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PLoS Neglected Tropical Diseases Oct 2023Taiwan introduced a two-dose inactivated Japanese encephalitis (JE) mouse brain-derived (JE-MB) vaccine into routine childhood immunization in 1968, with booster...
INTRODUCTION
Taiwan introduced a two-dose inactivated Japanese encephalitis (JE) mouse brain-derived (JE-MB) vaccine into routine childhood immunization in 1968, with booster vaccination implemented in 1974 and 1983. In 2017, JE-MB vaccine was replaced by a two-dose live-attenuated chimeric vaccine (JE-CV). After implementation of JE vaccination programs, JE cases have shifted from children to adults. In this study, we described the JE epidemiology and identify high-risk groups to further inform vaccine policy.
METHODOLOGY/PRINCIPAL FINDINGS
We extracted data from Taiwan's notifiable disease surveillance database, vital statistics, and employment statistics from 2010 to 2022. Diagnosis of JE was confirmed by JE seroconversion, a four-fold increase in virus-specific antibodies, a positive JE viral nucleic-acid test, or JE virus isolation. From 2010 to 2022, a total of 313 cases of JE were diagnosed, resulting in an overall incidence rate of 0.10 cases per 100,000 person-years and a mortality rate of 0.006 per 100,000 population per year. Among these patients, 64% were male, and the median age was 51 years (range 0-82). Compared with people born in or after 1976 (vaccinated with four doses of JE-MB vaccine or two doses of JE-CV), those born in or before 1962 (unvaccinated) and those born during 1963-1975 (vaccinated with two or three doses of JE-MB vaccine) had a 4.2-fold (95% confidence interval [CI] 3.0-5.7) and 5.9-fold (95% CI 4.3-8.1) higher risk of JE, respectively. The relative risk of working in agriculture, forestry, fishing, or animal husbandry, compared to other occupations, was 5.0 (95% CI 3.5-7.0).
CONCLUSIONS/SIGNIFICANCE
In Taiwan, individuals born before 1976 and those employed in agriculture, forestry, fishing, or animal husbandry had a higher risk of JE. We recommend JE vaccination for people in these high-risk groups who have not been fully vaccinated or have an unknown vaccination history.
Topics: Child; Adult; Animals; Mice; Humans; Male; Infant, Newborn; Infant; Child, Preschool; Adolescent; Young Adult; Middle Aged; Aged; Aged, 80 and over; Female; Encephalitis, Japanese; Taiwan; Antibodies, Viral; Japanese Encephalitis Vaccines; Encephalitis Virus, Japanese; Vaccination; Vaccines, Attenuated; Risk Factors
PubMed: 37782654
DOI: 10.1371/journal.pntd.0011421 -
BMC Infectious Diseases Nov 2021Although a vaccination campaign has been conducted since 2004, Japanese encephalitis (JE) is still a public health problem in Guizhou, one of the provinces with the...
BACKGROUND
Although a vaccination campaign has been conducted since 2004, Japanese encephalitis (JE) is still a public health problem in Guizhou, one of the provinces with the highest incidence of JE in China. The aim of this study was to understand the spatiotemporal distribution of JE and its relationship with environmental factors in Guizhou Province in the post-vaccination era, 2004-2016.
METHODS
We collected data on human JE cases in Guizhou Province from 2004 to 2016 from the national infectious disease reporting system. A Poisson regression model was used to analyze the relationship between JE occurrence and environmental factors amongst counties.
RESULTS
Our results showed that the incidence and mortality of JE decreased after the initiation of vaccination. JE cases were mainly concentrated in preschool and school-age children and the number of cases in children over age 15 years was significantly decreased compared with the previous 10 years; the seasonality of JE before and after the use of vaccines was unchanged. JE incidence was positively associated with cultivated land and negatively associated with gross domestic product (GDP) per capita, vegetation coverage, and developed land. In areas with cultivated land coverage < 25%, vegetation coverage > 55%, and urban area coverage > 25%, the JE risk was lower. The highest JE incidence was among mid-level GDP areas and in moderately urbanized areas.
CONCLUSIONS
This study assessed the relationship between incidence of JE and environmental factors in Guizhou Province. Our results highlight that the highest risk of JE transmission in the post-vaccination era is in mid-level developed areas.
Topics: Adolescent; Child; Child, Preschool; China; Encephalitis, Japanese; Humans; Immunization Programs; Japanese Encephalitis Vaccines; Vaccination
PubMed: 34809606
DOI: 10.1186/s12879-021-06857-3 -
PloS One 2021Japanese encephalitis (JE) is an acute infectious disease caused by the Japanese encephalitis virus (JEV) and is transmitted by mosquitoes. Meteorological conditions are...
