Life expectancy: historic gains, and a double burden that threatens them

In thirty-four years, a child born in Niger has gained almost twenty years of life expectancy: from 41.7 years in 1990 to 61.4 years in 2024, according to the World Bank. It is one of the fastest health advances ever recorded on the planet, and it is far from isolated: across West Africa, children survive better, mothers die less often, epidemics recede. Yet this success carries a new threat within it. As infections retreat, chronic diseases (diabetes, hypertension, cancers) surge without health systems being equipped to confront them. The region is thus entering a phase in which two burdens coexist, the old one not yet extinguished, the new one already installed. The question is no longer only about living longer, but about whether these added years will be years in good health, or years of untreated illness, in care systems that, for lack of resources and data, often advance blindly.

A generation of gains, a gap narrowed but not closed

The figures tell, first of all, a story of success. Average life expectancy in Sub-Saharan Africa (excluding high-income countries) rose from 50.0 years in 1990 to 62.8 years in 2024, nearly thirteen years of life gained in a single generation. The gap with the world average (73.5 years) remains real, but it has narrowed as the region closed part of its lag. Behind this regional average, every West African country made progress, none regressed over the long term, and several now approach the standards of middle-income countries. Few regions of the world have, in a single generation, added more than a decade to the average length of a human life: this outcome did not fall from the sky, it is the product of public health policies pursued in sustained fashion, campaign after campaign.

At the top, Senegal reaches 68.9 years in 2024, the highest value among the nine reference countries, followed by Ghana (65.7 years). These two coastal countries are approaching a threshold few would have anticipated thirty years ago. At the other end, Nigeria plateaus at 54.6 years, more than fourteen years below Senegal, even though it concentrates the demographic weight of the sub-region. Benin stands at 61.0 years, in the regional average. This dispersion, more than fourteen years between the first and the last, is a reminder that a single regional space is home to deeply different health realities: fourteen years is roughly a whole generation of lag, within an economic space that is nonetheless integrated.

The proof through time: Niger, champion of gains

The comparison over time is even more illuminating than the comparison between countries. Niger, long one of the countries where people lived the shortest lives in the world, achieved the strongest progression in the sub-region: +19.7 years between 1990 and 2024. Nigeria, by contrast, gained only 8.9 years over the same period (from 45.7 to 54.6 years). This difference in pace is decisive: it shows that the starting point does not determine the trajectory, and that a country can accelerate sharply when public health interventions finally reach the ground. In other words, geography and income condemn no one: between two Sahelian neighbours, the one worst off in 1990 ended up overtaking the most populous, not by miracle but through the consistency of the effort.

Nigeria's lag deserves a pause. The continent's most populous country, it drags down not only its own average but also the regional aggregate. Its lag is not a geographic fate: Niger, a poorer Sahelian neighbour, did better. It is therefore in the organisation and financing of care, not in the climate nor in income alone, that the explanation must be sought. As long as this country, which accounts for nearly a fifth of the continent's population, does not accelerate, no flattering regional average will lastingly mask the absolute number of lives at stake.

The engine of the gains: the collapse of child mortality

Where do these added years come from? For the most part, from a single mechanism: the survival of the very young. Life expectancy at birth is mechanically very sensitive to mortality in the early years, because a death at age five subtracts from the average the equivalent of an entire life that will not have been lived. And that mortality has collapsed. Mortality of children under five has been divided by nearly four in Senegal, falling from 137 per 1,000 births in 1990 to 36.5 in 2024, and by three in Niger, from 332 to 111 per 1,000. Every child who survives to age five adds decades to the national average: it is the most powerful mechanism of any life expectancy gain, and it is the one that operated at full force in West Africa.

The causes of this progress are well known and convergent: insecticide-treated nets against malaria, the expansion of immunisation, HIV treatment, improved maternal and neonatal care, better access to water and nutrition. These are high-return public health interventions, inexpensive and well targeted, which produced a mass effect. Niger alone illustrates what sustained campaigns can accomplish in a single generation. This effectiveness stems from the nature of the enemy: an infectious disease is fought through standardised gestures, reproducible at scale, which a campaign can carry to the last village. It is this logic of mass intervention that drove down child deaths; it is not the one that will make it possible to contain the chronic diseases of tomorrow.

Every child who passes the milestone of five years adds decades to the national average. It is here, and not in cutting-edge medicine, that the first battle of life expectancy was won.

The turning point: the silent rise of chronic diseases

As infections retreat and the population ages, a second mortality profile takes hold. Non-communicable diseases (diabetes, hypertension, cardiovascular diseases, cancers, chronic respiratory conditions) gain ground, driven by urbanisation, changing diets, sedentary lifestyles and lengthening lives. This is what demographers call the epidemiological transition. Across Sub-Saharan Africa, the share of deaths attributable to these chronic diseases rose from 24% in 2000 to 37% in 2019, and the WHO projects that they will become the leading cause of death on the continent by 2030. The shift is not a distant scenario: it is already under way, and its speed often surprises planners accustomed to an infectious enemy they still believed to be the priority.

