Malaria in Nepal: A Spatiotemporal Study of the Disease Distribution and Challenges on the Path to Elimination.

Abstract

Malaria incidence (MI) has significantly declined in Nepal, and this study aimed to investigate the spatiotemporal distribution and drivers of MI at the ward level. Data for malaria cases were obtained from the National Surveillance System from 2013 to 2021. Data for covariates, including annual mean temperature, annual mean precipitation, and distance to the nearest city, were obtained from publicly available sources. A Bayesian spatial model was used to identify factors associated with the spatial distribution of MI. Between 2013 and 2021, 7278 malaria cases were reported in Nepal, with a crude incidence rate of 3.0 cases per 100,000 person-years at risk (PYR). MI showed a seasonal variation, with the highest number of cases reported between May and September. The annual MI decreased in recent years from 1.9 per 100,000 PYR in 2018 to 0.1 per 100,000 PYR in 2021. Spatial clustering of MI was observed at the ward level, with most hotspot areas detected in the western Terai plains and upper river valley (URV) areas. Incidence was associated with annual mean precipitation in mm (β = 0.201; 95% CrI: 0.042, 0.360). The shift of the malaria hotspots to the URVs presents a challenge for implementing timely prevention and control activities.