Diarrhea is an important cause of morbidity and mortality, worldwide. Giardia intestinalis, Cryptosporidium spp., and Entamoeba histolytica are the most common diarrhea-causing parasitic protozoa. Diagnosis of these parasites is usually performed by microscopy. However, microscopy lacks sensitivity and specificity. Replacing microscopy with more sensitive and specific nucleic acid based methods is hampered by the higher costs, in particular in developing countries. Multiplexing the detection of more than one parasite in a single test by real-time polymerase chain reaction (PCR) has been found to be very effective and would decrease the cost of the test. In the present study, stool samples collected from 396 Egyptian patients complaining of diarrhea along with 202 faecal samples from healthy controls were examined microscopically by direct smear method and after concentration using formol-ethyl acetate. Frozen portions of the same samples were tested by multiplex real-time for simultaneous detection of E. histolytica, G. intestinalis, and Cryptosporidium spp. The results indicate that among diarrheal patients in Egypt G. intestinalis is the most common protozoan parasite, with prevalence rates of 30.5 and 37.1 %, depending on the method used (microscopy vs. multiplex real-time PCR). Cryptosporidium spp. was detected in 1 % of the diarrheal patients by microscopy and in 3 % by real-time PCR. While E. histolytica/dispar was detected in 10.8 % by microscopy, less than one fifth of them (2 %) were found true positive for Entamoeba dispar by real-time PCR. E. histolytica DNA was not detected in any of the diarrheal patients. In comparison with multiplex real-time PCR, microscopy exhibited many false positive and negative cases with the three parasites giving sensitivities and specificities of 100 and 91 % for E. histolytica/dispar, 57.8 and 85.5 % for G. intestinalis, and 33.3 and 100 % for Cryptosporidium spp.

The diagnostic efficacy of Fasciola gigantica adult worm vomit (AWV) preparation in diagnosis of human fasciolosis was evaluated using conventional enzyme-linked immunosorbent assay (ELISA) and Falcon assay screening test (FAST)-ELISA in comparison with F. gigantica adult total soluble extract (TSE). Sera of fasciolosis patients, patients with other parasitic diseases (hydatid disease, schistosomiasis, toxoplasmosis, and amebiasis), and sera of healthy individuals were enrolled in this study. The results showed that the sensitivity of both conventional ELISA and FAST-ELISA was improved from 95 % using TSE to 100 % when using AWV. The specificity of conventional ELISA was 93.3 % using TSE and increased to 96.7 % using AWV. The specificity of FAST-ELISA using TSE was 96.7 % and became 100 % AWV antigen. The diagnostic accuracy of conventional ELISA was 94 % using TSE and increased to 98 % using AWV. The diagnostic accuracy of FAST-ELISA was 96 % using TSE and increased to 100 % using AWV. It is concluded that both TSE and AWV antigenic preparations are efficient for use in the serodiagnosis of human fasciolosis.