Response rates for national population-based surveys have declined, including the National Health and Nutrition Examination Survey (NHANES). Declining response to the initial NHANES interview may impact consent and participation in downstream survey components such as record linkage, physical exams, storage of biological samples and phlebotomy. Interview response rates dropped from 68% in 2011-2012 to 53% in 2017-2018 for adults age 18 and older. Response was higher for children (1-17 years) but with a similar downward trend (2011-2012, 81%; 2017-2018, 65%). Despite declining interview response rates, changes in consent and response rates for downstream components over time have been mixed. Among those interviewed, the examination response rate was over 93%, consent for record linkage was over 90%, and consent for storage of specimens for future research was over 99%. The availability of a blood sample for storage ranged between 60%-65% for children and 78%-85% for adults.

BACKGROUND: Toxoplasma gondii and Toxocara are common parasites that infect humans globally. Our aim was to examine the relationship between T. gondii and Toxocara infection and cognition. METHODS: Multivariate logistic regression was used to test the association of T. gondii and Toxocara seropositivity on indices of cognitive function (a word list learning trial with delayed recall from the Consortium to Establish a Registry for Alzheimer's Disease, an animal fluency test (AFT) and a digit symbol substitution test (DSST)) among 2643 adults aged 60 years and older in the 2011-2014 National Health and Nutrition Examination Survey. RESULTS: Seropositivity to T. gondii or Toxocara were both associated with lower scores in all three cognitive function measures examined in univariate analyses. Except for the DSST, these associations were not significant after adjustment for age, gender, race and Hispanic origin, poverty level, education, US birth status, depression and hypertension. On stratification to account for significant interactions, Toxocara seropositivity was associated with worse scores on the AFT among those born outside the USA, worse scores on the DSST among those aged 60-69 years, female, Hispanic and with a high school diploma or less. Lower DSST scores with Toxocara infection was greater for adults living below compared with at or above the poverty level. CONCLUSIONS: Seropositivity to these parasites, particularly to Toxocara, may be associated with diminished cognitive performance in certain subgroups of older adults.

CDC COVID-19 surveillance systems monitor SARS-CoV-2 antibody prevalence to collect information about asymptomatic, undiagnosed, and unreported disease using national convenience samples of blood donor data from commercial laboratories (1,2). However, nonrandom sampling of data from these systems could affect prevalence estimates (1-3). The National Health and Nutrition Examination Survey (NHANES) collects SARS-CoV-2 serology data among a sample of the general U.S. civilian population (4). In addition, NHANES collects self-reported COVID-19 vaccination and disease history, and its statistical sampling design is not based on health care access or blood donation. Therefore, NHANES data can be used to better quantify asymptomatic SARS-CoV-2 infection prevalence and seropositivity attained through infection without vaccination. Preliminary NHANES 2021-2022 results indicated that 41.6% of adults aged ≥18 years had serology indicative of past infection and that 43.7% of these adults, including 57.1% of non-Hispanic Black or African American (Black) adults, reported never having had COVID-19, possibly representing asymptomatic infection. In addition, 25.5% of adults whose serology indicated past infection reported never having received COVID-19 vaccination. Prevalences of seropositivity in the absence of vaccination were higher among younger adults and Black adults, reflecting the lower observed vaccination rates among these groups (5). These findings raise health equity concerns given the disparities observed in SARS-CoV-2 infection and COVID-19 vaccination. Results from NHANES 2021-2022 can guide ongoing efforts to achieve vaccine equity in COVID-19 primary vaccination series and booster dose coverage.

Cytomegalovirus (CMV) seroprevalence among US children aged 1–5 years was 28.2% during 2017–2018 in the National Health and Nutrition Examination Survey (NHANES) [1]. Here, we provide updated estimates of CMV immunoglobulin G (IgG) seroprevalence using the larger NHANES 2017–March 2020 pre-pandemic dataset.

During the 2017-2018 National Health and Nutrition Examination Survey, urine samples from participants aged 14-59 years were tested for Mycoplasma genitalium infection. Overall prevalence was 1.7% (95% CI: 1.1%, 2.7%). Prevalence was similar between males (1.8%, 95% CI: 0.9%, 3.1%) and females (1.7%, 95% CI: 0.8%, 3.0%).

