ISSN: 1080-6059
Volume 13, Number 4–April 2007
Letter
Toxoplasma gondii Prevalence, United States
Jeffrey L. Jones,* 
Deanna Kruszon-Moran,† and Marianna Wilson*
*Centers for Disease Control and Prevention, Atlanta, Georgia, USA; and †Centers for Disease Control and Prevention, Hyattsville, Maryland, USA
Suggested citation for this article
To the Editor: We correct the prevalence of Toxoplasma gondii immunoglobulin (Ig) G antibodies published in Emerging Infectious Diseases in 2003 (1). An incorrect cutoff value in the computer program used to calculate seropositivity of anti–T. gondii IgG antibody resulted in some incorrect prevalence rates. We discovered this error when analyzing more recent National Health and Nutrition Examination Survey (NHANES) data.
The cutoff value for anti–T. gondii IgG seropositivity used in the prior publication (1) was >6 IU, which is the correct value for NHANES III 1988–1994 data (2) but not for NHANES 1999–2000 data. Because of a change by the T. gondii test kit manufacturer, the cutoff value for NHANES 1999–2000 seropositivity data was increased to >10 IU. This cutoff change from >6 to >10 IU does not cause a large difference in the T. gondii seroprevalence reported. In addition, it does not change the overall findings of the article or the overall relationship between NHANES III (1988–1994) and NHANES 1999–2000. However, it does produce a borderline change for 2 demographic subgroups (non-Hispanic white persons and persons born in the United States), for whom the difference from NHANES III to NHANES 1999–2000 data reached statistical significance at p<0.05 in the t test, but the 95% confidence intervals (CIs) for the prevalence estimates for these groups still overlapped between NHANES III and NHANES 1999–2000 (i.e., the t test is a less conservative measure of association than CI).
After this correction, the overall age-adjusted T. gondii antibody prevalence according to NHANES 1999–2000 data changed from 15.8% (95% CI 13.5%–18.1%) to 14.3% (95% CI 12.3%–16.2%). The Table shows the overall and stratified seroprevalence rates for NHANES 1999–2000 (corrected) compared with NHANES III (no corrections needed).
References
- Jones JL, Kruszon-Moran DK, Wilson M. Toxoplasma gondii infection in the United States, 1999–2000. Emerg Infect Dis. 2003;9:1371–4.
- Jones JL, Kruszon-Moran DK, Wilson M, McQuillan G, Navin T, McAuley JB. Toxoplasma gondii infection in the United States: seroprevalence and risk factors. Am J Epidemiol. 2001;154:357–65.
Table
Suggested Citation for this Article
Jones JL, Kruszon-Moran D, Wilson M. Toxoplasma gondii prevalence, United States [letter]. Emerg Infect Dis [serial on the Internet]. 2007 Apr [date cited]. Available from http://www.cdc.gov/EID/content/13/4/656.htm
Please use the form below to submit correspondence to the authors or contact them at the following address:
Jeffrey L. Jones, Centers for Disease Control and Prevention, Mailstop F22, 4770 Buford Highway, Atlanta, GA 30341, USA; email: JLJones@cdc.gov
Please note: To prevent email errors, please use no web addresses, email addresses, HTML code, or the characters <, >, and @ in the body of your message.
Please contact the EID Editors at eideditor@cdc.gov
The opinions expressed by authors contributing to this journal do not necessarily reflect the opinions of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
This page posted March 19, 2007
This page last reviewed March 22, 2007
Centers for Disease Control and Prevention, 1600 Clifton Rd, Atlanta, GA 30333, U.S.A
Tel: (404) 639-3311 / Public Inquiries: (404) 639-3534 / (800) 311-3435