Japanese encephalitis (JE) is an acute infectious disease caused by the Japanese encephalitis virus (JEV) and is transmitted by mosquitoes. Meteorological conditions are known to play a pivotal role in the spread of JEV. In this study, a zero-inflated generalised additive model and a long short-term memory model were used to assess the relationship between the meteorological factors and population density of Culex tritaeniorhynchus as well as the incidence of JE and to predict the prevalence dynamics of JE, respectively. The incidence of JE in the previous month, the mean air temperature and the average of relative humidity had positive effects on the outbreak risk and intensity. Meanwhile, the density of all mosquito species in livestock sheds (DMSL) only affected the outbreak risk. Moreover, the region-specific prediction model of JE was developed in Chongqing by used the Long Short-Term Memory Neural Network. Our study contributes to a better understanding of the JE dynamics and helps the local government establish precise prevention and control measures.
Topics: Animals; Culex; Encephalitis Virus, Japanese; Encephalitis, Japanese; Humans; Humidity; Meteorological Concepts; Mosquito Vectors; Prevalence; Risk Factors; Seasons; Temperature
PubMed: 33657174
DOI: 10.1371/journal.pone.0247980 -
Journal of Medical Microbiology Dec 2022Japanese encephalitis (JE) is an infection that occurs predominantly in Asia and the Pacific Islands. It is transmitted by mosquito bites, with the main vector being...
Japanese encephalitis (JE) is an infection that occurs predominantly in Asia and the Pacific Islands. It is transmitted by mosquito bites, with the main vector being and is maintained in enzootic cycles involving pigs, wild birds and mosquitoes. JE is caused by infection with Japanese encephalitis virus (JEV), a zoonotic pathogen that also causes disease in mammals such as pigs and horses. In humans, most symptoms are mild or flu-like but can progress to encephalitis. Pigs are considered amplification hosts, and sows may have gestational complications. Horses may exhibit neurological signs. Detection of the virus can be confirmed by serological or molecular laboratory tests. Vaccination offers protection against JEV infection in humans, pigs and horses. Whilst there is no effective treatment of JE, human cases may require hospitalization for supportive therapy, which may include administration of fluids, oxygen and medication to treat symptoms.
Topics: Animals; Swine; Female; Humans; Horses; Encephalitis Virus, Japanese; Mosquito Vectors; Encephalitis, Japanese; Asia; Birds; Mammals
PubMed: 36748429
DOI: 10.1099/jmm.0.001620 -
The Lancet. Microbe Feb 2022It is unclear whether microneedle vaccinations of Japanese encephalitis virus can induce sufficient neutralising antibodies and reduce the amount of vaccine needed. We... (Randomized Controlled Trial)
Randomized Controlled Trial
Safety and dose-sparing effect of Japanese encephalitis vaccine administered by microneedle patch in uninfected, healthy adults (MNA-J): a randomised, partly blinded, active-controlled, phase 1 trial.
BACKGROUND
It is unclear whether microneedle vaccinations of Japanese encephalitis virus can induce sufficient neutralising antibodies and reduce the amount of vaccine needed. We aimed to assess the safety and dose-sparing effect of a microneedle vaccine patch against Japanese encephalitis in healthy individuals who are naive to both the vaccine and natural infection.
METHODS
The MNA-J study was a randomised, partly blinded, active-controlled, phase 1 clinical trial at Hokkaido University (Sapporo, Japan) that enrolled healthy adults aged 20-34 years with no history of Japanese encephalitis vaccination nor of infection as confirmed by seronegativity. We excluded individuals who had been infected with or vaccinated against Japanese encephalitis. Eligible participants were randomly assigned (1:1:1) to one of three groups to receive inactivated Japanese encephalitis vaccine administered twice, 3 weeks apart, by either 2·5 μg per injection by subcutaneous injection, 0·63 μg per patch by high-dose microneedle array (MNA-25%), or 0·25 μg per patch by low-dose microneedle array (MNA-10%). The randomisation sequence, using stratification by cohort and blocks of six, was computer-generated by a statistician who was unaware of group assignment. After administration, the remaining amount of unadministered vaccine was measured by ELISA and calculated as the delivered amount of vaccine. The primary outcome was the neutralising antibody titre at day 42 after first immunisation. Successful seroconversion was defined as post-vaccination titres of 1·3 (log) or higher in individuals whose pre-vaccination titres had been less than 1 (log). This study is registered with the Japan Registry of Clinical Trials (s011190004).