BACKGROUND: HIV antibody testing has been included in the National Health and Nutrition Examination Survey, for ages 18-49 since 1999 and for ages 18-59 years since 2009 enabling estimation of trends in HIV prevalence as part of national surveillance in the U.S. household population. Self-reported HIV testing and antiretroviral (ARV) use was also included in the survey since 1999. SETTING: A continuous household-based probability sample of the U.S. population. METHODS: From 1999-2018, 29,020 participants age 18-49 years were tested for HIV antibody and 34,092 participants age 18-59 years were asked about self-report of any previous HIV testing. RESULTS: HIV prevalence was 0.41% among those aged 18-59 in 2009-2018 with a non-significant trend over time among those aged 18-49 years from 1999-2002 to 2015-2018. However, significant declines in prevalence were seen among those aged 18-39 years (0.37% to 0.11%), women (0.22% to 0.06%) and non-Hispanic black persons (2.14% to 0.80%). Participants age aged 18-39 self-reported a decline in HIV testing while those aged 40-49 and 50-59 years, non-Hispanic black persons and women reported an increase in getting a HIV test. Prevalence of infection and self-reported history of HIV testing varied by demographic and risk groups. HIV testing among HIV positive persons was 83.9%. ARV therapy among those HIV positive was under 50%. CONCLUSION: Though total HIV prevalence and previous self-reported HIV testing remained stable for the last 20 years, there were significant declines in age and demographic subgroups. Prevalence for both outcomes varied by demographic and risk variables.

Dear Editor, Petersen et al reported that cytomegalovirus (CMV) seroprevalence among U.S. children aged 1–5 years in the National Health and Nutrition Examination Survey (NHANES) increased from 20.7% in 2011–2012 to 28.2% in 2017–2018, with significant increases among 1-year-olds, non-Hispanic White children, those living at or above the poverty level, and being the only child ≤5 years in the household [1]. As we previously reported, 2011–2012 NHANES results indicated that these groups had significantly lower CMV seroprevalence in comparison to children that were older, Hispanic, living below the poverty level, and living with another child ≤5 years in the household, respectively [2, 3].

We report supplemental findings incorporating Toxoplasma gondii serology results from our study of risk factors for Toxocara seropositivity in the United States [1] using stored serum samples collected from the National Health and Nutrition Examination Survey (NHANES), 2011–2014. Whereas T. gondii is a protozoan parasite and Toxocara is an intestinal nematode, both share ingestion of contaminated soil as means of exposure in humans. Both parasites can contaminate soil when environmentally resistant T. gondii oocysts or Toxocara cati eggs are shed in the feces of infected cats [2, 3].

Toxoplasma gondii can cause severe neurologic and ocular disease when transmitted congenitally and in immunosuppressed persons. Sera collected in the National Health and Nutrition Examination Survey 2011 through 2014 in 13,507 persons >/= 6 years old were tested for T. gondii immunoglobulin (Ig) G and IgM antibodies, and in those both IgG and IgM antibody positive, for IgG avidity. Overall, 11.14% (95% confidence limits [CL] 9.88%, 12.51%) were seropositive for T. gondii IgG antibody (age-adjusted seroprevalence 10.42% [95% CL 9.19%, 11.76%]); in women aged 15-44 years, the age-adjusted T. gondii IgG seroprevalence was 7.50% (95% CL 6.00%, 9.25%). In multivariable analysis, risk for IgG seropositivity increased with age and was higher in males; persons living below the poverty level; persons with </= a high school education compared with those with > a high school education; and non-Hispanic black, Mexican American, and foreign born non-Hispanic white persons compared with U.S.-born non-Hispanic white persons. Overall, 1.16% (95% CL 0.94%, 1.42%) were T. gondii IgM antibody positive and 0.71%, (95% CL 0.54%, 0.92%) were both IgM and IgG antibody positive. In multivariable analysis, the significant risk factors for being both IgM and IgG positive were age, crowding, and non-U.S. birth origin compared with U.S.-born persons. Among those positive for both IgM and IgG antibody, almost all had high avidity (all women aged 15-44 years had high avidity). Toxoplasma gondii antibody prevalence remains relatively low in the United States, although it is higher in non-U.S.-born persons, males, and some minority and socioeconomically disadvantaged groups.

