Detection of antibodies to Schistosoma species
This assay can be used as a screening test for detection of antibodies to Schistosoma species.
Positive results should be interpreted alongside clinical findings and suitable exposure history.
A single negative result should not be used to rule-out Schistosoma infection.
False-positive results may occur in individuals with other helminth infections.
Enzyme Immunoassay (EIA)
Schistosomiasis
Bilharzia
Bilharziasis
Katayama fever
Serum
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into plastic vial.
If not ordering electronically, complete, print, and send Infectious Disease Serology Test Request (T916) with the specimen.
0.5 mL
Gross hemolysis | Reject |
Gross lipemia | Reject |
Heat inactivated | Reject |
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Serum | Refrigerated (preferred) | 30 days | |
Frozen | 30 days |
Detection of antibodies to Schistosoma species
Schistosoma species (class Trematoda) are flukes, characterized by their flat, leaf-like morphology as adults and use of gastropod mollusks (eg, snails) as an intermediate host. The schistosomes are also referred to as the "blood flukes" of which there are 5 species known to infect humans: Schistosoma mansoni, Schistosoma japonicum, Schistosoma haematobium, Schistosoma mekongi, and Schistosoma intercalatum. Among these S mansoni, S japonicum and S haematobium are most common.
These species have a defined geographic distribution, with S mansoni occurring throughout sub-Saharan Africa, the Middle East, and islands in the Caribbean; S haematobium found in much of the African continent and the Middle East; and S japonicum localized to China, Indonesia, and the Philippines.
Humans are definitive hosts for all Schistosoma species except for S japonicum, and infection begins with skin penetration of cercariae in contaminated water sources. The cercariae shed their bifurcated tails, becoming schistosomulae and migrate through the vascular system to the lungs, heart, and the portal venous system in the liver. There they mature to adults, pair off and migrate to the mesenteric venules of the bowel and rectum (S mansoni, S japonicum) or venus plexus of the bladder (S haematobium). Females will shed eggs, which are moved progressively towards the lumen of the intestine (S mansoni, S japonicum) and bladder (S haematobium) and are eliminated in the feces or urine, respectively. These eggs will hatch under ideal conditions, releasing miracidia, which penetrate specific snail (mollusk) intermediate hosts and develop into cercariae, continuing the life cycle.
While many infections are asymptomatic, acute schistosomiasis (Katayama fever), due to S mansoni or S japonicum, may occur weeks after initial infection. Symptoms include fever, cough, abdominal pain, diarrhea, hepatosplenomegaly, and eosinophilia. Central nervous system infection is uncommon; however, cerebral granulomatous disease may be caused by migration of Schistosoma eggs into the brain or spinal cord. Cystitis and ureteritis with hematuria are associated with S haematobium infection and can progress to bladder cancer.
Diagnosis of schistosomiasis can be made by detection of eggs in fecal or urine samples as appropriate for each species. Antibody detection can be useful for patients who reside in nonendemic areas but have recently traveled to regions where Schistosoma species are found and in whom eggs cannot be identified in fecal or urine examinations.
Negative
Negative: No IgG antibodies to Schistosoma species detected.
Equivocal: Recommend follow-up testing in 10 to 14 days if clinically indicated.
Positive: IgG antibody to Schistosoma species detected. Differentiation between Schistosoma species is not possible by this assay. Serologic cross-reactivity may occur in individuals with other helminth infections, including Echinococcus or Taenia species.
This assay is designed to specifically detect IgG-class antibodies to Schistosoma mansoni, which are likely cross-reactive to other Schistosoma species.
Sensitivity for detection of antibodies to each of the Schistosoma species has not been evaluated for this assay.
Patients may remain seropositive by this assay following appropriate treatment and clearance of the infection.
Positive results should be confirmed with other laboratory findings (eg, ova and parasite examination), clinical symptoms, and suitable exposure history.
The Mayo Clinic Infectious Disease Serology laboratory evaluated the accuracy of the NovaTec Schistosoma mansoni IgG enzyme-linked immunosorbent assay (ELISA) (as performed in our laboratory) using 64 serum samples that were previously tested by a fluorescent microsphere immunoassay at Focus Diagnostics. A comparison of the results is shown in Table 1.
Table 1. Accuracy of the NovaTec Schistosoma IgG assay compared to the Focus (Quest) Diagnostics assay
n = 64 | Focus (Quest) Diagnostics FMI | ||
Positive | Negative | ||
NovaTec ELISA | Positive | 31 | 1 |
Negative | 1 | 20 | |
Equivocal | 5 | 6 |
Positive agreement (95% CI): 83.8% (68.5-92.6%)
Negative agreement (95% CI): 96.3% (80.2-100%)
Overall agreement (95% CI): 89.1% (82.6-97%)
The Mayo Clinic Infectious Disease Serology laboratory also evaluated the analytic specificity of the NovaTec S mansoni IgG ELISA using 36 serum samples positive for antibodies to other helminth and protozoa. The results are shown in Table 2 below.
Table 2. Analytical specificity studies
Specimen | No. of specimens tested | No. of sera positive or equivocal by the S mansoni IgG ELISA |
Entamoeba histolytica IgG Ab | 6 | 0 |
Echinococcus species IgG Ab | 6 | 3 |
Strongyloides ratti IgG Ab | 6 | 2 |
Taenia solium IgG Ab | 6 | 2 |
Trichinella spiralis IgG Ab | 6 | 3 |
Trypanosoma cruzi IgG Ab | 6 | 1 |
The reference range for the NovaTec S mansoni IgG ELISA was established by testing serum from 50 normal donors; 47/50 (94%) of healthy individuals were negative by this ELISA.
1. Weerakoon KG, Gobert GN, Cai P, McManus DP. Advances in the diagnosis of human schistosomiasis. Clin Microbiol Rev. 2015;28(4):939-967
2. McManus DP, Dunne DW, Sacko M, Utzinger J, Vennervald BJ, Zhou XN. Schistosomiasis. Nat Rev Dis Primers. 2018;4(1):13
The qualitative immunoenzymatic determination of IgG-class antibodies against Schistosoma mansoni is based on the enzyme-linked immunosorbent assay (ELISA) technique.
Microtiter strip wells are precoated with Schistosoma mansoni antigens to bind corresponding antibodies of the specimen. After washing the wells to remove all unbound sample material, horseradish peroxidase-labelled protein A conjugate is added. This conjugate binds to antigen-antibody complexes. The immune complex formed by the bound conjugate is visualized by adding tetramethylbenzidine substrate, which gives a blue reaction product.
The intensity of this product is proportional to the amount of Schistosoma-specific IgG antibodies in the specimen. Sulfuric acid is added to stop the reaction. This produces a yellow endpoint color. Absorbance at 450 nm is read using an ELISA microwell plate reader.(Package insert: NovaLisa Schistosoma mansoni, Gold Standard Diagnostics; V SCHG0410engl,dt,fr,it,es18082009-JH Rev 01)
Tuesday, Thursday
This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.
86682
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
BILHA | Schistosoma Ab, IgG, S | 33317-9 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
BILHA | Schistosoma Ab, IgG, S | 33317-9 |