Comparison of the circulating carbohydrate antigen and the anti-SWAP antibodies in patients with active schistosoma haematobium infection

ABSTRACT

Twenty five patients, with age ranged from 5-25 years [mean +/- SD 12.8 +/- 4.7] with active S. haematobium infection were investigated in the present study. They were subjected to complete clinical history, examination, abdominal ultrasonography and urine and stool examination. Nuclepore filtration method for quantitation of S - haematobium ova was performed. Immunological assays to study the levels of circulating carbohydrate antigen lusing monoclonal antibody 128 C3/3/21] and anti-SWAP [soluble adult worm antigen preparation] immunoglobulins IgG1, IgG4 and IgE were performed. The patients were re-evaluated again at 1, 3 and 6 months of receiving praziquantel therapy. It was found that all Patients had significantly high circulating carbohydrate antigen in their sera i.e. above the cut-off value. Also, there was a significant drop in the mean circulating antigen levels at 1, 3 and 6 months after praziquantel treatment. However, the levels of the circulating antigen did not reach to the cut-off value in, 12 patients 6 months after treatment; 5 of these patients had evidence of reinfection and/or persistence of infection. On the other hand, all the patients had positive ELISA reaction for IgGl and IgG4, while 5 patients had negative reaction for IgE through the different visits before and after treatment. The decrease in the mean levels of IgGl and IgG4 was statistically significant only after 6 months of treatment; but the mean levels of IgE showed significant drop at 3 and 6 months after treatment. These findings suggested that the detection of circulating carbohydrate antigen is more accurate in diagnosis of active infection, reinfection-and in evaluating the efficacy of treatment. We found a significant correlation between the circulating carbohydrate antigen levels and the anti-SWAP IgE during the active infection but no significant correlation was found between the antigen levels and IgGl and IgG4. This may be attributed to the fact that IgE antibodies to S- haematobium adult worm antigen increase with the parasite load. Further evaluation must be performed on a large number of patients with more prolonged period of follow-up