Burden of Encephalitis in Low- and Middle-Income Countries, 1990-2023

Encephalitis remains a major cause of neurological morbidity and mortality worldwide, particularly in resource-limited settings. This study analyzed the long-term trends and disparities in encephalitis burden across 131 low- and middle-income countries (LMICs) from 1990 to 2023.

Data were obtained from the Global Burden of Disease 2023 study for 131 LMICs. Incidence, prevalence, deaths, and disability-adjusted life years (DALYs) were analysed using absolute counts and age-standardised rates. Trends were assessed with estimated annual percentage changes, joinpoint regression, age-period-cohort analysis, correlations with socio-demographic index (SDI), and decomposition analysis.

In 2023, encephalitis in LMICs caused 1.59 million incident cases, 5.21 million prevalent cases, 70,042 deaths, and 4.07 million DALYs. From 1990 to 2023, incident cases increased by 24.7%, while the age-standardised incidence rate fell from 29.57 to 25.15 per 100,000 person-years (EAPC, -0.71; 95% CI, -0.83 to -0.59). Age-standardised mortality and DALY rates also declined, with EAPCs of -1.97 and -2.20. Incidence reached a low point around 2010 before rising again, particularly after 2019. The burden was greatest in children and older adults. Higher SDI was associated with lower age-standardised incidence, mortality, and DALY rates (r = -0.59, -0.41, and -0.56, respectively; all P < 0.001). Population growth accounted for most of the increase in case numbers.

Encephalitis remains a substantial health burden in LMICs. Although age-standardised mortality and DALY rates have declined, the growing absolute number of cases, recent upward shift in incidence, and persistent concentration of burden among children, older adults, and lower-SDI settings point to continuing gaps in prevention, surveillance, diagnosis, and care.