FINDINGS
Between Aug 31 and Sept 2, 2019, 39 participants were enrolled and each was randomly assigned to a group (n=13 per group). No serious adverse events were observed. All participants in the microneedle array groups had a localised erythematous reaction. The amount of vaccine delivered by microneedle array to each participant was 0·63-1·15 μg (50-92%) of the full 1·26 μg for the MNA-25% group and 0·25-0·41 μg (51-84%) of the full 0·50 μg for the MNA-10% group. All participants demonstrated seroconversion at day 42, and the mean titres (log) were 2·55 for MNA-25%, 2·04 for MNA-10%, and 2·08 for subcutaneous injection.
INTERPRETATION
A microneedle patch of the Japanese encephalitis vaccine is safe, well tolerated, and immunogenically effective. The dose-sparing effect suggests a significant potential to reduce the amount of immunogens needed. However, improved delivery is needed to make it more tolerable and user friendly.
FUNDING
FUJIFILM.
Topics: Adult; Antibodies, Viral; COVID-19; COVID-19 Vaccines; Encephalitis, Japanese; Humans; Immunogenicity, Vaccine; Japanese Encephalitis Vaccines; SARS-CoV-2; Vaccines, Inactivated
PubMed: 35544051
DOI: 10.1016/S2666-5247(21)00269-X -
Journal of Microbiology and... Sep 2022Japanese encephalitis virus (JEV), the causative agent of Japanese encephalitis (JE), is an importantly zoonotic, vector-borne virus widely prevalent in Asia. Although...
Japanese encephalitis virus (JEV), the causative agent of Japanese encephalitis (JE), is an importantly zoonotic, vector-borne virus widely prevalent in Asia. Although JE has been well controlled in China, its prevalence remains a huge threat to the pig industry as well as human health. Herein, we report on our molecular and serological investigations of JEV among pigs from different regions in Hunan Province of China from 2019 to 2021. Collectively, 19.27% (583/3026, 95% Confidential Interval (CI) 17.86-20.68) of sampled pigs were positive for JEV IgG antibody as revealed by indirect enzyme-linked immunosorbent assay, and the seroprevalence of JEV among pigs was significantly associated with the development stage and breeding scale ( < 0.01). Meanwhile, 10.99% (42/382, 95% CI 7.86-14.13) of tissue samples of pigs with suspected clinical symptoms of JE and 23.44% (15/64, 95% CI 13.06-33.82) of mosquito batches were JEV-positive via reverse polymerase chain reaction. In addition, the complete E gene sequences of 14 JEV strains identified in this study were amplified and sequenced. Phylogenetic analysis showed that all 14 JEV strains belonged to genotype I-b and displayed a distinct genetic relationship to the present JEV vaccine strain (SA14-14-2). In conclusion, our results revealed not only the severe prevalence of JEV in Hunan Province, but also that JEV I-b might be the predominant genotype in Hunan Province, suggesting therefore that effective measures for JE control are urgently needed.
Topics: Animals; Antibodies, Viral; China; Culicidae; Encephalitis Virus, Japanese; Encephalitis, Japanese; Genotype; Humans; Immunoglobulin G; Mosquito Vectors; Phylogeny; Prevalence; Seroepidemiologic Studies; Swine
PubMed: 36116917
DOI: 10.4014/jmb.2207.07068 -
Viruses Nov 2022Japanese encephalitis virus (JEV) is an important arbovirus in Asia that can cause serious neurological disease. JEV is transmitted by mosquitoes in an enzootic cycle...
Japanese encephalitis virus (JEV) is an important arbovirus in Asia that can cause serious neurological disease. JEV is transmitted by mosquitoes in an enzootic cycle involving porcine and avian reservoirs, in which humans are accidental, dead-end hosts. JEV is currently not endemic in Singapore, after pig farming was abolished in 1992; the last known human case was reported in 2005. However, due to its location along the East-Asian Australasian Flyway (EAAF), Singapore is vulnerable to JEV re-introduction from the endemic regions. Serological and genetic evidence in the last decade suggests JEV's presence in the local fauna. In the present study, we report the genetic characterization and the first isolation of JEV from 3214 mosquito pools consisting of 41,843 mosquitoes, which were trapped from April 2014 to May 2021. The findings demonstrated the presence of genotype I of JEV (n = 10), in contrast to the previous reports of the presence of genotype II of JEV in Singapore. The genetic analyses also suggested that JEV has entered Singapore on several occasions and has potentially established an enzootic cycle in the local fauna. These observations have important implications in the risk assessment and the control of Japanese encephalitis in non-endemic countries, such as Singapore, that are at risk for JEV transmission.
