Study reveals major global decline in childhood diarrhea, yet regional inequalities persist

Researchers at Weill Cornell Medicine-Qatar (WCM-Q) have published a landmark global study in eBioMedicine, part of The Lancet Discovery Science, offering critical new insights into childhood diarrhea, one of the world’s leading causes of child mortality.

The study was initiated through WCM-Q’s Specialized Biomedical Research Training Program, a one-year initiative that equips recent graduates with hands-on experience in scientific projects and strengthens their capacity for long-term research careers in Qatar. Within this program, Zahir Tag, the study’s first author, honed his research expertise and developed a broad range of tools and competencies. Building on this foundation, he was recruited as a full-time researcher in WCM-Q’s research department, where he now contributes to different projects in epidemiology and global health.

Diarrhea remains a persistent global health challenge and is the third leading cause of child mortality worldwide, accounting for an estimated 445,000 deaths annually among children under five. The burden falls disproportionately on low- and middle-income countries, where 90 percent of these deaths occur. Beyond its immediate toll, diarrhea also impairs child growth and cognitive development, exacerbates malnutrition, and places a strain on families, healthcare systems, and economies.

Through a global analysis of 593 nationally representative population-based surveys from 129 countries conducted between 1985 and 2024, the study found that childhood diarrhea prevalence has fallen by more than half over the past four decades—from 22.3 percent in the 1980s to 10.9 percent in recent years—declining at an average rate of 1 percent per year. Moreover, prevalence declined across all major regions of the world, with only one region showing no reduction.

This remarkable progress reflects the combined impact of public health interventions, including rotavirus vaccination, oral rehydration therapy, breastfeeding promotion, and vitamin A supplementation, alongside broader improvements in socioeconomic conditions across many countries.

However, the study also revealed stark regional inequalities. The African Region carried the greatest burden, with the highest prevalence, while the European Region reported both the lowest prevalence and the steepest declines. In contrast, the Eastern Mediterranean Region stands out as an anomaly in this global success story: it continues to face a high burden of childhood diarrhea, with no measurable decline over the past four decades.

By examining the determinants of childhood diarrhea in a global context, the researchers developed a new Socioeconomic and Child Nutrition Index to track progress associated with lower prevalence. The index showed that countries with higher levels of maternal education, better child nutrition, and greater access to safe water and sanitation consistently reported lower rates of diarrhea—underscoring the condition not only as a health issue but also as a marker of broader socioeconomic development.

“Our findings tell a global success story. Millions of children are healthier today than they were four decades ago. But the persistence of high diarrhea prevalence in disadvantaged regions shows that progress has been uneven,” said Zahir Tag, first author of the study and research specialist at the Infectious Disease Epidemiology Group (IDEG) at WCM-Q. “To end preventable child deaths, we need not only proven health measures but also sustained investments in clean water, sanitation, education, and food security, as well as stronger responses to conflict-related emergencies that continue to disproportionately affect our region.”

Professor Laith Abu-Raddad, senior author of the study and professor of population health sciences at IDEG, concluded: “Childhood diarrhea is both a health challenge and a marker of inequality. Where societies advance, it recedes; where systems falter or are disrupted by conflict, it continues to claim young lives. It is a public health issue as much as a development challenge. The fight to end diarrhea is far from over.”

The study, titled Global childhood diarrhoea prevalence and its determinants: a systematic meta-analytic assessment, 1985–2024, was made possible through funding from the Specialized Biomedical Research Training Program and the Biostatistics, Epidemiology, and Biomathematics Research Core, all at Weill Cornell Medicine-Qatar.