Clinical Characteristics of Severe Japanese Encephalitis: A Case Series from South Korea

Japanese Encephalitis Outbreak in Young Adults of Bastar District in Chhattisgarh: A Short Observational Study

Background Instant infections in children due to acute encephalitis syndrome (AES) were reported in a tribal district of Bastar in Chattisgarh, India, between August 2018 and August 2019. Objective The study was conducted to explore the possibility of a viral cause indicating an outbreak. Methods Clinical surveys and serological investigation tests were conducted to identify the viral etiology. The Bastar area in Chhattisgarh reported factors such as paddy fields near homes, a high pig-to-cattle ratio, a significant presence of Culex vishnui mosquitoes, low socioeconomic status, and a lack of health awareness among the tribal people. Result This study, conducted at the Late Baliram Kashyap Memorial Government Medical College in Jagdalpur, Bastar, Chhattisgarh, India, analyzed 128 samples from fever cases out of 213 patients visiting the Japanese encephalitis virus (JEV) testing center. Among these samples, 71 cases exhibited AES, and subsequent JEV IgM ELISA testing identified 18 cases as JEV-positive, signifying recent JEV infections. Notably, the overwhelming majority (94.44%) of JEV-positive patients were under 16 years old, highlighting the heightened vulnerability of children to JEV illness in the Bastar region. Although male patients accounted for 61.11% of the JEV-positive cases compared to 38.88% of female patients, statistical analysis revealed that this gender disparity was not statistically significant (p-value = 0.18). Conclusion The study emphasizes the significance of identifying the etiology and delivering evidence-based care to patients with AES. Improved diagnosis and management of AES may result from a greater comprehension of the advantages and disadvantages associated with the application and administration of common laboratory and diagnostic algorithms.

The spatiotemporal distribution and prognostic factors of Japanese encephalitis in Shanxi Province, China, 2005-2022

Japanese encephalitis (JE) is a naturally occurring localized disease caused by the Japanese encephalitis virus, which is spread by the Culex tritaeniorhynchus. China has a high rate of JE. Shanxi, located in North China, has a high prevalence of adult JE. Adult JE has more severe complications, mortality, and a higher disease burden, making it a public health issue. This retrospective study examined the dynamic epidemic changes, high-risk areas of JE, and clinical characteristics and prognostic factors of adult JE in Shanxi Province. The findings revealed that July to September was the primary epidemic season of JE and that JE cases were mainly in individuals over the age of 40. The incidence of JE from 2005 to 2022 demonstrated a positive spatial correlation with significant clustering characteristics, with high-incidence clusters in the south and southeast. Multivariate logistic regression analysis revealed that higher cerebrospinal fluid pressure, higher white blood cell counts, higher neutrophil percentage, deep coma, and lower albumin were independent factors for poor prognosis of adult JE. The developed risk prediction model holds great promise in early prognosis assessment of patients, providing a basis for clinical decision-making and early clinical intervention.

Human microglial models to study host-virus interactions

Microglia, the resident macrophage of the central nervous system, are increasingly recognized as contributing to diverse aspects of human development, health, and disease. In recent years, numerous studies in both mouse and human models have identified microglia as a "double edged sword" in the progression of neurotropic viral infections: protecting against viral replication and cell death in some contexts, while acting as viral reservoirs and promoting excess cellular stress and cytotoxicity in others. It is imperative to understand the diversity of human microglial responses in order to therapeutically modulate them; however, modeling human microglia has been historically challenging due to significant interspecies differences in innate immunity and rapid transformation upon in vitro culture. In this review, we discuss the contribution of microglia to the neuropathogenesis of key neurotropic viral infections: human immunodeficiency virus 1 (HIV-1), Zika virus (ZIKV), Japanese encephalitis virus (JEV), West Nile virus (WNV), Herpes simplex virus (HSV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We pay special attention to recent work with human stem cell-derived microglia and propose strategies to leverage these powerful models to further uncover species- and disease-specific microglial responses and novel therapeutic interventions for neurotropic viral infections.

