Entamoeba histolytica, Giardia intestinalis, and Cryptosporidium spp. are not only three of the most important and common diarrhea-causing parasitic protozoa, but they often have similar clinical presentations. Microscopic diagnosis of these parasites is neither sensitive nor specific. Recently, more specific and sensitive alternative molecular methods (polymerase chain reaction [PCR] and antigen detection tests) have been introduced for all three of these parasitic infections. The use of these molecular diagnostic tests in routine diagnostic laboratories is still limited. In this study, we developed a multiplex real-time PCR assay for the simultaneous detection of E. histolytica, G. intestinalis, and Cryptosporidium spp. in one reaction using species-specific probes. This assay was evaluated using clinical specimens and was found to be quite sensitive and specific. The reagents used in this multiplex PCR assay can also be used for detection of these parasites individually. The use of this real-time PCR multiplex assay in developing countries at present will have limited scope for routine diagnosis because the cost will be high for a single test, although in the developed world, the test could see immediate application.