Congenital cytomegalovirus (CMV) infection may occur as a consequence of primary or nonprimary maternal infection during pregnancy (1). Postnatal CMV infection may develop in up to 40% of infants who are fed breast milk for ≥1 month by a CMV-seropositive mother (1). Further spread of CMV may result from child-to-child transmission in the household or day care center (2). | In the 2011–2012 National Health and Nutrition Examination Survey (NHANES), overall CMV IgG seroprevalence among U.S. children 1 to 5 years of age was 21%, with a significant increase among those who were 5 years old (31%) compared to those who were 1 year old (12%) (3). CMV seroprevalence was significantly higher among non-Hispanic black (25%) and Hispanic (31%) children than among non-Hispanic white children (11%) and among children living below versus at or above the poverty line (31% versus 15%) (3). Here, we describe additional results for the history of breastfeeding and number of household children ≤5 years old. | NHANES, a nationally representative cross-sectional survey of the civilian noninstitutionalized U.S. population (4), included CMV antibody testing for 699 (62%) of the 1,135 children who were 1 to 5 years old examined in 2011 to 2012. To assess independent predictors of CMV IgG seroprevalence, we repeated the analysis as described in the previous report (3) and performed additional logistic-regression modeling on 636 children with complete data (out of the 682 children in the survey born in the 50 U.S. states and the District of Columbia). We performed all analyses using SUDAAN version 9.0 (Research Triangle Institute, Research Triangle Park, NC); results for which the P value was <0.05 were considered statistically significant.

Background: Toxocariasis results from infection with larval stages of a dog and cat intestinal nematode and causes human morbidity. The current US estimate of Toxocara exposure is 13.9% (NHANES III 1988-1994). Methods: We used a multiplex bead based assay (Tc-CTL-1MBA) with purified Toxocara canis antigen to estimate Toxocara antibody seroprevalence in serum of 13,509 persons six years and older from the National Health and Nutrition Examination Survey (NHANES), 2011-2014 and identified seropositivity risk factors. We tested a subset of 500 samples with the previously used T. canis enzyme immunoassay to estimate seroprevalence had prior samples been tested by Tc-CTL-1MBA. Results: The age standardized estimate of Toxocara seroprevalence was 5.0% (95% confidence interval [CI], 4.2%-5.8%), lower than previously reported even adjusting for increased Tc-CTL-1MBA specificity. Risk factors for seropositivity from multiple logistic regression were older age (odds ratio [OR], 2.1; 95%CI, 1.1-3.9 in persons 50-59 years old; OR, 1.7; 95%CI, 1.0-2.8 in persons 60-69; and OR, 2.6; 95%CI, 1.5-4.7 in persons ≥70 versus persons 6-11), non-Hispanic Black race/Hispanic origin (OR, 1.4; 95%CI, 1.0-2.0) versus non-Hispanic White, male sex (OR, 1.9; 95%CI, 1.6-2.2), living below poverty level (OR, 1.9; 95%CI, 1.4-2.6), households with ≥0.5 persons per room (OR, 1.3; 95%CI, 1.0-1.6), less than college education (OR, 1.9; 95%CI, 1.5-2.4), and birth outside the United States (OR, 3.6; 95%CI, 2.6-5.1). Conclusions: Toxocara seroprevalence estimates in 2011-14 were lower than in a study from NHANES III, 1988-94, but seropositivity risk factors remained the same and should continue to be the focus of prevention efforts.

