Spatiotemporal Distribution of Tuberculosis in the Oromia Region of Ethiopia: A Hotspot Analysis

Abstract

Tuberculosis (TB) is a major public health concern in low- and middle-income countries including Ethiopia. This study aimed to assess the spatiotemporal distribution of TB and identify TB risk factors in Ethiopia's Oromia region. Descriptive and spatiotemporal analyses were conducted. Bayesian spatiotemporal modeling was used to identify covariates that accounted for variability in TB and its spatiotemporal distribution. A total of 206,278 new pulmonary TB cases were reported in the Oromia region between 2018 and 2022, with the lowest annual TB case notification (96.93 per 100,000 population) reported in 2020 (i.e., during the COVID-19 pandemic) and the highest TB case notification (106.19 per 100,000 population) reported in 2019. Substantial spatiotemporal variations in the distribution of notified TB case notifications were observed at zonal and district levels with most of the hotspot areas detected in the northern and southern parts of the region. The spatiotemporal distribution of notified TB incidence was positively associated with different ecological variables including temperature (β = 0.142; 95% credible interval (CrI): 0.070, 0.215), wind speed (β = -0.140; 95% CrI: -0.212, -0.068), health service coverage (β = 0.426; 95% CrI: 0.347, 0.505), and population density (β = 0.491; 95% CrI: 0.390, 0.594). The findings of this study indicated that preventive measures considering socio-demographic and health system factors can be targeted to high-risk areas for effective control of TB in the Oromia region. Further studies are needed to develop effective strategies for reducing the burden of TB in hotspot areas.

Keywords: Ethiopia; Oromia; TB case notification; spatiotemporal; tuberculosis.

Figure 1

Map showing the study area, Oromia region, Ethiopia.

Figure 2

Sex- and year-standardized TB case notification (SIR) of TB cases at the district level in the Oromia region, 2018–2022. In districts with an SIR around one (color yellow), the number of TB cases observed is the same as the number of expected cases. In districts where SIR > 1 (color red), the number of TB cases observed is higher than the expected cases. Districts where SIR < 1 (color blue and gray) have fewer observed TB cases than expected.

Figure 3

Hotspot maps showing the spatial clustering of tuberculosis incidence in the Oromia region, based on the Getis–Ord Gi* statistics, between 2018 and 2022.

Figure 4

Cluster and outlier maps showing the tuberculosis incidence ratio in the Oromia region, based on Anselin Local Moran’s I analysis, between 2018 and 2022.

Figure 5

Relative risk (RR) of tuberculosis at the district level in Oromia based on the posterior spatially structured random effects, 2018-2022. The relative risk (RR) quantified whether a district has a higher (RR > 1) or lower (RR < 1) risk than the average risk in the region’s population. For example, if (RR = 2), the risk of the district is two times the average risk in the region’s population.