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Vaccine Mar 2020Japanese encephalitis (JE) is endemic in the Western Pacific Region. We aim to describe the regional status of control of JE, based on the World Health Organization...
Japanese encephalitis (JE) is endemic in the Western Pacific Region. We aim to describe the regional status of control of JE, based on the World Health Organization (WHO) surveillance data, and to share the experience from the Republic of Korea. Substantial progress has been made in the region to date; however, epidemiologic changes have not been delineated. The vaccination coverage should be addressed to close the immunity gap. The lessons learned from Korea may aid in establishing a high-quality surveillance system with a sustainable JE vaccination program in order to prepare for new challenges that this region will face.
Topics: Encephalitis Virus, Japanese; Encephalitis, Japanese; Epidemiological Monitoring; Humans; Japanese Encephalitis Vaccines; Republic of Korea; World Health Organization
PubMed: 32111531
DOI: 10.1016/j.vaccine.2020.02.061 -
Clinical Infectious Diseases : An... Jul 2002The prevention of Japanese encephalitis in travelers presents the juxtaposition of 4 factors: a disease that is widespread throughout Asia, a disease with a low... (Review)
Review
The prevention of Japanese encephalitis in travelers presents the juxtaposition of 4 factors: a disease that is widespread throughout Asia, a disease with a low incidence in travelers, a vaccine about which there are safety concerns, and a clinical course that can result in death or permanent disability in two-thirds of symptomatic cases. Travel medicine practitioners often seem to be polarized into 2 groups: a group that gives more weight to the severity of the disease (and therefore often recommend vaccination) and another group that is more persuaded by the low occurrence of cases in travelers (and therefore rarely recommend vaccination). This review assesses the known risks of contracting Japanese encephalitis and the risks associated with the vaccine and tries to develop an appropriate way to recommend this vaccine to travelers who may be at significant risk.
Topics: Asia; Encephalitis Virus, Japanese; Encephalitis, Japanese; Humans; Japanese Encephalitis Vaccines; Risk Factors; Travel
PubMed: 12087525
DOI: 10.1086/341247 -
Viruses Aug 2022The detection of a new and unexpected Japanese encephalitis virus (JEV) outbreak in March 2022 in Australia, where JEV is not endemic, demanded the rapid development of...
The detection of a new and unexpected Japanese encephalitis virus (JEV) outbreak in March 2022 in Australia, where JEV is not endemic, demanded the rapid development of a robust diagnostic framework to facilitate the testing of suspected patients across the state of New South Wales (NSW). This nascent but comprehensive JEV diagnostic service encompassed serological, molecular and metagenomics testing within a centralised reference laboratory. Over the first three months of the outbreak (4 March 2022 to 31 May 2022), 1,061 prospective samples were received from 878 NSW residents for JEV testing. Twelve confirmed cases of Japanese encephalitis (JE) were identified, including ten cases diagnosed by serology alone, one case by metagenomic next generation sequencing and real-time polymerase chain reaction (RT-PCR) of brain tissue and serology, and one case by RT-PCR of cerebrospinal fluid, providing an incidence of JE over this period of 0.15/100,000 persons in NSW. As encephalitis manifests in <1% of cases of JEV infection, the population-wide prevalence of JEV infection is likely to be substantially higher. Close collaboration with referring laboratories and clinicians was pivotal to establishing successful JEV case ascertainment for this new outbreak. Sustained and coordinated animal, human and environmental surveillance within a OneHealth framework is critical to monitor the evolution of the current outbreak, understand its origins and optimise preparedness for future JEV and arbovirus outbreaks.
Topics: Animals; Australia; Disease Outbreaks; Encephalitis Virus, Japanese; Encephalitis, Japanese; Genotype; Humans; New South Wales; Prospective Studies
PubMed: 36146660
DOI: 10.3390/v14091853 -
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 -
PLoS Neglected Tropical Diseases Jul 2022Japanese encephalitis (JE) is a vector-borne zoonosis and the leading cause of human viral encephalitis in Asia. Its transmission cycle is usually described as involving...
