Tuberculosis, an infectious disease caused by the bacterium Mycobacterium tuberculosis, primarily targets the lungs. Although treatable and preventable, it remains a public health challenge across the African continent. The disease’s prevalence is deeply intertwined with various socioeconomic and health factors, creating a complex crisis that claims hundreds of thousands of lives annually.
The Scale of the Epidemic in Africa
The burden of tuberculosis in Africa is immense. In 2022, an estimated 2.5 million people in the African region fell ill with TB, a quarter of new cases worldwide. The continent also accounted for over a third of all TB deaths globally, with approximately 424,000 people succumbing to the disease.
This burden is not evenly distributed, with nations like South Africa, Nigeria, and the Democratic Republic of Congo facing severe epidemics. Eastern and Southern Africa have historically been the epicenter of the disease. However, these subregions have made notable progress, nearly halving the incidence rate between 2000 and 2023.
Despite this progress, the prevalence of TB remains high and varies significantly across nations. For example, older surveys showed prevalence ranging from 119 per 100,000 in Rwanda to 638 per 100,000 in Zambia. The high volume of cases places an enormous strain on already fragile healthcare systems.
Key Drivers of Tuberculosis Transmission
The link between tuberculosis and the Human Immunodeficiency Virus (HIV) is a primary driver of the epidemic in Africa. People with HIV have compromised immune systems, making them 20 to 30 times more likely to develop active TB. A healthy immune system can often contain the TB bacteria in a latent state, but the weakened defenses in a person with HIV allow the infection to become active and transmissible.
This biological vulnerability is amplified by the high prevalence of HIV in many parts of the continent. In 2022, an estimated 25.6 million people in Africa were living with HIV. The convergence of these two epidemics means HIV facilitates the spread of TB, and TB is a leading cause of death among people with HIV.
Socioeconomic factors also contribute to TB transmission. Malnutrition, a consequence of poverty, weakens the immune system and increases susceptibility to active disease. In 2022, an estimated 2.2 million new TB cases globally were linked to undernourishment.
Overcrowded living conditions in urban centers and informal settlements facilitate the transmission of the bacteria. When an individual with active pulmonary TB coughs, they expel bacteria into the air. These environments, especially without adequate ventilation, create ideal settings for sustained transmission.
Diagnostic and Treatment Hurdles
Diagnostic Challenges
A significant obstacle in controlling tuberculosis is the difficulty in accurately and rapidly diagnosing the disease. The primary diagnostic tool has been sputum smear microscopy, which is inexpensive but can be unreliable. This method frequently yields false-negative results, especially in patients co-infected with HIV who have lower concentrations of bacteria in their sputum.
Newer molecular diagnostic tools, such as the GeneXpert system, offer much higher accuracy and can detect resistance to a first-line TB drug. However, their implementation is hampered by cost and the need for stable electricity and trained personnel. As of 2023, limited access to rapid diagnostics remains an issue, reaching only 54% of TB patients in the region.
Drug-Resistant Tuberculosis
The spread of drug-resistant TB (DR-TB) is a threat to public health. Multidrug-resistant TB (MDR-TB) is caused by bacteria resistant to at least two potent first-line drugs. Extensively drug-resistant TB (XDR-TB) is a more severe form with resistance to additional second-line drugs, leaving few treatment options.
Treating these resistant forms is a challenge. The regimens are much longer, lasting for months or years, compared to the standard six-month course for drug-susceptible TB. These treatments involve medications that are more toxic, with severe side effects. The cost of treating DR-TB is also substantially higher, placing a financial burden on patients and national health systems.
Strategies for Control and Prevention
A central pillar of TB control is the Directly Observed Treatment, Short-course (DOTS) strategy. This approach requires a healthcare worker or volunteer to observe patients taking their medication to ensure adherence to the full treatment course. This is necessary to cure the disease, prevent drug resistance, and stop transmission. National TB programs implement this strategy by managing drug distribution, overseeing patient care, and reporting cases.
Prevention Efforts
Prevention efforts include the Bacille Calmette-Guérin (BCG) vaccine, typically administered to infants in countries with high TB prevalence. Its primary benefit is preventing severe forms of the disease in children, such as TB meningitis. The BCG vaccine offers limited protection against pulmonary TB in adolescents and adults, the most common and transmissible form.
International Support
International partnerships significantly support the fight against TB in Africa. Organizations like The Global Fund and the Stop TB Partnership provide financial resources and technical assistance to national programs. This support is used for purchasing diagnostics and medicines, strengthening health systems, and funding research for new tools.