Tuberculosis: the forgotten epidemic that still kills in West Africa

In 2024, tuberculosis once again became the world's leading cause of death from a single infectious agent, with 1.23 million deaths (WHO). Africa pays a disproportionate share: the WHO African Region recorded 404,000 deaths in 2023, including 112,000 among people living with HIV. Yet the paradox is cruel. This disease is cured in more than nine cases out of ten when caught in time, and Africa has posted the steepest decline in mortality of any region in the world since 2015. If it still kills, it is therefore not for lack of knowing how to treat it. It is for lack of finding the patients and for lack of funding the hunt. In West Africa, nearly one tuberculosis patient in four remains invisible to the statistics, and therefore to any treatment, and continues to transmit the bacillus. The epidemic is not forgotten by chance: it is under-diagnosed, under-funded and, as a result, underestimated.

One region, two worlds: Nigeria far ahead, Benin as a model

In West Africa, tuberculosis traces two realities that are barely comparable. At one extreme, Nigeria alone carries a colossal burden: around 499,000 incident cases per year, an incidence of 219 cases per 100,000 inhabitants, the highest of the nine reference countries and one of the heaviest in the world. At the other extreme, Benin records 42 cases per 100,000 inhabitants, more than five times fewer, and Togo 47. Between these two worlds, an intermediate group with a heavy burden stands out: Senegal (133), Ghana (129) and Côte d'Ivoire (103). This contrast cannot be reduced to demographics. It stems from each country's epidemiological history, from the weight of HIV co-infection and, above all, from the ability of health systems to identify patients before they infect those around them.

Twenty years of decline: proof that the epidemic is no fatality

The good news is real and measurable. Over two decades, most West African countries have driven down their tuberculosis incidence. Benin fell from 71 cases per 100,000 inhabitants in 2000 to 42 in 2023, a continuous and steady decline. Ghana followed the same slope, from 216 to 129. Côte d'Ivoire, after a peak of 213 in the mid-2000s, came back down to 103. Across the WHO African Region, tuberculosis mortality dropped by 42% between 2015 and 2023, the steepest fall of the world's six regions, while the number of cases declined by 24% over the same period. This trajectory proves one essential thing: tuberculosis recedes when there is a decision to fight it. It is not a geographic curse, but the product of health systems that are more or less well equipped.

The real bottleneck: finding patients, not curing them

The heart of the West African problem is not therapeutic. When a patient is detected and put on treatment, cure is the rule: the treatment success rate reaches 91% in Benin and lies between 81 and 94% across the sub-region. In other words, medicine does its job. The link that breaks lies upstream, at diagnosis. Across the African Region, an estimated 2.5 million cases occurred in 2023 for only 1.9 million notified: nearly 600,000 patients escape the system each year, close to one in four. These undiagnosed patients are not only victims on borrowed time. Without treatment, each of them keeps transmitting the bacillus to those around them, feeding the epidemic that the statistics believe to be receding. Under-detection is therefore not a counting problem: it is an engine of contagion.

The detection gap between countries is striking, and it directly illuminates the incidence map. Ghana posts the lowest rate of the nine reference countries: barely 44% of estimated cases are diagnosed there, meaning more than one patient in two slips through the net, even though its incidence remains high (129 per 100,000). The link is no accident. Where screening collapses, incidence stalls, because untreated patients keep infecting others. Conversely, Nigeria, Benin, Niger and Togo exceed 70% detection. The message to decision-makers is clear: the main lever available is not a new drug, it is an active screening effort, directed at the populations the system does not see.

The West African problem is not curing tuberculosis, but finding the patients. When a patient is detected, they are cured in more than nine cases out of ten. The tragedy plays out before treatment, not during it.

Mortality, a mirror of detection inequalities

The geography of tuberculosis mortality overlaps almost exactly with that of under-detection. Ghana, last in the screening ranking, records the highest mortality of the nine countries (29 deaths per 100,000 inhabitants, excluding HIV), followed by Nigeria (28). At the other end, Benin, which combines low incidence, good detection and an excellent cure rate, records 5 deaths per 100,000, nearly six times fewer than Ghana. This correlation is no statistical coincidence: it reflects a simple causal chain. An undetected patient is an untreated patient, and an untreated patient is a patient at risk of dying. Mortality is therefore not a measure of the bacillus's virulence, but of the health system's performance against it.

Nigeria's overwhelming weight in the regional equation

No regional strategy makes sense if it ignores Nigeria's weight. With an estimated 499,000 incident cases in 2023, the country alone accounts for 4.6% of global cases and ranks 6th among the most affected countries on the planet. To give the order of magnitude: Nigerian cases alone far exceed the sum of all the other countries in the sub-region combined. Ghana, the second West African epicentre, counts around 43,600 cases, Côte d'Ivoire 32,100, Benin 5,900 and Togo 3,900. This concentration has a major political consequence. Any progress by Nigeria pulls regional indicators upward, and any lag drags them down. The West African fight against tuberculosis is won or lost first in Nigeria, which does not exempt any other country from its responsibility on its own territory.

The Achilles' heel: funding at one-fifth of the need

If the region does not find its missing patients, it is first because it lacks the means. The African Region mobilises only 0.9 billion dollars a year for the fight against tuberculosis, while the need is estimated at 4.5 billion. The annual shortfall therefore reaches 3.6 billion dollars, four dollars missing out of every five. This under-funding is not an accounting detail: it conditions everything else. Without a budget, there are no active screening campaigns in remote areas, no rapid molecular tests deployed at scale, no contact tracing around declared cases. The shortfall figure is, in reality, the price of resignation: it is the sum that separates the current epidemic from an epidemic under control.

