January 15, 2026
In 2021, around 1.25 million people died from diarrheal diseases. Around a third of these deaths were children.
Two main factors explain why so many children still die from diarrhea, especially in poor countries: the persistence of risk factors such as poor sanitation and unsafe water, and the lack of access to effective treatment.
Here, I want to focus on the second factor: access to a particularly effective treatment, known as oral rehydration therapy (ORT), which is essentially a mixture of clean water, salts, and sugar. Simple as it may sound, researchers writing in the medical journal The Lancet called ORT “potentially the most important medical advance of the 20th century.”
The chart shows how often this treatment is used in a selection of African countries. This is based on household surveys asking caregivers of children under five who recently had diarrhea whether they received ORT.
There are large gaps: in Chad and Cameroon, fewer than one in five children with diarrhea received the treatment. This reflects a mix of challenges, including low awareness of its benefits and expensive or inconsistent supply.
Importantly, though, the chart also shows that rates are much higher in Sierra Leone, where around 85% of children received ORT. This shows that much higher coverage is possible. Sierra Leone has implemented several successful policies, including free treatment for children.
Not every child with diarrhea needs this treatment — some recover without it, depending on their health and circumstances. But ORT is cheap, safe, and easy to give. In low-income settings, especially, offering it widely as a cheap preventive measure can make a big difference for those who need it.
Today
In every region of Africa, hunger is more prevalent than a decade ago.
The chart shows the increase in the share of the population that is undernourished, comparing 2014 and 2024 (the most recent year available). These estimates come from the Food and Agriculture Organization of the United Nations.
The situation across Africa is dire. In Middle Africa, where hunger is most acute, almost 1 in 3 people are undernourished. In Eastern Africa, the figure is roughly 1 in 4. Across Africa as a whole, it's 1 in 5.
This marks a reversal of a longer positive trend: over the preceding decades, hunger had been falling across much of the world, including parts of Africa. That progress has now stalled or gone into reverse. Conflict, extreme weather, and the economic disruption of the COVID-19 pandemic have all contributed.
April 11
The concept of “leapfrogging” is popular in development. It suggests that, as they develop, lower-income countries can skip intermediate technologies or systems and go straight to the modern equivalent.
One example of this is the use of landlines and mobile phones.
The landline telephone was invented in 1876 and became a dominant form of communication across Europe and North America. As you can see in the chart, it was increasingly adopted in the United States and the United Kingdom throughout the 20th century.
However, mobile phone adoption increased rapidly in the 1990s, and landlines have declined since the millennium. Mobile phones have become a substitute.
But many countries have almost skipped landline adoption entirely. Ghana and Nigeria are good examples: landline subscriptions have remained extremely low, and instead, mobile phone adoption has exploded.
April 9
Even after years of working with global health data, one statistic that I’m always struck by is the number of people who die by suicide every year. In 2023, it was estimated to be around three-quarters of a million.
That means suicides account for more than 1 in every 100 deaths in the world.
But a world where so many die from suicide is not inevitable. We know this because global suicide rates have fallen by an estimated 40% since the 1990s.
You can see this in the chart: rates have fallen from 15 to 9 deaths per 100,000 people over the last thirty years.
The large differences between countries also suggest that there are things that can be done to reduce this number even further.
April 7
Some technologies central to the clean energy transition depend on rare earth elements. The permanent magnets found in many electric vehicle motors and wind turbine generators rely on them. They are also used in some military hardware.
China dominates global production of rare earths; in 2024, it accounted for nearly 70% of the global total.
But the picture is not as concentrated when you examine which countries have rare-earth reserves. That is what the chart shows, plotting production and reserve shares side by side. China still holds the most known reserves, but at 49%, this is substantially lower than its production share.
Brazil holds 23% of reserves and is barely mining them. India, Vietnam, and Russia also hold significant reserves, but only a small fraction of current output.
The large gap between where reserves are located and where mining occurs partly reflects China's early investment in mining infrastructure and processing capacity, which other producers have not yet matched. Other countries hold the geological potential but have not yet developed the infrastructure to convert it into production at scale.
April 4
Child mortality rates in China have fallen from more than 20% in 1950 to less than 1% today.
But this steady progress was interrupted in the late 1950s during the “Great Leap Forward”. This was China’s national plan to industrialize rapidly, but it resulted in widespread famine and economic turmoil.
As the chart shows, child mortality rates spiked in China over this period, with up to one in three children dying before reaching the age of five. This change was so dramatic that it is also clearly visible in the global trend.
This data comes from the UN’s World Population Prospects.
April 2
Around 4 in 10 women worldwide live in countries where abortion is illegal or highly restricted. But these bans do not stop abortions completely; many women still get them, but in unsafe and unsanitary conditions.
A study published in The Lancet estimated that 45% of abortions globally are unsafe. In some regions, the share is estimated to be around three-quarters. You can see this in the chart.
This data is around ten years old, but represents the latest estimates available (suggesting that this topic gets very little attention).
Unsafe abortions dramatically increase the health risks for women. Safe abortions have very low mortality rates, typically below 1 death per 100,000 abortions.
In regions where the majority of abortions are unsafe, mortality rates can be several hundred times higher; in Western and Middle Africa, around 1 in 200 abortions result in the woman dying.
It’s estimated that approximately 8% of maternal deaths in the world are caused by unsafe abortions. That’s 23,000 women every year.
March 31
Depression, anxiety, and other mental health problems are common everywhere. They are not confined to any particular income level.
But access to care is rare. In much of the world, people who struggle with their mental health have almost no psychologists or psychiatrists to turn to.
Mental health care is scarce in all places, but it is much scarcer in poor countries. Governments in high-income countries spend about $66 per person per year on mental health care, as the chart shows. In low-income countries, that figure is $0.04.
This gap in spending reflects a gap in people. As the WHO’s latest Mental Health Atlas highlights, there is roughly one psychiatrist per million people in low-income countries. High-income countries have 70 times more.
A recent study in the Lancet Psychiatry estimated that globally, only 9% of people with major depressive disorder receive a “minimally adequate treatment”. In high-income countries, it is 27%; in Sub-Saharan Africa, just 2%.
Hundreds of millions of people in poorer countries live with treatable conditions and have no access to a psychologist or psychiatrist. It is one of the largest gaps in global health — and one that receives remarkably little attention or funding.
There are efforts to close this gap without waiting for the workforce to catch up. One approach is to train lay counsellors — people without formal clinical qualifications who learn to provide psychological support. Randomized trials in India and Zimbabwe have shown this can be effective for depression.
Another approach is to use technology: apps and, increasingly, AI-based tools that can extend the reach of limited clinical expertise. These are not substitutes for a functioning mental health system, but in places where that system barely exists, they offer a starting point.
