A recent global analysis finds that global mortality from diarrheal diseases has decreased by 60%, yet children and the elderly continue to die at the highest rates, primarily in sub-Saharan Africa and South Asia.  The Institute for Health Metrics and Evaluation (IHME) published the most recent and comprehensive Global Burden of Disease (GBD) study in The Lancet Infectious Diseases.

Diarrhoeal diseases killed 1.2 million persons worldwide in 2021, a considerable decline from the 2.9 million deaths reported in 1990. The greatest drop occurred among children under the age of five, with a 79% decline, but that age group still had the highest mortality rate of all ages, followed by those aged 70 and up, making it a leading cause of death across all ages.

Diarrhoea mortality rates continue to vary significantly by region. In high-income countries, children under the age of five die at a rate of fewer than one in 100,000. Sub-Saharan Africa has the highest mortality rate for children under the age of five, with more than 150 deaths per 100,000 people, compared to all other global regions. South Asia had the highest mortality rate for those aged 70 and up, with 476 deaths per 100,000. Diarrhoeal mortality rates decreased dramatically across age groups in most superregions.

The researchers calculated disability-adjusted life years (DALYs) to determine the overall burden of diarrheal illnesses. That is the total number of years of life lost plus the number of years spent on disability. DALYs dropped from 186 million in 1990 to 59 million in 2021, with 31 million affecting children under the age of five. Poor neonatal conditions, such as low birthweight and early birth; child growth failure; contaminated water; and inadequate sanitation, all pose significant risks for diarrheal DALYs.

The decrease in diarrheal mortality and morbidity suggests that healthcare interventions are beneficial.  They include oral rehydration therapy, improved water, sanitation, and hygiene infrastructure, and global rotavirus vaccination efforts. Experts believe that eliminating key risk factors globally could cut DALYs to less than 5 million by 2021.

"The new granular-level analysis in our study can further help decision-makers target and prioritize evidence-based strategies to fight diarrheal diseases," said Dr. Hmwe Kyu, the paper's author and associate professor at IHME.  Despite positive progress in decreasing diarrheal mortality, we need a multifaceted approach that addresses life-saving measures while prioritizing preventive efforts to reduce the load on health systems.

Rotavirus vaccines recommended by the WHO, which are now accessible in more than 100 countries, have resulted in considerable reductions in hospitalizations and diarrhea-related deaths.  Combining new vaccines with WHO's Expanded Programme on Immunisation may save manufacturing costs and improve scheduling.

"In addition to increasing global immunisation rates, we must accelerate vaccine development to target specific organisms that cause diarrhoea and consider combining immunisations to provide broader protection. Dr. Heidi Soeters, an epidemiologist at WHO's Department of Immunisation, Vaccines, and Biologicals, stated that this technique would be efficient and cost-effective for the regions most hit by the global health crisis.

This is the first study to incorporate pathogen-specific data from WHO's Global Paediatric Diarrhoea Surveillance network, which includes several high-burden countries.