Japanese encephalitis (JE) is a vector-borne zoonosis and the leading cause of human viral encephalitis in Asia. Its transmission cycle is usually described as involving wild birds as reservoirs and pigs as amplifying hosts. JE is endemic in Cambodia, where it circulates in areas with low pig densities (<70 pigs per km2), and could be maintained in a multi-host system composed of pigs, but also poultry as competent hosts, and dogs, cattle and humans as non-competent hosts. We used a mathematical model representing Japanese encephalitis virus (JEV) transmission in a traditional Cambodian village that we calibrated with field data collected in 3 districts of Kandal province, Cambodia. First, R0 calculations allowed us to assess the capacity of the epidemiological system to be invaded by JEV and sustain virus transmission in villages in the 3 districts, and we predicted human exposure at the epidemiological equilibrium, based on simulations. Changes in spatial density of livestock, in agricultural practices, and epizootics (e.g., African swine fever), can profoundly alter the composition of host communities, which could affect JEV transmission and its impact on human health. In a second step, we then used the model to analyse how host community composition affected R0 and the predicted human exposure. Lastly, we evaluated the potential use of dog JE seroprevalence as an indicator of human exposure to JEV. In the modeled villages, the calculated R0 ranged from 1.07 to 1.38. Once the equilibrium reached, predicted annual probability of human exposure ranged from 9% to 47%, and predicted average age at infection was low, between 2 and 11 years old, highlighting the risk of severe forms of JEV infection and the need to intensify child immunization. According to the model, increasing the proportion of competent hosts induced a decrease in age at infection. The simulations also showed that JEV could invade a multi-host system with no pigs, reinforcing the assumption of poultry acting as reservoirs. Finally, the annual human exposure probability appeared linearly correlated with dog seroprevalence, suggesting that in our specific study area, dog seroprevalence would be a good proxy for human exposure.
Topics: African Swine Fever; Animals; Asian People; Cattle; Child; Child, Preschool; Dogs; Encephalitis Virus, Japanese; Encephalitis, Japanese; Humans; Seroepidemiologic Studies; Swine
PubMed: 35816555
DOI: 10.1371/journal.pntd.0010572 -
Journal of Travel Medicine 2009
Review
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Asia, Southeastern; Child; Encephalitis, Japanese; Europe; Female; Humans; Japanese Encephalitis Vaccines; Male; Middle Aged; Risk Factors; Seasons; Travel; Young Adult
PubMed: 19538584
DOI: 10.1111/j.1708-8305.2009.00333.x -
Indian Journal of Pediatrics 1997Japanese encephalitis (JE), caused by a mosquito-borne virus was first recognised in India in 1955 and since then many major out-breaks from different parts of the...
Japanese encephalitis (JE), caused by a mosquito-borne virus was first recognised in India in 1955 and since then many major out-breaks from different parts of the country have been reported, predominantly in rural areas. Children are mainly affected, with morbidity rate estimated at 0.30 to 1.5 per 100,000 population. Case fatality rate has ranged from 10% to 60%, and up to 50% of those who recover may be left with neurological deficits. Reported incidence has generally been higher in males than in females, but subclinical infections have occurred equally in both sexes. A large number of subclinical infections occur each year during the transmission season. Diagnosis at the primary health centre (PHC) level is based on clinical symptoms only. Therefore, there is a need to develop simple tests for use at the peripheral level both for diagnosis and for epidemiological surveys. JE is a vaccine preventable disease, but there are many logistic problems for effective implementation of vaccination.
Topics: Adolescent; Child; Child, Preschool; Cross-Sectional Studies; Developing Countries; Encephalitis, Japanese; Female; Humans; Incidence; India; Infant; Male
PubMed: 10771844
DOI: 10.1007/BF02752458 -
Expert Opinion on Therapeutic Targets 2015Japanese 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... (Review)
Review
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.
Topics: Animals; Antiviral Agents; Drug Delivery Systems; Drug Design; Encephalitis Virus, Japanese; Encephalitis, Japanese; Humans; Japanese Encephalitis Vaccines; Virus Replication
PubMed: 26156208
DOI: 10.1517/14728222.2015.1065817 -
Neurology Nov 2018
Topics: Antibodies, Viral; Encephalitis, Japanese; Female; Humans; Young Adult
PubMed: 30455264
DOI: 10.1212/WNL.0000000000006553 -
Nihon Rinsho. Japanese Journal of... Mar 2007