National differences and time trends of tuberculosis in West Africa, 1990 – 2012

Abstract

Background: Tuberculosis remains an important cause of mortality and morbidity in West Africa largely due to years of healthcare neglect. This thesis, therefore, aims to investigate national differences and time trends of tuberculosis in West Africa between 1990 and 2012. Methodology: Descriptive epidemiology is the thesis methodology. Data were extracted from various electronic sources including the World Health Organization, the Global Burden of Disease project, and other sources. Other reports were accessed through the University of Auckland library. Data analysis was carried out with stata12, and national differences and time trends investigated using descriptive statistics. Results: In 2012, West Africa tuberculosis (TB) incidence (all forms) was estimated at 395, 000 cases, and a prevalence (all forms) of 617, 000. In the same year, mortality from TB (excluding TB cases with Human Immunodeficiency Virus (TBHIV)) was reported at 61, 000, and mortality in TB patients with HIV was 29, 000. In 2010, West Africa lost 3.7 million Disability Adjusted Life Years due to TB. The burden of tuberculosis per capita falls most heavily on Sierra Leone, followed by Mauritania, Liberia, and The Gambia. Between 1990 and 2012, TB trends for Sierra Leone, measured in terms of incidence, prevalence, and mortality, were higher than all other countries, and in some instances quadrupled the regional average. For instance, in 1990, TB prevalence (all forms) for Sierra Leone was reported at 500 per 100, 000 population; and in 2012, it was reported at 1300 per 100, 000 population, an increase of 800 per 100, 000 population per year between 1990 and 2012. Although the rise in TB frequency has halted in Sierra Leone, Mauritania, Guinea Bissau, and The Gambia continue to show an upward trend. The rate of increase in TB in Mauritania, over the past 22 years, is particularly worrying. This is because, Mauritania TB trends do not show any indication that they will start to level-off soon. When TB trends were investigated by colonial histories, Francophone West Africa appeared to have a marginal advantage in Multidrug Resistance TB case detection and management, possibly due to better laboratory capacity infrastructure than the Anglophone and Portuguese former colonies. There appears to be no colonial differences in other TB indicators investigated in this thesis. Nevertheless, TB trends have decreased by half their 1990 levels in line with the Millennium Development Goals in Niger, Guinea, and in four of the five countries described in this thesis as Low TB Frequency Countries (LTBFC). Across West Africa, TB mortality is higher in males than in females, but in Nigeria, more deaths were reported in women than in men. Throughout the region, the quality and reliability of these findings are compromised by the lack of Vital Registration systems, the high frequency of underreporting, and common misdiagnosis. Conclusion: Acknowledging the issues with data quality, it is evident nevertheless that TB rates remain very high in many countries in West Africa and the impact is greater in men than in women. The key implication from this thesis is that TB will likely remain a significant health problem in West Africa beyond the 2050 Millennium Development Goals target.