Schistosoma mansoni: Demonstration of two circulating antigens in infected hamsters

Abstract. While research on alternative diagnostic and morbidity markers for infection with Schistosoma haematobium has been going on for a long time, egg counts continue to be used as the gold standard, and infection intensity is thought to reflect the severity of the disease. However, this relationship is not always clear and fluctuation in egg output makes it difficult to classify prevalence correctly. The use of circulating adult worm antigen detection as an alternative diagnostic technique has been applied with varying success. However, this is a measure of worm burden and does not reflect the tissue egg load(s). In the present study we have used an assay that detects soluble egg antigen (SEA) in urine of S. haematobium-infected children, and we have evaluated the applicability of the assay as a diagnostic and morbidity indicator. To evaluate this assay, we have studied a group of 470 children from two schools (Tsunguni and Kibaokiche) in the Coast province of Kenya; 84.8% and 77% were egg-positive while the percentage positive as determined by the SEA-ELISA were 78.8% and 76.2% in Tsunguni and Kibaokiche, respectively. In both schools, SEA levels in urine of S. haematobium-infected children significantly correlated with egg counts (Pearson's r ϭ 0.73, P Ͻ 0.0001) and with hematuria (Spearman's r ϭ 0.65, P Ͻ 0.0001). In addition, urinary tract pathology as determined by ultrasound significantly correlated with the SEA levels in urine (Spearman's r ϭ 0.3, P Ͻ 0.001). The SEA-ELISA compared well with microhematuria within egg count classes and with egg counts within hematuria classes.Detection of Schistosoma haematobium ova in urine of infected individuals remains the leading method for the direct diagnosis of the disease, and the intensity of infection expressed as number of eggs per 10 ml of urine is thought to reflect the worm burden. However, a homogeneous distribution of S. haematobium ova in urine is difficult to achieve, 1 while day-to-day and circadian variation in egg excretion may lead to incorrect estimates in prevalence and intensity of infection. Additionally, the relationship between egg counts and pathology is not always clear. 2 The presence and intensity of microhematuria, proteinuria, and leukocyturia are semi-quantitative measures of S. haematobium infection, and these parameters were found to correlate with infection intensity. 3-5 However, variations dependent on geographic area, endemicity, cultural practices, age, sex, and even time of the day exist, limiting the application of hematuria as a diagnostic tool. 6-9 Ultrasound scanning of the urinary tract remains the gold standard for pathology. This technique has been applied in the field and correlates well with standard direct and indirect measurements of S. haematobium morbidity. 10,11 However, ultrasound equipment is expensive and requires trained physicians to handle the equipment and interpret the results, limiting its use under field conditions. These shortcomings have led to the search for alternative quantitative diagnostic meth...

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“…Schistosoma haematobium (Egyptian strain) SEA prepared as previously described 25 was used for ELISA standard curves.…”

Section: Methodsmentioning

confidence: 99%

Detection and quantification of soluble egg antigen in urine of Schistosoma haematobium-infected children from Kenya.

Kahama¹,

Nibbeling²,

Zeyl³

et al. 1998

The American Journal of Tropical Medicine and Hygiene

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“…Circulating polysaccharide proteoglycan antigens first detected in the sera of heavily infected experimental animals (29,98,142) and implicated in serum sickness-like symptoms in acutely infected persons (98)(99)(100)(101)(203)(204)(205)(206) are the major candidates for IC formation. These consist of GASP/CAA and circulating cathodic antigen (CCA), a positively charged, large sugar moiety-containing molecule; both of these originate from the gut epithelium of the worms (12).…”

Section: Introductionmentioning

confidence: 99%

Immunopathology of Schistosoma mansoni infection

1989

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Schistosomiasis mansoni is a chronic helminthic disease that affects about 100 million people in the tropics. The worms have a life span of 5 to 10 years, and they live in the mesenteric veins of the host. Lightly infected individuals are asymptomatic or manifest mild intestinal symptoms. Heavily infected individuals often develop severe morbidity with hepatosplenomegaly, sometimes with a fatal outcome. Morbidity is attributed to the strong humoral and T-cell-mediated host immune responses developed to a variety of parasite antigens and expressed as tissue inflammations. The immunopathology includes dermatitis, immune complex-mediated kidney disease, and, chiefly, T-cell-mediated granuloma formation and fibrosis around disseminated parasite eggs. This review describes the mechanisms of induction and expression of immunopathology in infected persons and experimental animals. Immunoregulatory mechanisms that modulate the enhanced immune responses and may ameliorate excessive morbidity are discussed.

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“…3,4,6,7,19 The intravascular location of schistosomes ensures that antigens excreted or secreted by worms and eggs directly enter the maternal vasculature. 14,26,37 These antigens may thus reach the placenta and the fetal vessels. 14,15,19,25,38 For the schistosome antigen CAA, it has already been shown in an animal model that it can be transferred to the offspring via the placenta.…”

Section: Discussionmentioning

confidence: 99%

Association of In Utero Sensitization to Schistosoma haematobium with Enhanced Cord Blood IgE and Increased Frequencies of CD5– B Cells in African Newborns

Seydel

Petelski²,

Dam³

et al. 2012

The American Society of Tropical Medicine and Hygiene

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Abstract. This study investigated in utero priming as a consequence of maternal parasitic infections. Cord blood plasma samples of 63 African newborns were assessed by enzyme-linked immunosorbent assay for their content of total and schistosome-specific or filaria-specific IgE and IgG4. The frequencies of lymphocyte phenotypes in cord blood were also determined by using flow cytometry, and were compared with those of European newborns. We found significantly increased schistosome soluble egg antigen (SEA)-specific IgE in cord plasma of those born to mothers with schistosome infections and correlations between fetal and maternal SEA-specific and filaria antigen-specific IgE. These data are evidence for in utero priming of the fetal immune system to maternal helminth infections. Furthermore, we show significantly enhanced percentages of CD5-B cells in African newborns cord blood compared with Europeans, which is consistent with earlier maturation of the African fetal immune system.

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Schistosoma mansoni: Demonstration of two circulating antigens in infected hamsters

Cited by 121 publications

References 9 publications

Detection and quantification of soluble egg antigen in urine of Schistosoma haematobium-infected children from Kenya.

Detection and quantification of soluble egg antigen in urine of Schistosoma haematobium-infected children from Kenya.

Immunopathology of Schistosoma mansoni infection

Association of In Utero Sensitization to Schistosoma haematobium with Enhanced Cord Blood IgE and Increased Frequencies of CD5– B Cells in African Newborns

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