Background Higher cumulative burden of viral and bacterial pathogens may increase the risk of stroke, but the contribution of parasitic infections in relation to cumulative pathogen burden and risk of stroke has rarely been examined. Aim To estimate the association of multiple persistent viral and parasitic infections with stroke in a representative sample of adults in the United States. Methods Serological evidence of prior infection was categorized as positive for 0-1, 2, 3, or 4-5 infections based on immunoglobulin G seropositivity to cytomegalovirus, hepatitis A virus, hepatitis B virus, Toxoplasma gondii, and Toxocara spp. in 13,904 respondents from the National Health and Nutrition Examination Survey III. Regression analysis was used to estimate the cross-sectional association between serological evidence of prior infection and history of stroke adjusting for demographic risk factors, and potential mediators of stroke. Results Age-adjusted models that included serological evidence of prior infection to cytomegalovirus, hepatitis A virus, hepatitis B virus, Toxoplasma gondii, and Toxocara spp. showed that adults in the highest serological evidence of prior infection category (4-5 infections) had a higher prevalence of stroke (5.50%, 95% confidence interval 2.44-10.46%) than those in the lowest serological evidence of prior infection categories (1.49%, 95% confidence interval 1.01-2.11%), and a trend test suggested a graded association between serological evidence of prior infection and stroke ( p = 0.02). In multivariable logistic regression models, the positive association of serological evidence of prior infection with stroke prevalence remained significant after adjustment for other significant risk factors (odds ratio = 1.4, p = 0.01) but was only significant among those aged 20-59 (odds ratio = 2.0, p = 0.005) and not among those aged 60-69 ( p = 0.78) or 70 and older ( p = 0.43). Conclusion We found support for a connection between serological evidence of prior infection to cytomegalovirus, hepatitis A virus, hepatitis B virus, Toxoplasma gondii, and Toxocara spp. and stroke among those aged 20-59. There may be a need to consider common parasitic infections in addition to viral and bacterial pathogens when calculating serological evidence of prior infection in relation to cerebrovascular disease.

OBJECTIVE: To assess the influence of parity, as a proxy for exposure to children, and sexual history on cytomegalovirus (CMV) seroprevalence. METHODS: Data were retrospectively analyzed from women aged 20-49 years who were tested for CMV immunoglobulin G antibodies in the 1999-2004 National Health and Nutrition Examination Survey, a nationally representative survey of the US population. Logistic regression was used to determine independent variables associated with CMV seroprevalence. RESULTS: Among 3710 women, the age-adjusted CMV seroprevalence was 61.3% (95% CI 58.9%-63.6%). In age-adjusted univariate analysis, women who had given birth at least once had higher overall CMV seroprevalence (66.0%, 95% CI 63.1%-68.9%) than did those who had not given birth (49.0%, 95% CI 44.4%-53.7%; P<0.001). In multivariate logistic analysis, higher CMV seroprevalence was independently associated with number of live births (each additional birth: adjusted odds ratio [aOR] 1.2, 95% CI 1.1-1.3), age at first sexual intercourse (<18 vs ≥18years: aOR 1.3, 95% CI 1.1-1.6), lifetime sexual partners (≥10 vs <10: aOR 1.4, 95% CI 1.1-1.9), and herpes type 2 seropositivity (aOR 1.9, 95% CI 1.5-2.6) after controlling for age, race/Hispanic origin, place of birth, poverty index, and education. CONCLUSION: Among US women of reproductive age, parity and sexual exposures were independently associated with increased CMV seroprevalence.

IMPORTANCE: Between 1980 and 2000, the prevalence of obesity increased significantly among adult men and women in the United States; further significant increases were observed through 2003-2004 for men but not women. Subsequent comparisons of data from 2003-2004 with data through 2011-2012 showed no significant increases for men or women. OBJECTIVE: To examine obesity prevalence for 2013-2014 and trends over the decade from 2005 through 2014 adjusting for sex, age, race/Hispanic origin, smoking status, and education. DESIGN, SETTING, AND PARTICIPANTS: Analysis of data obtained from the National Health and Nutrition Examination Survey (NHANES), a cross-sectional, nationally representative health examination survey of the US civilian noninstitutionalized population that includes measured weight and height. EXPOSURES: Survey period. MAIN OUTCOMES AND MEASURES: Prevalence of obesity (body mass index ≥30) and class 3 obesity (body mass index ≥40). RESULTS: This report is based on data from 2638 adult men (mean age, 46.8 years) and 2817 women (mean age, 48.4 years) from the most recent 2 years (2013-2014) of NHANES and data from 21,013 participants in previous NHANES surveys from 2005 through 2012. For the years 2013-2014, the overall age-adjusted prevalence of obesity was 37.7% (95% CI, 35.8%-39.7%); among men, it was 35.0% (95% CI, 32.8%-37.3%); and among women, it was 40.4% (95% CI, 37.6%-43.3%). The corresponding prevalence of class 3 obesity overall was 7.7% (95% CI, 6.2%-9.3%); among men, it was 5.5% (95% CI, 4.0%-7.2%); and among women, it was 9.9% (95% CI, 7.5%-12.3%). Analyses of changes over the decade from 2005 through 2014, adjusted for age, race/Hispanic origin, smoking status, and education, showed significant increasing linear trends among women for overall obesity (P = .004) and for class 3 obesity (P = .01) but not among men (P = .30 for overall obesity; P = .14 for class 3 obesity). CONCLUSIONS AND RELEVANCE: In this nationally representative survey of adults in the United States, the age-adjusted prevalence of obesity in 2013-2014 was 35.0% among men and 40.4% among women. The corresponding values for class 3 obesity were 5.5% for men and 9.9% for women. For women, the prevalence of overall obesity and of class 3 obesity showed significant linear trends for increase between 2005 and 2014; there were no significant trends for men. Other studies are needed to determine the reasons for these trends.

