Deaths from infections that cause diarrhea and other intestinal illnesses have fallen sharply since 1990, according to a study published last week in The Lancet Infectious Diseases.

Using data from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2023, an international team of researchers examined mortality from enteric infectious diseases across 204 countries and territories from 1990 to 2023. The category included diarrheal disease, invasive nontyphoidal Salmonella (iNTS) infections, enteric fever (typhoid and paratyphoid), and other intestinal infectious diseases, which are typically transmitted through the fecal-oral route by contaminated food, water, or hands and can be highly contagious. 

Their analysis found that the number of global deaths from enteric infectious diseases fell from 3.69 million in 1990 to 1.27 million in 2023, and the global age-standardized mortality rate fell from 74.1 per 100,000 to 16.4. 

Rotavirus vaccine makes big impact

Diarrheal disease accounted for most of the deaths in 2023 (1.11 million), followed by enteric fever and iNTS infections. Rotavirus was the leading cause of diarrheal disease (16.3%), followed by norovirus (10.2%) and Shigella (9.3%). Asia (599,00) and sub-Saharan Africa (501,000) had the largest number of deaths from enteric infectious diseases in 2023. 

Researchers with the Institute for Health Metrics and Evaluation (IHME) at the University of Washington were among the dozens of scientists involved in the study, which was funded by the Gates Foundation. They say the reductions are the result of multiple overlapping preventive measures aimed at enteric infections, including increased access to rotavirus vaccines, which is up to 98% effective against severe illness in infants in high-income countries. 

“The leading pathogen driving diarrheal deaths among children across 1990-2023 was rotavirus, of which deaths were greatly reduced by global introduction of rotavirus vaccination in 2006,” Hmwe Hmwe Kyu, MBBS, MPH, PhD, an associate professor in department of health metrics sciences at UW School of Medicine and IHME, told CIDRAP News in an email. Other factors include increased access to oral rehydration salts, which quickly replenish fluids in people with diarrhea, and clean drinking water. 

The leading pathogen driving diarrheal deaths among children across 1990-2023 was rotavirus, of which deaths were greatly reduced by global introduction of rotavirus vaccination in 2006.

“While these are the main driving forces influencing the reduction in deaths due to enteric infectious diseases, there are other factors that contribute, such as improved access to zinc treatment and safer access to toilets,” Kyu said.

Children under 5 disproportionately affected

While mortality fell across all age-groups, young children saw significant reductions. Kyu noted that, in 1990, children under 5 years old made up roughly 53% of deaths from enteric infectious diseases. By 2023, that number had fallen to 30%. 

Still, an estimated 317,000 children under 5 died from diarrheal disease in 2023. More than 70% of those deaths where in sub-Saharan Africa. And more than a quarter of the countries failed to meet the global target for diarrheal disease deaths in children under 5 (fewer than 20 deaths per 100,000 population by 2025), the researchers found.

Kyu said higher rotavirus vaccine coverage could help further reduce childhood deaths from diarrhea. In the 63 countries that failed to meet the target, she said, rotavirus is consistently one of the higher causes of under-5 diarrhea deaths.

Progress under threat

Kyu and her colleagues also noted that reductions in global health financing, the changing geographic landscape of key enteric pathogens because of climate change, and a rise in drug-resistant bacteria—which limits the effectiveness of treatments for bacterial enteric infections—all pose a threat to that progress.

“The compilation of these challenges casts uncertainty over the sustainability and future direction of global enteric disease prevention and control efforts,” they wrote.

Kyu said it’s possible that deaths from enteric infectious disease could plateau in the coming years, or even increase, because of these factors. But she also pointed to some hopeful signs, including the rollout of rotavirus vaccination in countries like Vietnam, Iran, and Somalia, and recently announced World Bank funding for a program to improve access to clean water, sanitation, and hygiene in eastern and southern Africa.

“With these more encouraging developments, it is possible that deaths due to enteric infectious diseases will continue to decrease,” she said.