Diarrheal diseases remain a leading killer for children under 5, adults 70+

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A new global study reports a 60% drop in global mortality from diarrheal diseases, but children and the elderly still have the highest death rates, particularly in sub-Saharan Africa and South Asia. That’s according to the latest and most comprehensive study from the Global Burden of Disease (GBD) conducted by the Institute for Health Metrics and Evaluation (IHME) and published today in The Lancet Infectious Diseases journal.

Shigella_stool

Source: Centers for Disease Control and Prevention Publich Health Image Library

This photomicrograph revealed stool exudates in a patient with shigellosis, which is also known as “Shigella dysentery”, or “Bacterial dysentery”. Usually, those who are infected with Shigella develop diarrhea, which is often bloody, fever, and stomach cramps starting a day or two after they are exposed to the bacterium.

In 2021, diarrheal diseases caused 1.2 million deaths worldwide, which is a substantial drop from 2.9 million deaths recorded in 1990. The largest decrease was among children under 5 years with a 79% decline, but that age group still had the highest mortality rate among all ages, followed by those 70 years and older, making it a leading cause of death across all ages.

Regional disparities in diarrheal disease deaths remain stark. Regions with high-income countries see less than one death per 100,000 population in children under 5. In sub-Saharan Africa, more than 150 deaths per 100,000 population were in children under 5, which is the highest mortality rate for children in that age group when compared to all other global regions. South Asia had the highest mortality rates among those aged 70 years and older with 476 deaths per 100,000. Diarrheal mortality rates declined substantially across age groups in most super-regions.

Overall burden

Researchers analyzed the overall burden of diarrheal diseases by measuring disability-adjusted life years, or DALYs. That’s the sum of the number of years of life lost and the number of years lived with disability. DALYs declined from 186 million in 1990 to 59 million in 2021, but 31 million of those 2021 DALYs were in children younger than 5 years. Major risk factors for diarrheal DALYs include poor neonatal conditions such as low birthweight and preterm birth, child growth failure, unsafe water, and poor sanitation.

The decline in diarrheal mortality and morbidity suggests health interventions are working. They include oral rehydration therapy, enhanced water, sanitation, and hygiene infrastructure, and global immunization efforts against rotavirus. Preventive measures against key risk factors and pathogens could further reduce the global burden; according to researchers’ estimates, if leading risk factors were eliminated around the world, DALYs could be reduced to less than 5 million in 2021.

Helping decision-makers

“The new granular-level analysis by our study can further help decision-makers better target and prioritize the evidence-based strategies to fight diarrheal diseases,” said Dr. Hmwe Hmwe Kyu, study author and associate professor at IHME. “In spite of the encouraging progress made combating diarrheal mortality, a multipronged approach is required to simultaneously tackle live-saving solutions while also prioritizing preventive interventions to alleviate burdens on health systems.”

WHO-recommended rotavirus vaccines, now administered in over 100 countries, have led to substantial reductions in hospitalizations and deaths from diarrhea. With more vaccines being added to WHO’s Expanded Programme on Immunization, combining them could reduce manufacturing costs and make scheduling easier.

“In addition to increasing immunizations globally, we need to expand vaccine development to target specific pathogens that cause diarrheal diseases and consider combining vaccines to create a broader protection. This approach would be efficient and cost-effective for regions that are hit hardest by this global health crisis,” said Dr. Heidi Soeters, epidemiologist with WHO’s Department of Immunization, Vaccines and Biologicals.

Pathogen-specific data

For the first time, this research incorporates pathogen-specific data from WHO’s Global Pediatric Diarrhea Surveillance network from many high-burden countries.

The GBD is the most comprehensive assessment of health, which includes granular estimates of burden across all age groups, sexes, and locations, as well as risk factors for 204 countries and territories from 1990 to 2021. More data on the burden of diarrheal diseases are available via IHME’s visualization tools:

GBD Compare
GBD Results
GBD Results by pathogen and year