IMPORTANCE: Previous analyses of obesity trends among children and adolescents showed an increase between 1988-1994 and 1999-2000, but no change between 2003-2004 and 2011-2012, except for a significant decline among children aged 2 to 5 years. OBJECTIVES: To provide estimates of obesity and extreme obesity prevalence for children and adolescents for 2011-2014 and investigate trends by age between 1988-1994 and 2013-2014. DESIGN, SETTING, AND PARTICIPANTS: Children and adolescents aged 2 to 19 years with measured weight and height in the 1988-1994 through 2013-2014 National Health and Nutrition Examination Surveys. EXPOSURES: Survey period. MAIN OUTCOMES AND MEASURES: Obesity was defined as a body mass index (BMI) at or above the sex-specific 95th percentile on the US Centers for Disease Control and Prevention (CDC) BMI-for-age growth charts. Extreme obesity was defined as a BMI at or above 120% of the sex-specific 95th percentile on the CDC BMI-for-age growth charts. Detailed estimates are presented for 2011-2014. The analyses of linear and quadratic trends in prevalence were conducted using 9 survey periods. Trend analyses between 2005-2006 and 2013-2014 also were conducted. RESULTS: Measurements from 40,780 children and adolescents (mean age, 11.0 years; 48.8% female) between 1988-1994 and 2013-2014 were analyzed. Among children and adolescents aged 2 to 19 years, the prevalence of obesity in 2011-2014 was 17.0% (95% CI, 15.5%-18.6%) and extreme obesity was 5.8% (95% CI, 4.9%-6.8%). Among children aged 2 to 5 years, obesity increased from 7.2% (95% CI, 5.8%-8.8%) in 1988-1994 to 13.9% (95% CI, 10.7%-17.7%) (P < .001) in 2003-2004 and then decreased to 9.4% (95% CI, 6.8%-12.6%) (P = .03) in 2013-2014. Among children aged 6 to 11 years, obesity increased from 11.3% (95% CI, 9.4%-13.4%) in 1988-1994 to 19.6% (95% CI, 17.1%-22.4%) (P < .001) in 2007-2008, and then did not change (2013-2014: 17.4% [95% CI, 13.8%-21.4%]; P = .44). Obesity increased among adolescents aged 12 to 19 years between 1988-1994 (10.5% [95% CI, 8.8%-12.5%]) and 2013-2014 (20.6% [95% CI, 16.2%-25.6%]; P < .001) as did extreme obesity among children aged 6 to 11 years (3.6% [95% CI, 2.5%-5.0%] in 1988-1994 to 4.3% [95% CI, 3.0%-6.1%] in 2013-2014; P = .02) and adolescents aged 12 to 19 years (2.6% [95% CI, 1.7%-3.9%] in 1988-1994 to 9.1% [95% CI, 7.0%-11.5%] in 2013-2014; P < .001). No significant trends were observed between 2005-2006 and 2013-2014 (P value range, .09-.87). CONCLUSIONS AND RELEVANCE: In this nationally representative study of US children and adolescents aged 2 to 19 years, the prevalence of obesity in 2011-2014 was 17.0% and extreme obesity was 5.8%. Between 1988-1994 and 2013-2014, the prevalence of obesity increased until 2003-2004 and then decreased in children aged 2 to 5 years, increased until 2007-2008 and then leveled off in children aged 6 to 11 years, and increased among adolescents aged 12 to 19 years.