This rise has a telling numerical face: diabetes. The WHO estimates that the number of people living with diabetes in Africa could rise from 19 million in 2019 to 47 million in 2045, nearly a tripling in a quarter of a century. Yet these conditions are not treated like an epidemic: they require early screening, long-term follow-up and permanent treatment, functions that most West African health systems, structured for the infectious emergency, have not yet developed at scale. The difference is structural: an epidemic flare-up is extinguished by a one-off campaign, but a chronic disease is managed only by accompanying the patient throughout their life. Moving from a campaign logic to a logic of permanent follow-up is arguably the deepest change that the region's health systems must undertake.

The new front: the early death of adults

The shift in the burden is read not only in the share of deaths, but in the age of those who die. Where the infectious burden struck mainly infants, chronic disease strikes the adult in the prime of life. Across Sub-Saharan Africa, it is estimated that about 1.6 million people aged 30 to 70 die prematurely each year from a non-communicable disease, and the WHO projects that this figure could reach 3.8 million per year by 2030. These premature deaths represent the majority of deaths linked to chronic diseases: they strike parents, workers, breadwinners, at the very moment when their disappearance disrupts households and the economy most heavily.

This early mortality has a twofold consequence. A health consequence, because it erodes life expectancy no longer from the bottom, on the side of children, but from the middle, at an age when the gains should already be secured. An economic consequence, because it deprives the active population of its most experienced members, in economies already constrained in skilled human capital. The fight against chronic diseases is therefore not a luxury of rich countries: in a young region, it protects precisely the generation that must carry development forward.

What the averages hide: a north-south divide

The regional average hides the essential: West Africa is in fact living through two epidemiological transitions at opposite speeds, and a single map never shows it. In the Sahel, communicable, maternal and nutritional diseases remain dominant: they still account for 65.7% of deaths in Niger and 63.7% in Nigeria in 2021. The transition there is unfinished: the first burden, the old one, still weighs with all its force, and diverting resources prematurely toward chronic diseases there would be a calibration error.

On the coast, the picture is reversed. In Senegal, chronic diseases already account for 47.7% of deaths in 2021, against 39% for infectious diseases; in Ghana they reach 46.8%. These countries have entered the second mortality regime. Two neighbouring countries can therefore call for diametrically opposed public health priorities: strengthening the fight against infection here, building chronic care pathways there. A single national indicator, and even more so a regional average, would erase this reality and lead to poorly calibrated policies. It is one of the most frequent traps in public decision-making: to believe that an integrated region calls for a homogeneous response, when its members are not at the same stage of a single trajectory.

The rise over time: no one escapes it

If the divide is spatial, the trend is universal. Between 2000 and 2021, the share of chronic deaths increased in every country of the sub-region, including those in the Sahel still dominated by infection. In Senegal, this share rose from 28.8% to 47.7%; in Benin, from 26.5% to 36.2%; even in Niger, the country least advanced in the transition, it climbed from 13% to 23.9%. In other words, no country is going backward: the only variable is the speed, and the point where each stands on the same trajectory. This universal character is a strategic signal: even the Sahel countries, absorbed by the infectious fight, must begin right now to prepare their systems for the chronic wave which, among them too, is only rising.

The sinews of war: underfunded health systems

Waging two battles at once requires resources, and that is precisely where the shoe pinches. Health financing in the region remains well below needs. In 2021, Sub-Saharan Africa spent only about 92 dollars per person per year on health, roughly a fifth of what was spent by the next least well-endowed region, the Middle East and North Africa (about 379 dollars). Of the 47 countries in the WHO African Region, only a handful reached, over the 2012-2020 decade, the recommended threshold of about 249 dollars per person. Steering an epidemiological transition with budgets so constrained is like changing fronts without reinforcing the troops.

Political commitment, too, has been slow to follow. Through the Abuja Declaration of 2001, African states set themselves the target of devoting at least 15% of their public budget to health. Yet over the 2014-2020 period, a single country on the continent, South Africa, reached and maintained this target; in several countries, health's share of public spending remains between 2% and 12%. Compounding this weakness is the weight of spending paid directly by households: when out-of-pocket costs exceed the prudent threshold of 15 to 20% of current spending, it is the poorest patients, often those who carry the double burden, who forgo care or fall into poverty to be treated. Financing is therefore not a secondary technical matter: it is the very condition of universal health coverage.

The cost of inaction: reversible gains

The double burden directly threatens the gains achieved. Two dangers compound each other. On one side, the first burden is not extinguished: under-five mortality remains very high in the Sahel, at 110.7 per 1,000 in Niger and 115.6 in Nigeria in 2024, more than three times the level of Senegal. Any easing of the anti-infectious effort, as glimpsed during the pandemic, can send these curves back up. On the other, the second burden strikes working-age adults, at the productive core of young societies, and is paid in years of active life lost as much as in health spending.

