Development of diffractive optics technology-based immunoassay protocol and its application in the detection of Entamoeba histolytica infections.

Amebiasis due to infection with Entamoeba histolytica is a problematic parasitic disease in many countries. By means of a novel technology developed by Axela Biosensors, Inc., the dotLab™ system, a rapid immunoassay was developed to detect at least 5.45 cells/mL of E. histolytica, the causative agent of amebiasis, in spiked stool samples in 66 min. Regeneration of the dotLab™ sensor using 0.1 M glycine (pH 2.5) solution was established, enabling the assessment of multiple stool samples (up to 8 X) using a single sensor. This developed assay was applied to assess the health status of a community in relation to E. histolytica infections of relocated families in San Isidro, Rodriguez, Rizal, Philippines. The community was found to be 15.6% and 26.1% positive for E. histolytica using real-time polymerase chain reaction (real-time PCR) and dotLab™ methods, respectively. Compared to real-time PCR, the dotLab™ method is 94.74% sensitive and 74.79% specific. The agreement of the two methods was tested using Kappa coefficient test and it showed that dotLab™ is a reliable alternative to real-time PCR. The optimized dotLab™ assay did not cross-react with stool samples containing Escherichia coli, Blastocystis sp., Cryptosporidium sp. and Giardia intestinalis. The community had 17 X to 24 X higher infection rate than previous reports in the Philippines. Sex, age, and duration of settlement in the relocation area were not related to the rate of infection. This increase may be due to improper hygiene and sanitation in the community.