BACKGROUND: The number of persons with chronic hepatitis B virus (HBV) infection in the United States is affected by diminishing numbers of young persons who are susceptible because of universal infant vaccination since 1991, offset by numbers of HBV-infected persons migrating to the United States from endemic countries. METHODS: The prevalence of HBV infection was determined by serologic testing and analysis among non-institutionalized persons aged 6 years and older for: antibody to hepatitis B core antigen (anti-HBc), indicative of prior HBV infection; hepatitis B surface antigen (HBsAg), indicative of chronic (current) infection; and antibody to hepatitis B surface antigen(anti-HBs), indicative of immunity from vaccination. These prevalence estimates were analyzed in three periods of the National Health and Nutrition Examination Survey (NHANES): 1988-1994 (21,260 persons); 1999-2008 (29,828); and 2007-2012 (22,358). In 2011-2012, for the first time, non-Hispanic Asians were oversampled sampled in NHANES. RESULTS: For the most recent period (2007-2012), 3.9% had anti-HBc, indicating about 10.8 (95% CI 9.4-12.2) million non-institutionalized US residents having ever been infected with HBV. The overall prevalence of chronic HBV infection has remained constant since 1999: 0.3% (95% confidence intervals, 0.2% - 0.4%), and since 1999, prevalence of chronic HBV infection among non-Hispanic blacks has been 2-3 fold greater than the general population. An estimated 3.1% (1.8% - 5.2%) of non-Hispanic Asians were chronically infected with HBV during 2011-2012; which reflects a 10-fold greater prevalence than the general population. Adjusted prevalence of vaccine induced immunity increased 16% since 1999, and the number of persons (mainly young) with serologic evidence of vaccine-protection from HBV infection rose from 57.8 (95% CI 55.4-60.1) million to 68.5 (95% CI 65.4-71.2) million. CONCLUSION: Despite increasing immune protection in young persons vaccinated in infancy, an analysis of chronic hepatitis B prevalence in racial and ethnic populations indicates that during 2011-2012 there were 847,000 HBV infections (which included approximately 400,000 non-Hispanic Asians) in the non-institutionalized US population.

BACKGROUND: In the United States, measles, mumps, rubella, and varicella immunity is now primarily achieved through vaccination. Monitoring population immunity is necessary. METHODS: We evaluated seroprevalence of antibodies to measles, mumps, rubella, and varicella using the National Health and Nutrition Examination Survey during 2009-2010. RESULTS: Measles, mumps, rubella, and varicella seroprevalence was 92.0% (95% confidence interval [CI], 90.9%-93.0%), 87.6% (CI, 85.8%-89.2%), 95.3% (CI, 94.3%-96.2%), and 97.8% (CI, 97.1%-98.3%), respectively. United States (US)-born persons had lower mumps seroprevalence and higher varicella seroprevalence than non-US born persons. CONCLUSIONS: Seroprevalence was high (88%-98%) for all 4 viruses in the US population during 2009-2010.

Cytomegalovirus (CMV) seroprevalence among U.S. children 1-5 years-old was assessed in the National Health and Nutrition Examination Survey 2011-2012. Overall seroprevalence (95% confidence interval) of IgG was 20.7% (14.4-28.2%), IgM 1.1% (0.4-2.4%), and low IgG avidity 3.6% (1.7-6.6%), corresponding to a 17.3% (10.1-26.7%) prevalence of recent infection among IgG-positive children.

