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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.