Molecular diagnosis of infectious diarrhea: focus on enteric protozoa

Abstract

Robust detection of enteric protozoa is a critical step toward determining the etiology of diarrhea. Widespread use of conventional microscopy, culturing and antigen detection in both industrial and developing countries is limited by relatively low sensitivity and specificity. Refinements of these conventional approaches that reduce turnaround time and instrumentation have yielded strong alternatives for clinical and research use. However, advances in molecular diagnostics for protozoal, bacterial, viral and helminth infections offer significant advantages in studies seeking to understand pathogenesis, transmission and long-term consequences of infectious diarrhea. Quantitation of enteropathogen burden and highly multiplexed platforms for molecular detection dramatically improve predictive power in emerging models of diarrheal etiology, while eliminating the expense of multiple tests.

Keywords::

• developing world
• diarrheal disease
• enteric protozoa
• molecular diagnostics
• nucleic acid amplification tests

Acknowledgements

The authors would like to thank Ann Therese Verkerke for her generous contribution of artwork to Figure 1.

Financial & competing interests disclosure

Preparation of this manuscript was supported by a Fulbright Student Research Grant to HV and NIH 5R01 AI043596 to WA Petri. WA Petri received licensing fees from TechLab Inc., a diagnostics company in Blacksburg, Virginia. He donates these fees in full to the American Society of Tropical Medicine and Hygiene. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Key issues

• Molecular detection and characterization of enteric protozoa is an important component of global efforts to study and decrease the burden of diarrhea associated morbidity and mortality.

• Conventional methods for detection of enteric protozoa have relatively low sensitivity and specificity compared to molecular detection methods.

• Genetic and pathogenic diversity among closely related species and subtypes typify enteric protozoa, making molecular methods with sequence specificity and resolution particularly attractive tools for their detection.

• Major enteric protozoa have been incorporated into highly multiplexed platforms that offer broad pathogen coverage in regions of diverse and variable enteropathogen endemicity.

• Quantification of pathogen load is critical for preventing misattribution of diarrheal episodes and adds statistical power to odds ratios by defining the clinical relevance of a specific pathogen burden.

Notes