New Rapid Diagnostic Tests for Amebiasis

DESCRIPTION (provided by applicant): Our goal is to produce point-of-care diagnostic tests for amebiasis. Entamoeba histolytica is a protozoan parasite and the causative agent of amebiasis in humans. Intestinal amebiasis causes debilitating diarrhea and dysentery, while extraintestinal amebiasis occurs when the parasite migrates from the intestinal tract to organs throughout the body, most commonly the liver. The NIAID Blue Ribbon Panel on Biodefense Agents BandC targeted E. histolytica as one of the three parasitic pathogens of highest priority for research because it is environmentally stable, infectious at a low dose, and is a significant cause of morbidity and mortality worldwide. E. histolytica cysts are predominantly acquired through ingestion of contaminated food and water, leading to 50 million cases of amebic colitis and amebic liver abscess annually, and an estimated 100,000 deaths occurring due to infection. Accurate diagnosis of infection by fecal microscopy, antigen testing, PCR, or IFA leads to successful treatment and full recovery. Several issues confound proper diagnosis, including the litany of other organisms that can cause similar intestinal symptoms, the presence of non-pathogenic Entamoeba spp. in the fecal specimen, and the lack of fecal positive results once amebic infections become invasive. E. histolytica must be specifically identified since non-pathogenic strains of Entamoeba spp. colonize the human intestine at 3-10 fold the rate of E. histolytica, making E. histolytica-specific diagnostics of particular value. Proper identification eliminates misdiagnosis of symptoms and treatment with unnecessary and possibly dangerous drugs. Further, a simple method of diagnosis must be made available to identify invasive amebiasis in the absence of positive fecal testing. This STTR Phase II application describes the GMP manufacture of two integrated rapid diagnostic tests used for the identification of intestinal and extraintestinal amebic infections in humans. Specific Aim #1 highlights production and FDA clearance of the E. HISTOLYTICA FECAL ANTIGEN QUIK CHEK test, which is designed to identify E. histolytica-specific antigen in fecal specimens from patients with amebic colitis, and in serum, whole blood, saliva and urine from patients with extraintestinal amebiasis. Specific Aim #2 highlights production and FDA clearance of the E. HISTOLYTICA SERUM ANTIBODY QUIK CHEK test, which is designed to detect anti-E. histolytica antibodies in serum samples of patients exposed to E. histolytica who are antigen negative. The tests will be manufactured at TechLab, Inc. using reagents developed through our partnership with the University of Virginia. The tests will be provided to UVA and our consortium sites in Bangladesh and Germany for clinical testing. Both sites have access to specimens and patients from areas where amebiasis is endemic. Further, this application will detail use of these two tests together in point-of-care environments in order to identify the most effective diagnostic strategy for identifying amebiasis in humans. PUBLIC HEALTH RELEVANCE: Entamoeba histolytica, a pathogenic parasite of the human intestine, liver and other organs, could be utilized as a bio-warfare agent spread through water supplies. It infects hundreds of millions of people worldwide and causes an estimated 100,000 deaths annually due to diarrhea, dysentery, and liver abscess. This project details the production of two highly sensitive and specific Point-of-Care diagnostic tests capable of identifying Entamoeba histolytica infections in humans, thus promoting effective treatment and identification of outbreaks.