Who Is at Risk? A Critical Case of Japanese Encephalitis

Japanese encephalitis (JE) is critical epidemic encephalitis caused by the JE virus (JEV) in Southeast Asia. The World Health Organization defined "acute encephalitis syndrome" (AES) as an acute onset of fever with a change of mental status and/or new-onset seizure, mainly for the surveillance of JE. The key clues for the diagnosis include the patient age group of unvaccinated era or waning vaccine-induced immunity and the history of possible mosquito bites in epidemic areas. We report a 47-year old man who is in an unvaccinated era with potential waning immunity. The patient presented with fever and altered mental status for 2 days. He was speechless and could not follow commands. The patient had gone camping in the countryside a week before the visit. At the emergency department, neck stiffness was noted. There was a leukocytosis with a left shift by blood cell count. The brain computed tomography was essentially normal. The cerebrospinal fluid (CSF) sample via lumbar puncture showed leukocytosis, a high protein level, and a low sugar level in comparison to serum tests. Further antibody test of CSF confirmed the diagnosis. Magnetic resonance imaging (MRI) of the brain revealed a high signal in the right thalamus and a mildly swollen left caudate nucleus 4 days after admission. He was extubated and finally discharged with partial dependency on activities of daily living. This case reminds us of the JE in AES. Emergency physicians should be aware of the suspicious case of unvaccinated age or waning immunity and possible mosquito bites in epidemic areas. The role of MRI on JE was also discussed in this article.

Estimates of Japanese Encephalitis mortality and morbidity: A systematic review and modeling analysis

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.

Japanese Encephalitis (JE) is known for its high case fatality ratio (CFR) and long-term neurological sequelae. Although JE fatality and morbidity risk might change as the characteristics of the population change with the strengthened surveillance scales, expanded immunization coverage, and healthcare improvements, there have not been any updates in the estimates for JE mortality and morbidity estimates for 10 years. In this paper, we made updated estimates of the JE CFR and the proportion of JE survivors with long-term neurological sequelae by performing a systematic review and developing statistical and machine learning models. We estimated JE CFR decreased over time, with 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. countries without JE vaccination, younger JE cases, higher population growth rate, and lower rural population percentage were associated with higher JE CFR. 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%) JE patients still had neurological sequelae. The insights gained will be important in evaluating and updating current JE disease burden among all endemic areas and effectively channeling resources to most needed areas.

Myelitis with flaccid paralysis due to Japanese encephalitis: case report and review of the literature

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.

Long-term neurological and healthcare burden of adults with Japanese encephalitis: A nationwide study 2000-2015

Objective

To assess the healthcare utilization, economic burden, and long-term neurological complications and mortality of an adult population with Japanese encephalitis (JE).

Methods

This study utilized two nationwide datasets in Taiwan: the Notifiable Disease Dataset of confirmed cases from the Centers for Disease Control to identify JE patients, and the National Health Insurance Research Database to obtain patients’ healthcare utilization. Survival analyses were performed to identify prognostic factors associated with the all-cause mortality of patients.

Results

This study included 352 adult cases with JE (aged≥20 years). The mean age of JE patients was 45 years. Stroke (event rate: 3.49/100 person-years) was the most common neurological complication, followed by epilepsy/convulsions (3.13/100 person-years), encephalopathy/delirium (2.20/100 person-years), and parkinsonism (1.97/100 person-years). Among the 336 hospitalized patients at JE diagnosis, 58.33% required intensive care. Among 79 patients who died following JE diagnosis, 48.84% of death events occurred within the year of diagnosis. The medical costs increased considerably at JE diagnosis and subsequent-year costs remained significantly higher than the costs before diagnosis (p<0.05). Having a four-dose JE vaccination (i.e., born after 1976) versus no JE vaccination history (i.e., born before 1963) was significantly associated with lower all-cause mortality (hazard ratio: 0.221 [95% confidence interval: 0.067, 0.725]). Comorbid diabetes and incident epilepsy/convulsion events significantly increased the mortality risk by 2.47- and 1.85-fold, respectively (p<0.05).

Conclusion

A considerable medical burden associated with JE was observed in affected adults, even in the years following JE diagnosis. Vaccination should be considered to prevent this sporadic, but lethal, viral infection.

The epidemiology of adulthood Japanese encephalitis (JE) remains limited, and data on the economic burden associated with JE is lacking. This study is the first to comprehensively examine the healthcare burden (i.e., healthcare utilization and costs, neurological complications, all-cause mortality) of an adult population with JE, utilizing a nationwide cohort of JE-infected adults with up to 16 years of follow-up. In the first 6 months following JE diagnosis, a higher rate of neurological disorders was found, compared to the years after the diagnosis, with stroke being the most common neurological complication, followed by epilepsy/convulsions. The healthcare utilization of JE patients was higher in the first 6 months after the diagnosis compared to the years following the diagnosis. Medical costs increased considerably at JE diagnosis and subsequent-year costs after diagnosis remained higher than the cost before diagnosis. Having comorbid diabetes or incident epilepsy/convulsion events was a significant risk factor for mortality of adults with JE. Being born after 1976 in Taiwan, and thus likely receiving a four-dose schedule of vaccination, was associated with reduced mortality. Therefore, special attention is required for JE patients with comorbid diabetes or incident epilepsy/convulsion events, and JE vaccination should be considered to prevent this sporadic but lethal viral infection.

