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Diagnostic microbiologic methods in the GEMS-1 case/control study
Sandra Panchalingam1, Martin Antonio, Anowar Hossain
1Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD, USA.
Insights
This study identified key bacterial, viral, and protozoal causes of severe childhood diarrhea in high-mortality regions. Findings support using these cost-effective diagnostic methods in developing countries.
Area of Science:
- Global Health
- Infectious Diseases
- Pediatrics
Background:
- Moderate-to-severe diarrhea remains a leading cause of mortality in children under five in sub-Saharan Africa and South Asia.
- Understanding the specific etiologies is crucial for developing targeted interventions and improving child survival rates.
Purpose of the Study:
- To comprehensively investigate the bacterial, viral, and protozoal causes of moderate-to-severe diarrhea in young children in high-mortality regions.
- To evaluate the utility of a standardized, cost-effective diagnostic assay portfolio for enteric pathogen detection in resource-limited settings.
Main Methods:
- A multi-site, case/control study involving children under five years old across seven locations.
- Utilized a uniform set of microbiological assays, including conventional methods for bacterial pathogens, multiplex PCR for diarrheagenic Escherichia coli, immunoassays for common viruses and protozoa, and a novel multiplex assay for norovirus, astrovirus, and sapovirus.
Main Results:
- Identified a spectrum of bacterial, viral, and protozoal pathogens contributing to severe diarrhea.
- Demonstrated the feasibility and effectiveness of applying a balanced portfolio of diagnostic assays at the study sites.
Conclusions:
- The diagnostic assay portfolio used in the GEMS study offers a robust and cost-effective approach for enteric pathogen detection.
- These methods can be broadly implemented in developing countries to aid in understanding and managing childhood diarrhea.
Abstract:
To understand the etiology of moderate-to-severe diarrhea among children in high mortality areas of sub-Saharan Africa and South Asia, we performed a comprehensive case/control study of children aged <5 years at 7 sites. Each site employed an identical case/control study design and each utilized a uniform comprehensive set of microbiological assays to identify the likely bacterial, viral and protozoal etiologies. The selected assays effected a balanced consideration of cost, robustness and performance, and all assays were performed at the study sites. Identification of bacterial pathogens employed streamlined conventional bacteriologic biochemical and serological algorithms. Diarrheagenic Escherichia coli were identified by application of a multiplex polymerase chain reaction assay for enterotoxigenic, enteroaggregative, and enteropathogenic E. coli. Rotavirus, adenovirus, Entamoeba histolytica, Giardia enterica, and Cryptosporidium species were detected by commercially available enzyme immunoassays on stool samples. Samples positive for adenovirus were further evaluated for adenovirus serotypes 40 and 41. We developed a novel multiplex assay to detect norovirus (types 1 and 2), astrovirus, and sapovirus. The portfolio of diagnostic assays used in the GEMS study can be broadly applied in developing countries seeking robust cost-effective methods for enteric pathogen detection.
