Spatiotemporal Trends and Distributions of Malaria Incidence in the Northwest Ethiopia

Abstract

Understanding and extracting noticeable patterns of malaria surveillance data at the district level are crucial for malaria prevention, control, and elimination progress. This study aimed to analyze spatiotemporal trends and nonparametric dynamics of malaria incidences in northwest Ethiopia, considering spatial and temporal correlations. The data were analyzed using count regression spatiotemporal models under the Bayesian setups, and parameters were estimated using integrated nested Laplace approximations (INLA). The region had a declining linear trend, and the average annual malaria incidence rate was 24.8 per 1,000 persons between 2012 and 2020. The malaria incidence rate was decreased by 0.984 (95% CI: 0.983, 0.986) per unit increase in months between July 2012 and June 2020. Districts found in the western and northwestern parts of the region had a steeper trend, while districts in the eastern and southern parts had a less steep trend than the average trend of the region. Compared to the regional level trend, the decreasing rate of malaria incidence trends was lower in most town administrations. The nonparametric dynamics showed that the monthly malaria incidence had a sinusoidal wave shape that varied throughout study periods. Malaria incidence had a decreasing linear trend changed across districts of the study region, and the steepness of trends of districts might not depend on incidences. Thus, an intervention and controlling mechanism that considers malaria incidences and district-specific differential trends would be indispensable to mitigate malaria transmission in the region.

Figure 1

Study area map showing districts in the Amhara national regional state, Ethiopia in 2012.

Figure 2

Total malaria cases by year, age group, months, plasmodium species, seasonal variation, and annual trends in the Amhara region, Ethiopia, between July 2012 and June 2020. (a) Monthly malaria cases and trends. (b) Total malaria cases by age groups. (c) Total confirmed cases by plasmodium species. (d) Monthly variations in the annual trends of malaria cases.

Figure 3

Spatial and temporal distribution of malaria incidences of districts in Amhara region, Ethiopia between 2012 and June 2020.

Figure 4

The estimated differential trends of districts with their corresponding posterior probabilities and spatial effects in northwest Ethiopia between 2012 and 2020. (a) Differential trends and the values within the map are posterior probabilities. (b) Estimated spatial effect for each district.

Figure 5

Posterior temporal trends of malaria incidence in the Amhara region, Ethiopia, between 2012 and 2020.