Determining the clinical characteristics and prognostic factors for the outcomes of Japanese encephalitis in adults: A multicenter study from southern Taiwan

BACKGROUND

In Southeast Asia, Japanese encephalitis (JE) is an important cause of viral encephalitis which may cause severe neurological sequelae. JE affects mostly children; therefore, clinical presentations and prognosis of adult JE patients are seldom addressed. This study aimed to describe the clinical characteristics and prognostic factors for the outcome of adult JE patients.

METHODS

Medical records of adult JE patients with acute encephalitis syndrome during 2001-2018 from five medical centers in southern Taiwan were reviewed. Clinical characteristics, brain images, and prognostic factors for outcomes were analyzed. Patients were divided into the good outcome (GO) group and poor outcome (PO) group according to their Glasgow Coma Scale (GCS) scores (GCS >8 vs. ≤ 8) at discharge.

RESULTS

Sixty-eight patients (men, 61.8%; median age, 50 years) were included. Summer is the epidemic season, and the number of cases peaked in June. The most common symptoms at initial presentation were altered consciousness and fever (both 94.1%), followed by headache (51.4%). The most commonly involved brain regions were thalamus (55.7%) and basal ganglion (37.7%). The median GCS score at nadir was 8, and the median time from onset to nadir was five days. Fifty-two patients were included in the GO group, while 16 were included in the PO group. On multivariate analysis, flaccidity, rigidity, and elevated CSF protein level were identified as independent prognostic factors for PO.

CONCLUSION

Initial clinical presentations of abnormal muscle tone including flaccidity, rigidity and high CSF protein levels are independent prognostic factors for PO in adult JE patients.

Mortality and Disability Due to Japanese Encephalitis in Elderly Adults: Evidence From an Adult Tertiary Care Center in West China

Japanese encephalitis (JE) is the most important cause of viral encephalitis in Asia, with most cases seen in children <15 years. Recently, cases of JE in people aged >50 years have been increasingly reported, but the clinical presentation in these cases is largely unknown. We report here the first case series of elderly JE patients from an adult tertiary hospital in West China. Medical records of laboratory-confirmed JE patients diagnosed from January 2011 to September 2018 were reviewed retrospectively. Patients were grouped into the elderly (patients > 50 years old) and control groups (patients aged 14-50 years). Data regarding demographics, clinical features, and outcome at discharge were collected. Telephonic follow-up was performed with the survivors in November 2018. Of the 50 patients with laboratory-confirmed JE, 11 were aged >50 years. In the elderly group, all patients had high fever and altered sensorium, and six had symptomatic seizures. Though the key symptoms as well as the cerebrospinal fluid and neuroimaging findings were similar in both groups, the worst Glasgow coma scale score was lower in the elderly group (6.14 ± 2.27 vs. 10.54 ± 3.37, p = 0.001). Compared to the control group, the incidence of acute secondary complications, including respiratory failure requiring mechanical ventilation or tracheotomy (81.82%), hypoalbuminemia (100%), thrombocytopenia (100%), deep venous thrombosis (63.64%), septicemia (36.36%), and upper gastrointestinal bleeding (27.27%) was higher in the elderly. The median modified Rankin scale (mRS) score at discharge was lower in the elderly group than in the control group (5 vs. 3, p = 0.017), with four and two cases of death, respectively. During the average 18-month follow-up, the median mRS score was 5 in the elderly and 2 in the control group (p = 0.001). Patients >50 years old accounted for 22% of JE cases diagnosed in a tertiary adult center, with high mortality rate and long-term disability compared to younger patients. Though no particular findings were found regarding clinical features and investigations in patients >50 years, most needed intensive care. In the future, it is imperative to recognize the importance of JE in adults and to reconsider the vaccination strategy in adult residents of endemic areas, especially for those over 50 years.

Trismus caused by paraneoplastic brainstem encephalitis

We discuss the assessment and differential diagnoses of a middle-aged man who presented with trismus, double vision and behavioural problems. MRI scan of the brain was initially normal, but a month later showed high signal in the hippocampal region on fluid attenuated inversion recovery sequence (FLAIR) imaging. We suspected a paraneoplastic brainstem encephalitis because of his smoking history, rapidly progressive symptoms and abnormal brainstem signs. A positron emission tomography-CT scan identified abnormal subcarinal nodes, shown on biopsy to be metastatic small cell lung cancer. He is currently undergoing treatment with chemotherapy and radiotherapy.