Methods for the detection of Cryptosporidium and Giardia: From microscopy to nucleic acid based tools in clinical and environmental regimes.

The detection and characterization of genotypes and sub genotypes of Cryptosporidium and Giardia is essential for their enumeration, surveillance, prevention, and control. Different diagnostic methods are available for the analysis of Cryptosporidium and Giardia including conventional phenotypic tools that face major limitations in the specific diagnosis of these protozoan parasites. The substantial advancement in the development of genetic signature based molecular tools for the quantification, diagnosis and genetic variation analysis has increased the understanding of the epidemiology and preventive measures of related infections. The conventional methods such as microscopy, antibody and enzyme based approaches, offer better detection results when combined with advanced molecular methods. Gene based approaches increase the precision of identification, for example, many signatures detected in environmental matrices represent species/genotype that are not infectious to humans. This review summarizes the available methods and the advantages and limitations of advance detection techniques like nucleic acid-based approaches for the detection of viable oocysts and cysts of Cryptosporidium and Giardia along with the conventional and widely accepted detection techniques like microscopy, antibody and enzyme based ones. This technical article also encourages the wide application of molecular methods in genetic characterization of distinct species of Cryptosporidium and Giardia, to adopt necessary preventive measures with reliable identification and mapping the source of contamination.