Of the 4,875 persons 12–49 years of age who were selected for NHANES 1999–2000, a total of 4,602 (94.4%) persons were interviewed and underwent physician examination; of these, 4,234 persons (86.9% of those selected) had serum specimens tested for T. gondii antibodies. In NHANES 1999–2000, the percentage of those tested for T. gondii IgG antibodies among those examined did not vary by race/ethnicity, sex, or country of birth. Some variability existed, but no consistent trend, with age in the percentage of persons with sera tested among those examined (range 91% to 94%). Of the 4,234 persons tested for T. gondii IgG antibodies, 638 (15.8%, age-adjusted, 95% confidence limits [CL] 13.5, 18.1) were antibody positive. Among women (n=2,221), 14.9% (age-adjusted, 95% CL, 12.5, 17.4) were antibody positive. T. gondii antibody prevalence for men was similar to that for women (age-adjusted, 16.7% vs. 14.9%, respectively, p=0.28), higher among non-Hispanic blacks than among non-Hispanic whites (age-adjusted, 19.2% vs. 12.1%, p=0.003), and higher as age increased (). The T. gondii antibody prevalence was also higher in Mexican Americans than in non-Hispanic whites, but the difference was not statistically significant (16.8% vs. 12.1%, p=0.051). In NHANES III, the overall age-adjusted seroprevalence was similar for men and women and higher in Mexican Americans than in non-Hispanic whites in the age range examined for this article.
Comparison of Toxoplasma gondii immunoglobulin G antibody seroprevalence in NHANES 1999–2000 and NHANES III (1988–1994)a,b,c
No significant differences were found between NHANES 1999–2000 and NHANES III T. gondii
antibody prevalences overall or in any of the sex, race, or age categories (, comparing values horizontally by rows). In NHANES 1999–2000, children 6–11 years of age had a T. gondii
antibody prevalence of 8.0% (95% CL 4.5, 11.5, N=855) (data not shown in table). In NHANES III, the antibody prevalence for children 6–11 years of age was 5.2% (6
), however, as noted in Methods, this estimate may be subject to nonresponse error (data not shown in table).
The T. gondii antibody prevalence was higher in persons born outside the United States than in U.S.-born persons for both NHANES 1999–2000 and NHANES III (age-adjusted, 32.8% vs. 12.2% and 27.9% vs. 14.1%, respectively, ), but among persons born outside the United States seroprevalence did not differ significantly between NHANES 1999–2000 and NHANES III (p>0.05). In addition, the percentage of persons that were born outside the United States was not significantly different in NHANES 1999–2000 (16.3%, 95% CL 11.8%, 20.7%) compared with the percentage of persons born outside the United States in NHANES III (13.3%, 10.9%, 15.7%) (p>0.05).