The budgetary cost is the crux of the problem. Fighting both burdens at once requires more resources, at a time when the region's health budgets remain strained. Chronic diseases are costly by nature: they entail permanent follow-up, lifelong medication, technical facilities for screening. Without anticipation, they will impose themselves through emergency, at the stage of complications, where treatment is most expensive and least effective. A diabetes detected early is managed with a few francs of medication and advice; the same diabetes discovered at the stage of kidney failure or amputation costs sums beyond comparison, for a far poorer outcome. Anticipating is expensive; enduring costs more.

Living longer, but in better health?

Gaining years is not enough if they are years of illness. That is the whole issue of healthy life expectancy (HALE), which measures the years lived without major disability. The news is rather encouraging: in Nigeria, HALE reached 55.2 years in 2021, up 9.2 years since 2000. The added years are therefore not, so far, only years of morbidity. But this indicator, precisely, is the one most threatened by the transition under way: chronic diseases lengthen the period during which one lives with illness rather than dying quickly. Without long-term care systems, the gap between total life expectancy and healthy life expectancy risks widening, and years would then be gained at the price of added suffering and dependence.

A note of caution is needed in reading here: the HALE data come from the WHO and are not directly comparable term for term with the World Bank's life expectancy, since methodologies and reference years differ. These are orders of magnitude, not arithmetic equalities. This very limitation argues for national systems capable of producing, continuously and coherently, the morbidity indicators that most ministries lack today. As long as only the length of life is measured and not its quality, only half the problem is being steered.

A transition with a woman's face

The epidemiological transition is not gender-neutral, and ignoring this leads to poorly targeted action. Women bore a large share of the gains from the first battle, through maternal and neonatal care, but they are also on the front line of the second. They often combine greater exposure to certain risk factors, linked to social norms and precariousness, with more difficult access to screening and care, for lack of time, of their own resources or of suitable services. Yet most of the burden of chronic diseases, as of caring for the sick, rests on them, in the household as in the health system, where they make up the bulk of front-line staff.

The problem is that this dimension remains largely invisible in national statistics: mortality and morbidity indicators are rarely broken down by sex with the granularity needed to guide programmes. Without disaggregated data, a screening programme for hypertension or cervical cancer does not know whether it really reaches the women it targets, at what age, or in which territories. The question of gender is therefore not only a matter of equity: it is a condition of the effectiveness of health policies, and an area where CRAD has built concrete expertise, notably through the regional WOCEWA project on gender equality in the ECOWAS countries.

The CRAD angle: you can only steer what you measure

The epidemiological transition is, before being a medical challenge, a data challenge. Steering two burdens at once presupposes knowing, at any moment, what people die of, at what age and in what place. Yet that is precisely what few national systems produce continuously. Civil registration is often incomplete, causes of death poorly coded, chronic morbidity data almost absent. The figures themselves are a reminder: the World Bank's communicable/non-communicable splits (latest year 2021) and the WHO's regional estimates (37% chronic diseases in 2019) differ according to models and years, for lack of a unified statistical foundation. To decide in such conditions is too often to extrapolate from international models rather than to measure one's own reality.

This is the heart of CRAD's work in public health. Designing and conducting the field surveys that document the real morbidity burden; building the monitoring and evaluation systems that track indicators campaign after campaign; producing the geolocated and disaggregated dashboards (by cause, by age, by sex, by territory) that allow ministries and funders to see both burdens simultaneously. Our experience with large population surveys (of the DHS and MICS type), acquired alongside former staff of the INSAE, anchors this capacity in practice. A health policy that sees only a national average will allocate its resources blindly; one that has a fine-grained map can concentrate every franc where it saves the most years of life.

• See both burdens at once. Without cause-of-death data, a Sahel country may underestimate the rise of diabetes or hypertension until complications saturate the hospitals.
• Go below the national average. The same screening budget does not produce the same effect depending on whether it targets urban areas where chronic diseases are exploding or rural areas still dominated by infection.
• Disaggregate by sex and by age. Risk factors and access to care differ sharply between women and men, between towns and countryside: without these breakdowns, programmes miss their audience.
• Link data to financing. With budgets so constrained, every franc spent must be guided by evidence; measuring the return on interventions is the only way to justify and optimise their use.
• Measure over time. A transition is steered over ten to twenty years; it requires repeated series, not isolated snapshots.

A health policy that sees only a national average will allocate its resources blindly. One that has a fine-grained map can concentrate every franc where it saves the most years of life.

At heart, West Africa has succeeded in the first half of the journey: it has learned to keep its children alive. The second half will be harder, for two battles must now be waged at once without letting go of the first, and it must be done with resources that are counted. The countries that succeed will not necessarily be the richest, but those that can look their mortality in the face, cause by cause and territory by territory, and sustain that effort of measurement over a generation. Living longer was a public health victory; living longer in good health will be a victory of data.

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