Under-funding is paid twice. Once by the health system, which lets patients slip away; a second time by families, who absorb the cost of care. In Africa, 68% of households affected by tuberculosis face so-called catastrophic health expenditure, meaning above one-fifth of their annual income, whereas the WHO's target is to bring this proportion down to zero. This financial burden is a direct brake on seeking care: for fear of ruin, patients delay consultation, interrupt it or give it up, and become sources of contagion. Public under-funding thus generates private under-use, in a loop where the epidemic feeds on the poverty it worsens.

Resistance and HIV: the two aggravations that under-detection feeds

Two factors turn ordinary tuberculosis into a major public-health threat, and both thrive on the fertile ground of under-detection. The first is resistance to anti-tuberculosis drugs. The African Region counts around 60,266 estimated cases of multidrug-resistant or rifampicin-resistant tuberculosis in 2023, but only 22,515 are notified: more than 60% of these cases, the most dangerous and the most costly to treat, remain undetected and untreated. Yet an unmanaged resistant case does not disappear; it spreads, and carries with it strains against which first-line treatments are powerless. Every missed resistant patient mortgages the future effectiveness of the entire therapeutic arsenal.

The second factor is HIV co-infection, which makes Africa the region where the virus weighs most heavily in tuberculosis mortality. Of the 404,000 deaths in the African Region in 2023, 112,000 occurred among people living with HIV, more than one death in four. HIV turns a latent tuberculosis infection, often benign in an immunocompetent subject, into active and rapidly fatal disease. Globally, this coupling kills 150,000 HIV-positive people a year. These two aggravations impose an operational conclusion: screening for tuberculosis without simultaneously screening for HIV and resistance means treating by halves and exposing the patient to the worst.

What national averages hide

National indicators, indispensable for comparing countries, become misleading as soon as it comes to action. Nigeria's incidence, frozen at 219 per 100,000 since 2000 in the World Bank database, illustrates this trap: this apparent stability reflects above all the uncertainty of the estimates, for lack of a recent prevalence survey used in the series, rather than a genuine absence of progress. It also conceals immense internal disparities, between federated states, between towns and countryside, between settled and nomadic populations. Likewise, a flattering national detection rate, such as Nigeria's 74%, masks rural or pastoral pockets where rapid diagnosis has never been available: across the continent, the rapid molecular test reached only 54% of African patients in 2023. The average reassures where the field sounds the alarm.

HIV adds a layer that national rates erase. Tuberculosis contracted by an HIV-positive person has neither the same prognosis, nor the same urgency, nor the same cost as ordinary tuberculosis. The 112,000 African deaths linked to HIV are not evenly distributed: they concentrate where co-infection is frequent and where joint management is lacking. Steering the fight against tuberculosis from national incidence alone means ignoring these fault lines that determine who lives and who dies. Aggregate data says how many patients exist; it says neither where they are, nor why the system does not see them.

• Where are the missing patients? The 600,000 undiagnosed cases in the African Region are not randomly distributed: they lodge in the areas where rapid diagnosis does not reach, which national rates render invisible.
• Who dies and why? Excess mortality concentrates where low detection, HIV co-infection and unmanaged resistance combine, three factors that a national average adds together and conceals.
• Who gives up on care? Behind the figure of 68% of households ruined by the disease hide the families who, for fear of the expense, delay or abandon treatment and become sources of transmission.

The CRAD angle: illuminating the missing patients to target the missing billions

It is precisely in this blind spot that CRAD works. Aggregate statistics say that 600,000 diagnoses and 3.6 billion dollars a year are missing; they do not say where to deploy these resources to save the most lives. Closing this information gap is fieldwork: mapping under-detection zones within each country, assessing real access to rapid molecular tests municipality by municipality, measuring the financial burden that pushes households to forgo care, and documenting the populations the system does not see, migrants, nomads, informal neighbourhoods. Our field surveys, our expertise in digital data collection and our practice of monitoring and evaluation turn a national statistic into an operational map.

The stakes are directly budgetary. Poorly targeted active screening wastes already scarce resources; screening guided by granular data concentrates the effort where the return in lives saved is highest. In a context where four dollars out of five are missing, every franc must be invested at the exact point where it cuts a chain of transmission. This is the promise of a complete chain, from the field to the dashboard: giving states and funders the means to know not only how many patients escape them, but where they are, so that the missing 3.6 billion, the day they are mobilised, are not spent blindly.

A real but fragile decline: do not ease the effort

The global trajectory calls for clear-sightedness. Global tuberculosis mortality has indeed receded, from 1.4 million deaths in 2021 to 1.23 million in 2024, but the slope has flattened and the disease has regained its rank as the leading cause of infectious death. This decline remains suspended on the continuity of funding and screening. In Africa, the 42% drop in mortality since 2015 is a remarkable achievement, but a reversible one: it would take only a disengagement by funders or a slackening of screening for today's 600,000 missing patients to become tomorrow's norm. Tuberculosis is an epidemic that does not forgive inattention. It recedes when it is hunted, and rebounds as soon as it is let go.

Fundamentally, West African tuberculosis is not an unsolved medical problem: we know how to diagnose it, we know how to cure it in more than nine cases out of ten. It is a problem of detection and funding, and therefore a problem of data-driven steering. The countries that make progress, like Benin, are those that find their patients and treat them to the end. Those that stall, like Ghana despite an incidence comparable to that of its neighbours, are those that leave half of their patients in the shadows. Taking back control of the forgotten epidemic means first deciding to see those who go unseen, then funding the hunt where it saves the most lives.

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