Entamoeba histolytica IgG - ELISA

GWB-BE1540

Entamoeba histolytica is an anaerobe parasite forming cysts which have four small nuclei and measure 10-15 & mu; m in diameter. The cysts are sturdy and resist adverse environmental conditions. After ingestion by a susceptible host (invertebrates and vertebrates including humans) its wall is disrupted by the formation of a small opening through which an amoeba emerges. The amoeba divides serially through three cycles giving rise to eight uninucleate trophozoites from one cyst which are motile and measure 20-30 & mu; m in diameter. Some of the trophozoites then invade the tissues of the large intestine and may erode them so extensively that they gain entrance into the bloodstream. Thus amoebae can reach all parts of the body. Infection with Entamoeba histolytica has worldwide distribution. It is the causative agent of amoebiasis and amoebic dysentery and inhabits the lumen and mucosa of the large intestine predominantly the transverse colon and cecum. Extra intestinal amoebiasis can afflict any organ or tissue. The majority of infected individuals are free of symptoms; this high incidence of asymptomatic carriers complicates matters. Those who are symptomatic experience a wide range of manifestations. Members of all age groups and both sexes are infected. The risk of infection increases with inadequate sanitary conditions. An increased prevalence of amoebiasis is found among people who have an increased risk of exposure in the agricultural occupations and in male homosexuals. Infection may be identified byMicroscopy: stool examination: iron haematoxylin method merthiolat iod formol concentration (MIFC)Serology: CF CIE ELISAPrinciples of the assay: The qualitative immunoenzymatic determination of antibodies against Entamoeba histolytica is based on the ELISA (Enzyme-linked Immunosorbent Assay) technique. Especially asymptomatic carriers and cases of a previous non-invasive amoebiasis may be identified. Microtiter strip wells are precoated with Entamoeba histolytica antigens to bind corresponding antibodies of the specimen. After washing the wells to remove all unbound sample material horseradish peroxidase (HRP) labelled Protein A Conjugate is added. This conjugate binds to the captured Entamoeba histolytica specific antibodies. The immune complex formed by the bound conjugate is visualized by adding Tetramethylbenzidine (TMB) substrate which gives a blue reaction product. The intensity of this product is proportional to the amount of Entamoeba histolytica specific antibodies in the specimen. Sulphuric acid is added to stop the reaction. This produces a yellow endpoint colour. Absorbance at 450 nm is read using an ELISA microwell plate reader. Storage and Stability: The reagents are stable up to the expiry date stated on the label when stored at 2. . . 8 & deg; C. Limitations of the Test: Bacterial contamination or repeated freeze-thaw cycles of the specimen may affect the absorbance values. Diagnosis of an infectious disease should not be established on the basis of a single test result. A precise diagnosis should take into consideration clinical history symptomatology as well as serological data. In immunocompromised patients and newborns serological data only have restricted value. References Patterson M. et al. Serologic Testing of Amebiasis. Gastroenterology. 78:136 1980Healy G. Laboratory Diagnosis of Amebiasis. Bull NY Acad Med. 47:478 1971Healy G. Immunologic Tools in the Diagnosis of Amebiasis: Epidemiology in the united states. Rev Infect Diseases. Vol. 8 2:228 1986Walsh J. Problems in Recognition and Diagnosis of Amebiasis: Estimation of the Global Magnitude of Morbidity and Mortality. Rev Infect Diseases. Vol. 8 2:228 1986