IgG Western Blot for Confirmatory Diagnosis of Equivocal Cases of Toxoplasmosis by EIA-IgG and Fluorescent Antibody Test

The performance values of available techniques used in serodiagnosis of toxoplasmosis are satisfactory but they raise problems of equivocal and discordant results for very low IgG titers. Recently marketed, LDBio-Toxo II IgG Western blot (IB) showed an excellent correlation with the dye test. We estimated the proportion of equivocal and discordant results between the enzyme immunoassay Platelia Toxo IgG (EIA-IgG) and fluorescent antibody test (FAT) and assessed the usefulness of the IB as a confirmatory test. Out of 2,136 sera collected from pregnant women, 1,644 (77.0%) tested unequivocally positive and 407 (19.0%) were negative in both EIA-IgG and FAT. The remaining 85 (4%) sera showed equivocal or discordant results. Among them, 73 (85.9%) were positive and 12 (14.1%) were negative in IB. Forty-one (89.1%) equivocal sera in EIA-IgG and 46 (86.8%) equivocal sera in FAT were positive in IB. Reducing the cut-off values of both screening techniques improved significantly their sensitivity in detecting very low IgG titers at the expense of their specificity. In conclusion, equivocal results in routine-used techniques and their discordance in determination of the immune status in pregnancy women were not uncommon. IB test appeard to be highly useful in these situations as a confirmatory technique.

[Acanthamoeba keratitis: report of 3 cases diagnosed in central Tunisia]

Amoeba of the genus Acanthamoeba are ubiquitous free-living protozoa encountered in water and soil. They frequently cause sight-threatening keratitis. Report of the three first cases diagnosed at the laboratory of Parasitology of Sousse Hospital. [Tunisia]. Our study concerned three lens-wearing female patients. aged 17, 20 and 29 years respectively. The patients originate from central Tunisia and presented with unilateral [2 cases] or bilateral [one case] keratitis. Diagnosis was made by demonstrating Acanthamoeba trophozoites and/or cysts on direct examination and/or culture [in agar-Escherichia coli medium] of contact lenses and/or lenses' solution. Direct examination of corneal swabs was negative in three cases but culture was positive in one. The three patients were treated with hexamidine and neomycine eye-drops for three months. Treatment led to scarring of lesions with however sequellar opacities that was minor to moderate in two cases and consisted of a central leucoma with a poor visual outcome in the last case. The need for systematic research of amoeba in lenses wearing patients with keratitis is emphasized