Detection of circulating antigens in patients with active Schistosoma haematobium infection.

Abstract

An antigen-capture ELISA using monoclonal antibody (MAb) 128C3/3/21 was used to detect circulating parasite-derived antigens in the sera of patients actively infected with Schistosoma haematobium (31 males and four females, 5-25 years of age). The assay had a sensitivity of 100% (35 of 35 patients with antigen levels Ͼ 80 ng/ml) and a specificity Ͼ 99%. We used this ELISA to monitor antigenemia before treatment and one, three, and six months after treatment with a single oral dose of praziquantel (PZQ) (60 mg/kg in 20 patients or 40 mg/kg in 15 patients) and compared our findings with those indicated by other measures of disease progression. Circulating antigen levels decreased drastically after PZQ treatment (P Ͻ 0.001), with a significantly higher decrease occurring after treatment with 60 mg/kg than with 40 mg/kg. Although the mean antigen level was still significantly reduced (P Ͻ 0.001) at six months after treatment, 16 patients remained antigen-positive after six months, and nine had increased levels of antigenemia, reflecting reinfection in six patients and persistence of infection in another. We observed a correlation (r ϭ 0.6, P Ͻ 0.01) between the level of circulating antigen and the intensity of infection as measured by egg count. We also found a direct relationship (P Ͻ 0.001) between antigen level and the severity of the disease as monitored by ultrasonography. We conclude that our ELISA may be a useful adjunct to other methods, such as ultrasonography, for monitoring the course of S. haematobium infection and treatment.

A monoclonal antibody against Schistosoma haematobium soluble egg antigen: efficacy for diagnosis and monitoring of cure of S. haematobium infection

“…At 12 weeks following praziquantel treatment, 87% of the serum samples (80/92) and 81.5% of the urine specimens (75/ 92) from S. haematobium-infected patients turned negative. A reduction in CSA levels following speci®c chemotherapy has also been reported by other investigators (De Jonge et al 1988, 1989aShaker et al 1992;Van Leishout et al 1991El-Morshedy et al 1996;Hassan et al 1998). The pro®le of CSA in urine following praziquantel treatment shows a parallel, albeit delayed, decline relative to that detected in serum.…”

“…However, the reports on CSA assays in S. haematobium infection have been very limited, and the positivity rate has been reported to be 100% in sera (Hassan et al 1998) and 90% (Nibbeling et al 1998) and 98% in urine (Bosompem et al 1997.…”

Relationship between circulating antigen level and morbidity in Schistosoma mansoni-infected children evaluated by ultrasonography.

“…When this format was used to examine sera from Schistosoma haematobium-infected children, the assay sensitivity was 100% and the specificity was Ͼ 99%, with no evidence of cross-reactivity with other parasites. 2 In these S. haematobium-infected patients, a positive correlation was observed between the level of circulating antigen and the egg count (r ϭ 0.6, P Ͻ 0.01). The mean circulating schistosomal antigen level was significantly higher in those with progressive urinary bladder morbidity as evaluated by ultrasonography (P Ͻ 0.001).…”

“…We have previously developed 1 and refined 2 an assay to measure antigenemia in schistosomiasis, a parasitic disease that affects more than 200 million people worldwide. Our diagnostic approach used a monoclonal antibody designated 128C3/3/21 (kindly supplied by the late Dr. Mette Strand, Johns Hopkins University, Baltimore, MD) in an antigencapture ELISA to detect circulating schistosome antigen and monitor the efficacy of praziquantel therapy in children with parasitologically proven schistosomiasis mansoni.…”

Association of Schistosoma haematobium and Human Papillomavirus in Cervical Cancer

“…In addition, immunodiagnosis for schistosomiasis by enzyme-linked immunosorbent assay (ELISA) based on the detection of antigen circulating in the serum and/or urine has been developed. 1,13,14 However, Brown 15 noted that the patients excreting Schistosoma ova in urine elicited positive ELISA titers, whereas patients who were previously positive but no longer passing viable eggs were negative for ELISA. This shows that ELISA is useful for the detection of active infection only.…”