OBJECTIVE: To examine changes in the prevalence of HIV testing among adults following CDC's 2006 revised HIV testing recommendations. DESIGN: The 2003-2010 National Health and Nutrition Examination Survey (NHANES), a nationally representative, cross-sectional survey of the non-institutionalized U.S. population. METHODS: Weighted estimates and multivariable modeling to assess prevalence of lifetime HIV testing, outside of blood donations, based on 13,975 respondents aged 18-59 years, comparing NHANES 2003-2006 and 2007-2010. RESULTS: Overall, HIV testing was 42.1% during 2003-2006 and 44.5% during 2007-2010 (p>0.05). After adjusting for significant predictors in a multivariate model, HIV testing increased from 2003-2006 to 2007-2010 (adjusted odds ratio [aOR] 1.14, p<0.05), mostly among males (aOR 1.33, p<0.001) as compared to females (aOR 1.02, p>0.05). HIV testing also increased significantly among non-Hispanic blacks, heterosexuals, those aged 50-59 years, those without a sexually transmitted infection (STI) history, those without health insurance and those who did not access healthcare in the past year. HIV testing did not change significantly among high-risk groups, including men who have sex with men, those with a history of injection or illicit drug use and those with a STI history. CONCLUSION: In multivariate modeling, we found a modest but significant increase in HIV testing overall and among males after publication of the revised recommendations for HIV testing. The significant increase in non-high risk groups suggests an expansion in generalized HIV testing, as recommended. However, even in 2007-2010, 56% of the U.S. population has never been tested for HIV.

PURPOSE: To examine the relationship between infection with Toxoplasma gondii (toxo) and cognition. METHODS: Multivariate logistic regression was used to test the association of toxo seropositivity with indices of cognitive function among over 4,200 adults in the third National Health and Nutrition Examination Survey. RESULTS: Toxo-seropositive participants were more likely than seronegative participants to score in the worst quartile of the simple reaction time test (OR 1.3, 95 % CI 1.0, 1.6), symbol-digit substitution test (SDST, OR 1.5, 95 % CI 1.2, 1.9) and the serial-digit learning test (trials to criterion) (SDLTNT, OR 1.4, 95 % CI 1.1, 1.8) in models adjusted for age, race/ethnicity, gender and foreign birth. After further adjustment for all cofactors, the association between toxo seropositivity and these outcomes was no longer significant. However, seropositivity was associated with worse scores on the SDST (OR 2.9, 95 % CI 1.8, 4.8) among those in the lowest income category and the SDLTNT (OR 1.5, 95 % CI 1.1, 2.5) among those foreign born. CONCLUSIONS: Toxo seropositivity may be associated with poor cognitive test scores in certain subgroups; however, causation cannot be established in this cross-sectional study.

Toxoplasma gondii is a ubiquitous parasite that can cause neurologic and ocular disease. We tested sera from 7,072 people ≥ 6 years of age in the 2009-2010 National Health and Nutrition Examination Survey (NHANES) for immunoglobulin G antibodies and compared these results with two previous NHANES surveys. The overall T. gondii antibody seroprevalence among persons ≥ 6 years of age in 2009-2010 was 13.2% (95% confidence limit [CL] 11.8%, 14.5%) and age-adjusted seroprevalence was 12.4% (95% CL 11.1%, 13.7%); age-adjusted seroprevalence among women 15-44 years of age was 9.1% (95% CL 7.2%, 11.1%). In U.S. born persons 12-49 years of age, the age-adjusted T. gondii seroprevalence decreased from 14.1% (95% CL 12.7%, 15.5%) in NHANES III (1988-1994) to 9.0% (95% CL 7.6%, 10.5%) in NHANES 1999-2004 to 6.7% (95% CL 5.3%, 8.2%) in NHANES 2009-2010 (P < 0.001 linear trend). Although T. gondii antibody presence is still relatively common, the prevalence in the United States has continued to decline.

