Lessons Learned from the epidemiology of Tuberculosis in Nakfa District, Eritrea, 2007– 2021

Abstract

Abstract Background Tuberculosis (TB) remains one of the deadliest diseases in the world. Mitigation of the its impact requires high-quality data on multiple themes. In this analysis, our objective was to provide information on the incidence and spatio-temporal distribution of tuberculosis in one of the remotest districts (Nakfa) in Eritrea. Methodology: In this retrospective observational study, data on patients diagnosed with tuberculosis were captured from 2007–2021 in the Nakfa hospital registry. The crude incidence rate (CIR) and the age-standardized rate (ASR) were analyzed and expressed per 100,000 persons per year. The Joinpoint Regression Program, Version 4.9.0.0 and Arc GIS (v 10.7.1 (Esri, Redlands, CA, USA)) were used to evaluate the temporal trends and spatio-temporal distribution of tuberculosis. Results Of the 2,155 Nakfa district sputum samples collected during the study period, 165 (7.6%) were smear positive for pulmonary tuberculosis (PTB). Smear-negative PTB was diagnosed in 47 individuals and 104 patients with extra-pulmonary TB. Among all these TB patients, 178 were female vs. 138 males. The median age at the time of diagnosis was 32 years (IQR: 20–50). The average annual incidence rate was 55.64 (95% CI 48.2–60.1) cases per 100,000 inhabitants. In the Joint Point Regression model, age adjusted incidence (AAR) increased from 2009 (AAR = 57.96) to 2018 (AAR = 91.67) (p-value = 0.004) and decreased thereafter (AAR = 23.03). The highest AAR of TB was reported in women > 45 years. This corresponded to an annual increase of 11.3% from 2009–2018 (p-value = 0.004) and a decrease of 38.5% in 2018–2021 (p-value = 0.012). The average annual percentage change (AAPC) in the incidence rate was − 6.6% (95%CI: -15.7-3.6). The incidence rate in patients > 65 years demonstrated a significant increase (APC = 16.1%; 95%CI: 8.8–24.0) in the joint point (p-value < 0.001) and a precipitous decline (APC= -33%; 95%CI: -52.3 -6.7) in 2017–2021 (p-value = 0.023). Spatiotemporal analysis demonstrated that TB is largely clustered in areas close proximity to Nakfa Hospital. Lastly, active case finding activities in 2017 and 2018 suggested possible under diagnosis of TB. Conclusion The incidence of tuberculosis in Nakfa district is relatively stable. However, the distribution is largely uneven. Active case-finding activities in 2017 and 2018 suggested that the observed heterogeneity in case density may be associated with underdiagnosis of TB in some subzones in the district. More decentralization of TB care services and intensification of case finding through the expansion of sputum collection are required.