10.3390/v15020450 -
The Indian Journal of Medical Research 2022Japanese encephalitis (JE) is a leading cause of viral encephalitis in Southeast Asia. It is a serious public health issue in India, and cases have been emerging in... (Review)
Review
Japanese encephalitis (JE) is a leading cause of viral encephalitis in Southeast Asia. It is a serious public health issue in India, and cases have been emerging in newer areas of the country. Although vaccination efforts have already been initiated in the country since 2006 and later through the Universal Immunization Programme in 2011, still a significant reduction in the number of cases has to be achieved since an escalating trend of JE incidence has been reported in certain States such as Assam, Uttar Pradesh and West Bengal. Moreover, fresh cases of JE have been reported from certain pockets in Odisha as well. Despite the mass JE vaccination programme implemented in prioritized endemic zones in the country in 2011, a shift in the age group of JE virus (JEV) infection was noticed affecting the adult population in West Bengal. The recent detection of the circulation of genotype I (GI) in Gorakhpur, Uttar Pradesh and the co-circulation of GI and genotype III (GIII) in West Bengal are probably a warning signal for the public health personnel to strengthen the surveillance system in all endemic hotspots in the country. The abrupt emergence of JEV genotype V (GV) in China and Korea in 2009, after its first detection in Malaya in 1952, endemic countries have been cautioned to strengthen their surveillance, because GV has been suspected of getting dispersed efficiently in other parts of Asia. Moreover, the reduced protection efficiency of the JEV GIII-based vaccine against the JEV genotype V further warrants careful evaluation of the ongoing vaccination strategies in the endemic countries, anticipating the possible incursion of GV and its impact on future control strategies. In view of the above facts, the present communication reviews the current knowledge on the molecular epidemiology of JEV in India vis-a-vis the global scenario and discusses the future priorities in JEV research in India for effectively designing control strategies.
Topics: Adult; Humans; Encephalitis Virus, Japanese; Encephalitis, Japanese; India; Asia; Genotype
PubMed: 36926775
DOI: 10.4103/ijmr.IJMR_2606_19 -
Australian Journal of General Practice May 2023Japanese encephalitis virus (JEV) is a mosquito-borne arbovirus endemic to the Asia-Pacific that causes high morbidity and mortality in those who develop symptomatic... (Review)
Review
BACKGROUND
Japanese encephalitis virus (JEV) is a mosquito-borne arbovirus endemic to the Asia-Pacific that causes high morbidity and mortality in those who develop symptomatic disease. Prior to 2021, only five locally acquired cases had been detected in Australia, all in northern Australia. Following a sentinel case in 2021, widespread dissemination of JEV was detected in northern and south-eastern Australia, accompanied by an increase in locally acquired cases, which have been detected as far south as Victoria. This expansion has occurred in the setting of warmer and wetter conditions under the influence of climate change.
OBJECTIVE
To provide Australian general practitioners (GPs) an overview of JEV, given its recent expansion, and the potential for sustained endemicity.
DISCUSSION
As the distribution of JEV expands under the influence of climate change, Australian GPs need to be familiar with this condition, especially those practicing in rural areas and where detections have occurred.
Topics: Animals; Humans; Climate Change; Encephalitis Virus, Japanese; Encephalitis, Japanese; Victoria
PubMed: 37149766
DOI: 10.31128/AJGP-07-22-6484 -
Der Internist Jan 2018Mosquito-transmitted diseases represent one of the greatest health risks when traveling to tropical and sub-tropical countries. Only Japanese encephalitis and yellow...
Mosquito-transmitted diseases represent one of the greatest health risks when traveling to tropical and sub-tropical countries. Only Japanese encephalitis and yellow fever can be avoided by inoculation, and only malaria can be prevented by chemoprophylaxis. Exposure prophylaxis is the only protection against all other mosquito-born diseases. These infections need to be carefully considered in the differential diagnosis of returning travelers, taking current epidemiology into account. This review discusses common infectious diseases and the options for their diagnosis and therapy.
Topics: Animals; Chikungunya Fever; Culicidae; Dengue; Diagnosis, Differential; Encephalitis, Japanese; Germany; Health Risk Behaviors; Humans; Insect Bites and Stings; Mosquito Vectors; Travel-Related Illness; Tropical Climate; Yellow Fever; Zika Virus Infection
PubMed: 29270717
DOI: 10.1007/s00108-017-0361-6 -
Viruses Jun 2021Japanese encephalitis virus (JEV) is a zoonotic pathogen mainly found in East and Southeast Asia and transmitted by mosquitoes. The objective of this review is to... (Meta-Analysis)
Meta-Analysis Review
Japanese encephalitis virus (JEV) is a zoonotic pathogen mainly found in East and Southeast Asia and transmitted by mosquitoes. The objective of this review is to summarize the knowledge on the diversity of JEV mosquito vector species. Therefore, we systematically analyzed reports of JEV found in field-caught mosquitoes as well as experimental vector competence studies. Based on the investigated publications, we classified 14 species as confirmed vectors for JEV due to their documented experimental vector competence and evidence of JEV found in wild mosquitoes. Additionally, we identified 11 mosquito species, belonging to five genera, with an experimentally confirmed vector competence for JEV but lacking evidence on their JEV transmission capacity from field-caught mosquitoes. Our study highlights the diversity of confirmed and potential JEV vector species. We also emphasize the variety in the study design of vector competence investigations. To account for the diversity of the vector species and regional circumstances, JEV vector competence should be studied in the local context, using local mosquitoes with local virus strains under local climate conditions to achieve reliable data. In addition, harmonization of the design of vector competence experiments would lead to better comparable data, informing vector and disease control measures.
Topics: Animals; Disease Vectors; Encephalitis Virus, Japanese; Encephalitis, Japanese; Geography, Medical; Global Health; Humans; Mosquito Vectors; Population Surveillance
PubMed: 34208737
DOI: 10.3390/v13061154 -
Reviews in Medical Virology Mar 2016The mosquito-borne flavivirus, Japanese encephalitis virus (JEV), is the leading cause of virus-induced encephalitis globally and a major public health concern of... (Review)
Review
The mosquito-borne flavivirus, Japanese encephalitis virus (JEV), is the leading cause of virus-induced encephalitis globally and a major public health concern of several countries in Southeast Asia, with the potential to become a global pathogen. The virus is neurotropic, and the disease ranges from mild fever to severe hemorrhagic and encephalitic manifestations and death. The early steps of the virus life cycle, binding, and entry into the cell are crucial determinants of infection and are potential targets for the development of antiviral therapies. JEV can infect multiple cell types; however, the key receptor molecule(s) still remains elusive. JEV also has the capacity to utilize multiple endocytic pathways for entry into cells of different lineages. This review not only gives a comprehensive update on what is known about the virus attachment and receptor system (allies) and the endocytic pathways (alleys) exploited by the virus to gain entry into the cell and establish infection but also discusses crucial unresolved issues. We also highlight common themes and key differences between JEV and other flaviviruses in these contexts.
Topics: Encephalitis Virus, Japanese; Encephalitis, Japanese; Humans; Receptors, Virus; Viral Envelope Proteins; Virus Attachment; Virus Internalization; Virus Replication
PubMed: 26695690
DOI: 10.1002/rmv.1868