Monday, May 13, 2013
A new international study published in The Lancet provides the clearest picture yet of the impact and most common causes of diarrheal diseases, the second leading killer of young children globally, after pneumonia. The Global Enteric Multicenter Study (GEMS) is the largest study ever conducted on diarrheal diseases in developing countries, enrolling more than 20,000 children from seven sites across Asia and Africa.
GEMS, coordinated by the University of Maryland School of Medicine’s Center for Vaccine Development, confirmed rotavirus – for which a vaccine already exists – as the leading cause of diarrheal diseases among infants and identified other top causes for which additional research is urgently needed. GEMS found that approximately one in five children under the age of two suffer from moderate-to-severe diarrhea (MSD) each year, which increased children’s risk of death 8.5-fold and led to stunted growth over a two-month follow-up period.
“Until now, comprehensive data on the burden of diarrheal diseases in Asia and sub-Saharan Africa has been limited,” said Myron M. Levine, M.D., D.T.P.H., founding director of the Center for Vaccine Development, and GEMS Principal Investigator. “By filling critical gaps in knowledge, we hope GEMS will help countries across these two highest-burden regions focus their efforts to improve child health.”
Despite many causes, GEMS found that targeting just four pathogens could prevent the majority of MSD cases. Expanding access to vaccines for rotavirus, the leading cause of MSD among infants at every site, could save hundreds of thousands of lives. Likewise, GEMS data suggests that accelerating research on vaccines, treatments and diagnostics for the three other leading pathogens – Shigella, Cryptosporidium and ST-ETEC, a type of E. coli – could have a similar impact. Prior to GEMS, Cryptosporidium was not considered a major cause of diarrheal disease and as a result there is currently little research on this pathogen underway.
"The mortality rate from childhood diarrhea had never been well quantified," says the study's lead author, Karen L. Kotloff, M.D., Professor of Pediatrics and Medicine, Head of the Division of Infectious Disease and Tropical Pediatrics, and Associate Director of Clinical Studies at the Center for Vaccine Development at the University of Maryland School of Medicine. "We had a sense that this was happening, but it had never been measured. Because children living in poverty in these regions of the world are already fragile, episodes of diarrhea seem to have a very severe impact on their health and well-being. We hope that this new data will help us develop better strategies to fight this critical global health issue."
“The GEMS findings help set priorities for investments that could greatly reduce the burden of childhood diarrheal diseases,” said Dr. Thomas Brewer, deputy director of the Enteric & Diarrheal Diseases team at the Bill & Melinda Gates Foundation, which funded the study. “Vaccines and treatments available today can save thousands of children right now but targeted research to develop new tools to combat severe diarrhea could save many more lives in the future.”
The GEMS findings also suggest that longer-term monitoring and care of children with diarrheal diseases could reduce mortality and developmental delays. Children with MSD grew significantly less in height in the two months following the diarrheal episode when compared with control children without diarrhea, and were 8.5 times more likely to die over the course of the two-month follow-up period. Notably, 61 percent of deaths occurred more than a week after the initial diarrheal episode, with 56 percent of deaths happening after families had returned home from a healthcare facility.
“GEMS strongly indicates that follow-up care after the initial diarrheal episode is critical to protect the health and wellbeing of children,” said Professor George Griffin, Senior Co-Chair of the GEMS International Strategic Advisory Committee and Professor at St. George’s, University of London. “By focusing only on the acute diarrhea that brings children to hospitals, we overlook a significant portion of diarrheal diseases’ burden.”
Expanding access to existing interventions that protect against or treat all diarrheal diseases, including oral rehydration solutions, zinc supplements, clean water and sanitation, can save lives and improve the health of children immediately.
“GEMS is a landmark study for the child health community,” said Professor Fred Binka, Co-Chair of the GEMS International Strategic Advisory Committee and Vice-Chancellor at the University of Health and Allied Sciences, Ghana. “By using consistent methods across countries, GEMS sites generated data that can guide evidence-based decision making at both the local and global levels.”
Release of the GEMS findings follows last month’s announcement by the World Health Organization and UNICEF of the first-ever Integrated Global Action Plan for the Prevention and Control of Pneumonia and Diarrhea (GAPPD). The GEMS findings add to the scientific evidence cited in the GAPPD strategy for effectively controlling pneumonia and diarrhea, which together are the two leading causes of death among young children globally.
GEMS, coordinated by the University of Maryland School of Medicine’s Center for Vaccine Development, was a case-control study conducted at seven diverse, high-burden sites in Asia and Africa: the Gambia, Kenya, Mali, Mozambique, Bangladesh, India and Pakistan. The study enrolled 22,568 children under five years of age, a sample size that is large enough to provide comprehensive data on the causes, incidence and impact of the range of diarrheal diseases affecting children around the world.
GEMS established a network of well-equipped laboratories in the study countries that can be used to accelerate future research on diarrhea and other child health priorities. Investigators have provided open access to their data, which can provide baselines for further studies. Supplemental materials on GEMS methods and sub-studies can be found in Clinical Infectious Diseases (volume 55, supplement 4, and December 2012) and the American Journal of Tropical Medicine and Hygiene. Additional analyses of GEMS data are ongoing.
For further information, please visit http://medschool.umaryland.edu/GEMS/.
About the Center for Vaccine Development
The Center for Vaccine Development (CVD) at the University of Maryland School of Medicine in Baltimore has earned an international reputation as an academic vaccine development enterprise. Since its inception in 1974, the Center is known for creating and testing vaccines against cholera, typhoid fever, paratyphoid fever, non-typhoidal Salmonella disease, shigellosis (bacillary dysentery), Escherichia coli diarrhea, malaria, and other infectious diseases, including influenza. Its global staff includes molecular biologists, microbiologists, immunologists, internists, pediatricians, epidemiologists, malariologists, biostatisticians and informaticians. The CVD is engaged in the full range of vaccinology, from basic laboratory science research through vaccine development, early clinical evaluation, large-scale pre-licensure field studies and post-licensure assessments. In addition to its research and outpatient facilities in Baltimore, Maryland, the CVD has facilities to conduct clinical studies in Mali, West Africa, Malawi, Southern Africa and Santiago, Chile and undertakes time-limited field studies in many other countries in Africa, Asia and Latin America.