What's next for tuberculosis control in sub-Saharan Africa?

The recent study from Malawi's Ministry of Health adds to an emerging body of literature from sub-Saharan Africa suggesting that antiretroviral therapy (ART) scale-up reduces the population burden of tuberculosis (TB).^1,2 ART has this effect because it reduces the individual risk among people with human immunodeficiency virus (HIV) infection of developing tuberculosis and of transmitting HIV.³ This reduces both the number of people with HIV who develop TB and the number of people with HIV at risk of developing TB. However, people with HIV achieving viral suppression and immune recovery on ART may have higher rates of TB than people without HIV.⁴ Isoniazid preventive therapy could reduce the risk of TB further among people with HIV on ART.⁵ Systematic implemention of infection control measures such as ventilation, personal protective equipment and adequate spacing in all health facilities is required to reduce the risk of TB in all people, irrespective of HIV status. As countries in Sub-Saharan Africa improve ART coverage and implementation of the Three I's for HIV/TB, they will have to explore what else needs to be done to reduce the burden of TB in their population.

Prompt diagnosis and treatment of active TB remain the foundation of an effective TB response. In recent years, the population effects of achieving high case detection and treatment success rates may have been masked by low ART coverage in sub-Saharan Africa. Given the emergence of drug-resistant TB and the high burden of smear-negative TB, new diagnostics and drugs may be needed to reduce the TB burden in some settings. This may include Xpert^TM MTB/RIF and bedaquiline.⁶ National surveillance will be helpful in understanding the relative contribution of achieving high coverage of TB diagnosis and treatment on individual and population outcomes.

Many countries are going through epidemiological transition. Controlling emerging risk factors for developing TB, such as diabetes, alcohol use and smoking, may require collaboration across programmes. This could include expanding screening, counselling and access to essential interventions. Many countries are also urbanising and facing inequitable economic development. These trends may have implications for TB risk among people of low socio-economic status due to 1) increased exposure to TB through crowded living and working conditions, 2) malnutrition, 3) limited knowledge about protective health behaviours, 4) use of solid fuels for basic energy needs and 5) limited access to health services.⁷ Social development programmes and achieving universal health care coverage may thus have important effects on TB control.