Spatial epidemiology of Japanese encephalitis virus and other infections of the central nervous system in Lao PDR (2003 – 2011): a retrospective analysis

Abstract

<jats:p>Central nervous system (CNS) infections are important contributors to morbidity and mortality worldwide, but the causative agents for ~50% patients are never identified. Here we present the results of a spatial analysis of CNS infections in Lao PDR (2003 − 2011). Hospitalizations for suspected CNS infection were recorded at Mahosot Hospital in Vientiane and tests for a large panel of pathogens were performed. All home villages were geocoded using patient records and official Lao PDR census data. The spatial distributions of CNS infections were analyzed by major diagnoses. Summary statistics and logistic regressions were used to test for associations between geographic, environmental, and demographic variables and diagnoses. Out of 1,065 patients, 450 (42%) were assigned a confirmed diagnosis. Japanese encephalitis virus ((JEV); n=94) and Cryptococcus spp. (n=70) were the most common infections. Patients undergoing diagnostic LP for suspected CNS infections lived closer to major roads than would be expected by chance alone. JEV was the most spatially dispersed, peaked in the rainy season and was most common among children. JEV patients came from villages that had higher surface flooding during the same month as admission and, in comparison to the home villages of other patients, came from villages at higher elevation. Cryptococcus spp. infections clustered near Vientiane and among adults. Geographic and financial access to healthcare may explain the close proximity of these patients to major roads and also suggest that these hospital data vastly underestimate the true community burden of CNS infections. As Lao PDR is undergoing major developmental and environmental changes, the space-time distributions of the causative agents of CNS infection will also likely change. There is a major need for increased diagnostic abilities; increased access to healthcare, especially for rural populations; and for increased surveillance throughout the nation.</jats:p>