National Health and Nutrition Examination Survey

2009-2010 Data Documentation, Codebook, and Frequencies

Toxoplasma Gondii Antibody - Serum (Surplus) (SSTOXO_F)

Data File: SSTOXO_F.xpt

First Published: August 2013

Last Revised: April 2022

Note: The NHANES Biospecimen Program processes were reevaluated in 2021 and 2022 to monitor quality control after a procedural error was identified. This error did not pose any risk of participant disclosure. Addressing this error resulted in the removal of some records from various stored biospecimen data files between 1999 and 2018 that did not meet program standards. After a comprehensive review of all stored specimen datasets, this data file was modified to remove records (5-<10% of records) that were initially included in error. No data values were altered. The sample weights and overall estimates were compared between the original and revised files. The sample weights provided with the original data release are appropriate to use with this updated data file; therefore, no new survey weights were created. The overall estimates from these files were examined and are consistent with the previous file. However, not all possible analyses were performed. For any queries related to this dataset please email the Biospecimen Program at serumplasmaurine@cdc.gov.

Component Description

All available sera from residual specimens from NHANES 2009-2010 participants were tested for Toxoplasma gondii by an enzyme immunoassay (EIA) that detects IgG antibodies against T. gondii. All results in this data release are reported as IU/ml. Samples with results ≥ 33 IU/mL should be coded as Positive, samples with results < 27 IU/mL should be coded as Negative, and samples with results ≥ 27 IU/mL and <33 IU/mL were considered Equivocal. All results originally considered Equivocal were repeated at least twice for confirmation and should be coded as Negative.

Eligible Sample

All specimens from 2009-2010 leftover from laboratories who tested them and sent the residual serum back to NCHS repository.

Description of Laboratory Methodology

Toxoplasma gondii antibodies were measured with a highly sensitive and specific Toxoplasma IgG enzyme immunoassay kit (Bio-Rad, Redmond, VA). This test utilizes antigen-coated wells. The samples are incubated in the antigen-coated wells, (if present) T. gondii antibodies are immobilized in the wells. Residual sample is eliminated by washing and conjugate (enzyme labeled antibodies to human IgG) is added and incubated. If IgG antibodies to T. gondii are present, the conjugate will be immobilized in the wells. Residual conjugate is eliminated by washing and the substrate is added. In the presence of the enzyme, the substrate is converted to a yellow end product which is read photometrically. Optical density was determined on a vMax microplate reader and computer equipped with SOFTmax software (Molecular Devices Corp., Menlo Park, CA).

Quality control samples are included on every plate. The results of serologic tests are of value as presumptive evidence of T. gondii infection. The test results are objective and normalized as index values, or as International Units (IU/mL), which are traceable to the WHO Anti-Toxoplasma Serum, 3rd International Standard Preparation, 1994. Prior to the study the Toxoplasma IgG EIA was evaluated using an established serum panel and comparison with the CDC Toxoplasma immunofluorescence assay and the Sabin-Feldman dye test and found to have a sensitivity and specificity of 100%.

Data Processing and Editing

Data were submitted after all the antibody testing was complete. The data were not edited.

Laboratory Quality Assurance and Monitoring

The Toxoplasma gondii EIA test is considered in control provided the quality control serum is within two standard deviations of its mean.

Analytic Notes

Results were measured as IU/ml. Samples with results ≥ 33 IU/mL should be coded as Positive, samples with results < 27 IU/mL should be coded as Negative, and samples with results ≥ 27 IU/mL and <33 IU/mL were considered Equivocal. All results originally considered Equivocal were repeated at least twice for confirmation and should be coded as Negative.

References

Atlman K. Toxoplasmosis, N.Y.State J. Med., 68(16):2151-2157, 1968.
Frenkel JK. Toxoplasma in and Around Us, Bioscience, 23: 343-352, 1973.
McLeod R and Remington JS, in Harrison’s Principles of Internal Medicine, McGraw-Hill Book Co., 879-885, 1980.
Remington JS, R McLeod, P Thulliez, G Desmonts. Toxoplasmosis. In JS Remington, JO Klein (ed). Infectious Diseases of the Fetus and Newborn Infant, 5th ed. Philadelphia: W.B. Saunders Co., 2001:205-346.
Remington JS. Toxoplasmosis in the Adult, Bull. N.Y. Acad.Med. 50(2):211-227, 1974.
Santoro F, D Afchain, R Pierce, et al. Serodiagnosis of toxoplasma infection using a purified parasite protein (P30). Clin Exp Immunol 1985;62:262-9.
Wilson M, JL Jones, JM McAuley. Toxoplasma. In PR Murray, EJ Baron, MA Pfaller, JH Jorgensen, RH Yolken (ed.), Manual of Clinical Microbiology, 8th ed. American Society for Microbiology, Washington, D.C., 2003:1970-1980.
Wilson M, Ware D. Evaluation of the Diagnostics Pasteur Platelia Toxo IgG and Toxo IgM kits for detection of human antibodies to Toxoplasma gondii. (Abstracts). Dallas: American Society of Microbiology, 1991.

Code or Value	Value Description	Count	Cumulative	Skip to Item
0 to 332	Range of Values	6670	6670
.	Missing	9	6679

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