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

Abstract

Japanese encephalitis (JE) virus is a major cause of devastating viral encephalitis, especially in Asia. Although a successful vaccination program led to its near-elimination over three decades in South Korea, the incidence of JE has increased since 2010. The present study investigated the clinical manifestations, laboratory findings, and factors affecting neurological outcomes of reemerging JE. We retrospectively reviewed medical records of laboratory-confirmed JE patients who presented with acute encephalitis syndrome at three tertiary hospitals between 2010 and 2015. A total of 17 patients with JE were identified. Their median age was 51 years, and 10 (58.5%) were men. The most common symptoms and signs were fever (94.1%), altered consciousness (94.1%), and headache (80.2%). Hyporeflexia (47.1%), seizures (35.2%), abnormal brainstem reflex (23.5%), and flaccid weakness (17.6%) were also noted. Brain imaging revealed thalamic lesions in all patients, with the hippocampus, midbrain, basal ganglia, and cerebral cortex affected to varying degrees. Sixteen patients (94.1%) required management in the intensive care unit with mechanical ventilation due to neurological deterioration. At the time of discharge, 11 (64.7%) had poor recovery, defined as Glasgow coma scale scores of less than 8, and remained ventilator dependent. Comparison between the two outcome groups indicated that midbrain involvement ( = 0.028) and rapid deterioration ( = 0.005) were associated with severe neurological sequelae. Given that JE is a vaccine-preventable disease, vaccination for adults should be considered in response to the reemergence of JE.

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

“…No remarkable findings were found in the neuroimaging, except for the concurrent presence of white matter hyperintensities, which might be related to the pathomechanisms and vascular risk factors in elderly individuals, yet it was unknown whether it was irrelevant change before the acute onset of encephalitis. Regarding the neuroimaging findings of JE, thalamic lesions were noted in most patients in our study, and extrathalamic lesions such as lesions in the basal ganglia were also common; this was in accordance with previous studies (10). The most prominent problems during the course of the disease were not seizures or paralysis, but rather, secondary respiratory failure and other critical secondary complications which needed intensive care support.…”

“…One retrospective study from South Korea identified 17 cases in three tertiary hospitals from 2010 to 2015; of these, 11 patients were bedridden at discharge, and 10 of the 17 patients were over 50 years old. Though the age of the patients did not have a significant association with whether the patients were bedridden or not, this result is explainable due to the small sample size of the study (10). Some studies have indicated that the mortality rate was higher as the age increased, with one study from China reporting a rate of 14.67% in patients over 70 years; this rate was relatively lower compared to that in our study, which might be due to the different study designs (14).…”

“…To the best of our knowledge, this is the first report to evaluate elderly patients with JE from an adult tertiary hospital in West China. Previous studies of mortality due to JE in adults reported varied rates, from 0 to 43%, with very few studies assessing the mortality in patients aged over 50 years (10–12). Studies that compared the demographics and clinical features between those with poor outcomes and better outcomes were unable to list age at onset as a risk factor, since these studies were performed in pediatric patients (2, 13).…”

Systematic review of seroepidemiological studies on Japanese encephalitis in the Republic of Korea

“…Despite these limitations, the data compiled highlight consistent changes in JEV susceptibility and may aid in the identification of vulnerable populations in Korea. This study indicates that protective immunity remains high in adults vaccinated during childhood, up until the age of at least 30 years (Sunwoo et al, 2017). This may be a reflection of the duration of protection of the vaccines, or a consequence of natural boosting in these vaccinated individuals.…”

The first documented case of Japanese encephalitis imported to the Czech Republic

“…Rostoucí ri ziko je patrné i u japonské encefalitidy (JE), dříve v diferenciální dia gnostice opomíjené neuroinfekce [1]. Jedná se o nejčastější viro vou encefalitidu vyskytující se v zemích ji hovýchodní Asie a západního Pacifiku [2]. Původcem onemocnění je RNA virus z če ledi Flaviviridae.…”