Amoebiasis

The standard method to diagnose amoebiasis is detection and identification of Entamoeba histolytica in faeces, biopsies, or abscess material. However, cysts of the pathogenic E. histolytica and the apathogenic E. dispar are morphological indistinguishable. Over the last years various techniques including ELISA, IFL, and PCR have been developed to differentiate between the two amoebae species in faeces (Mirelman et al. 1997; Tachibana et al. 1997; Haque et al. 1998).

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Most of the serological methods available over the last decades have been used for antibody detection when amoebiasis, both intestinal and extra intestinal, has been suspected. The positive antibody response is in general a good predictor for Entamoeba infection in patients from non-endemic areas, but in endemic areas the healthy population is often seropositive (Hossain et al. 1983). Immunodiffusion is less sensitive compared to IFL and ELISA, but has a higher specificity and shows a close correlation with clinical disease in an area of low endemicity (Stamm et al. 1976).

The cysteine-rich immunodominant domain of the antigenic 170-kDa subunit of the galactose-V-acetylgalactosamine binding lectin expressed as a recombinant lectin seems to be able to replace the crude amoeba antigen for use in serological test showing a sensitivity and specificity over 90% (Zhang et al. 1992; Shenai et al. 1996).

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