Topics: Swine; Animals; Humans; Encephalitis Virus, Japanese; Singapore; Encephalitis, Japanese; Culicidae; Culex; Genotype
PubMed: 36560666
DOI: 10.3390/v14122662 -
Journal of Vector Borne Diseases 2021Japanese encephalitis (JE) is a major public health problem in many states of India. Uttar Pradesh state contributes 75% of the total cases reported. A longitudinal...
BACKGROUND & OBJECTIVES
Japanese encephalitis (JE) is a major public health problem in many states of India. Uttar Pradesh state contributes 75% of the total cases reported. A longitudinal study was undertaken to find out the seasonal abundance, infection in the JE vectors in Gorakhpur region of Uttar Pradesh, and intervention strategies like indoor residual spraying and long-lasting insecticidal nets were adopted.
METHODS
The vector abundance was monitored from July 2013 to August 2016 at fortnightly intervals and identified using standard mosquito identification keys and screened for viral infection. Intervention measures like indoor residual spraying with lambda-cyhalothrin 10% WP at 25 mg/m in 58 gramasabha in Bhathat Block and long-lasting insecticidal nets were distributed @ 2 LLIN for each household with 5-6 members in 5 villages of Korabar block.
RESULTS
A total of 5,36,609 mosquitoes constituting 34 species and 10 genera were collected during this study period. Among the JE vector, peak abundance of Culex tritaeniorhynchus was recorded just before the JE season from July to October in all the blocks. There was a marked reduction in the density of Cx. tritaeniorhynchus from July compared to baseline year 2014 in Bhathat Block where indoor residual spraying (IRS) was performed in June 2015. The vector density declined in 5 villages of Khorabar Block where long-lasting impregnated bed nets (LLINs) were distributed during July 2016.
INTERPRETATION & CONCLUSION
The present study provided knowledge about the seasonal JE vector density and JE virus infection in mosquitoes during the monsoon season in Gorakhpur region of Uttar Pradesh. IRS and the personal protection measure like LLINs were distributed to interrupt the JE transmission in this area which gave encouraging results.
Topics: Animals; Culex; Encephalitis Virus, Japanese; Encephalitis, Japanese; India; Longitudinal Studies; Mosquito Vectors; Seasons
PubMed: 35170465
DOI: 10.4103/0972-9062.321740 -
Journal of Medical Microbiology Mar 2023
Topics: Humans; Encephalitis, Japanese; India; Genotype
PubMed: 36943342
DOI: 10.1099/jmm.0.001677 -
Infection Dec 2022Japanese encephalitis is an arthropod-borne zoonotic flavivirus infection endemic to tropical and subtropical Asia. A minority of infections leads to a symptomatic... (Review)
Review
BACKGROUND
Japanese encephalitis is an arthropod-borne zoonotic flavivirus infection endemic to tropical and subtropical Asia. A minority of infections leads to a symptomatic course, but affected patients often develop life-threatening encephalitis with severe sequelae.
LITERATURE REVIEW
Myelitis with flaccid paralysis is a rare complication of Japanese Encephalitis, which-according to our literature search-was reported in 27 cases, some of which were published as case reports and others as case series. Overall, there is a broad clinical spectrum with typically asymmetric manifestation and partly severe motor sequelae and partly mild courses. Lower limb paralysis appears to be more frequent than upper limb paralysis. An encephalitic component is not apparent in all cases CASE PRESENTATION: We herein add the case of a 29 year-old female who developed encephalitis and myelitis with flaccid paralysis during a long-time stay in Indonesia. Diagnostic workup in Indonesia did not clearly reveal an underlying cause. Upon clinical stabilization, the patient was evacuated to her home country Germany, where further diagnostics confirmed Japanese encephalitis virus as the causative agent. The patient has partly recovered, but still suffers from residual paralysis of the upper limb.
CONCLUSION
Flaccid paralysis is a rare, and likely underdiagnosed complication of Japanese encephalitis, which, to the best of our knowledge, has never been diagnosed outside endemic areas before.
Topics: Humans; Female; Adult; Encephalitis, Japanese; Myelitis; Paralysis; Lower Extremity; Germany
PubMed: 35396695
DOI: 10.1007/s15010-022-01815-w