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

Abstract

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.

A Retrospective Study of the Clinical Characteristics of Japanese Encephalitis in Adults

“…However, most adults in China are not vaccinated against the disease, and the incidence of adult morbidity is still relatively high through the transmission of the viruscarrying. One study showed that the number of patients over the age of 15 with JE has been increasing in the past few years, accounting for 82.48% of the total number of patients in 2016, and the proportion of middle-aged and elderly people suffering from JE is also increasing, rising from 2.93% in 2011 to 21.82% in 2016 [5]. However, geriatric patients are not given enough attention because this age group is not listed as an at-risk population [6].…”

Cognitive decline following acute viral infections: literature review and projections for post-COVID-19

“…Japanese encephalitis (JE) is the most common cause of encephalitis in Asia, affecting mainly children. Adult cases are increasingly reported [ 66 ]. JE is also a relevant cause of encephalitis in the western pacific, and JE cases have also been reported in Australia [ 67 ].…”

“…Around 45–64% of survivors show neurological sequelae on hospital discharge [ 72 – 74 ]. In a Chinese retrospective series of 50 JE patients [ 66 ], 12% died during hospital admission, 75% had significant functional limitations upon discharge, and 39% of survivors had major limitations after 18 months.…”

Safety of Japanese encephalitis vaccines

“…However, the age distribution shifted toward adults currently in countries where JE immunization program exists. 7,[9][10][11][12] Due to the introduction of JE vaccine, urbanization and improved sanitary and public health measures, the incidence of JE decreased year by year in many endemic countries. The estimated incidence of JE in Korea was 0.1-1.8 per 1,00,000 population during 1980-1984 and decreased to 0.013-0.055 per 1,00,000 population during 2007-2010.…”

“… 4 , 6 Several reports show that JE in young children and the elderly were more likely to be associated with severe sequelae and a higher mortality rate than young adults. 6 , 7 …”