BACKGROUND: Toxoplasma gondii (T. gondii) is a neurotropic protozoan parasite that causes persistent infection in humans. A substantial literature suggests that schizophrenia is associated with increased seroprevalence of T. gondii, but a possible link of the parasite with mood disorders has not been as thoroughly investigated. METHODS: We examined the association of Toxoplasma-specific immunoglobulin G results with mood disorder outcomes in 7440 respondents from the third National Health and Nutrition Survey, which is a nationally representative sample of the United States noninstitutionalized civilian population. Regression models were adjusted for numerous potential confounders, including tobacco smoking and C-reactive protein levels. RESULTS: No statistically significant associations were found between T. gondii seroprevalence and a history of major depression (n = 574; adjusted odds ratio [OR]: .8; 95% confidence interval [CI]: .5-1.2), severe major depression (n = 515; adjusted OR: .8; 95% CI: .6-1.2), dysthymia (n = 548; adjusted OR: 1.1; 95% CI: .7-1.8), or dysthymia with comorbid major depression (n = 242, adjusted OR: 1.2; 95% CI: .6-2.4), all p values were > .05, including analysis stratified by gender. However, there was a significant relationship between T. gondii seroprevalence and bipolar disorder type I for respondents in which both manic and major depression symptoms were reported (n = 41; adjusted OR: 2.4; 95% CI: 1.2-4.8; p < .05). CONCLUSIONS: In a population-based sample, T. gondii seroprevalence is not elevated in unipolar mood disorders but is higher in a subset of respondents with a history of bipolar disorder type 1.

BACKGROUND: We report the first population-based assessment of national trends in chlamydia prevalence in the United States. METHODS: We investigated trends in chlamydia prevalence in representative samples of the US population aged 14 to 39 years using data from five 2-year survey cycles of the National Health and Nutrition Examination Survey from 1999 to 2008. Prevalence estimates and 95% confidence intervals (CI) are reported stratified by age, gender, and race/ethnicity. Percent change in prevalence over this time period was estimated from regression models. RESULTS: In the 2007-2008 cycle, chlamydia prevalence among participants aged 14 to 39 years was 1.6% (95% CI: 1.1%-2.4%). Prevalence was higher among females (2.2%, 95% CI: 1.4%-3.4%) than males (1.1%, 95% CI: 0.7%-1.7%). Prevalence among non-Hispanic black persons was 6.7% (95% CI: 4.6%-9.9%) and was 2.5% (95% CI: 1.6%-3.8%) among adolescents aged 14 to 19 years. Over the five 2-year cycles, there was an estimated 40% reduction (95% CI: 8%-61%) in prevalence among participants aged 14 to 39 years. Decreases in prevalence were notable in men (53% reduction, 95% CI: 19%-72%), adolescents aged 14 to 19 years (48% reduction, 95% CI: 11%-70%), and adolescent non-Hispanic black persons (45%, reduction, 95% CI: 4%-70%). There was no change in prevalence among females aged 14 to 25 years, the population targeted for routine annual screening. CONCLUSIONS: On the basis of population estimates of chlamydia prevalence, the overall chlamydia burden in the United States decreased from 1999 to 2008. However, there remains a need to reduce prevalence in populations most at risk and to reduce racial disparities.

OBJECTIVES: We described seroprevalence of antibody to hepatitis A virus (anti-HAV) in the United States during 1999-2006 and compared it with seroprevalence before the availability of vaccine. METHODS: We analyzed data from the 1988-1994 and 1999-2006 National Health and Nutrition Examination Survey (NHANES) to obtain estimates of anti-HAV seroprevalence for the U.S. household population. We grouped region of residence based on the 1999 Advisory Committee on Immunization Practices recommendations into 17 states with any recommendation (vaccinating) and 33 states without any recommendation (non-vaccinating). RESULTS: During 1999-2006, the overall seroprevalence of anti-HAV was 34.9% (95% confidence interval [CI] 33.1, 36.7). During 1999-2006, U.S.-born children living in vaccinating states (33.8%, 95% CI 26.2, 42.2) had a higher seroprevalence than children in non-vaccinating states (11.0%, 95% CI 9.4, 12.8; p < 0.001). Seroprevalence among children increased from 8.0% (95% CI 6.3, 10.1) during 1988-1994 to 20.2% (95% CI 16.0, 24.8) during 1999-2006 (p < 0.001). For U.S.-born children aged 6-19 years, the strongest factor associated with seroprevalence was residence in vaccinating states. Among U.S.-born adults aged > 19 years, the overall age-adjusted seroprevalence of anti-HAV was 29.9% (95% CI 28.3, 31.5) during 1999-2006, which was not significantly different from the seroprevalence during 1988-1994 (32.2%, 95% CI 30.1, 34.4). CONCLUSIONS: Increases in seroprevalence among children in vaccinating states suggest a positive effect of the 1999 vaccination recommendations.

OBJECTIVE: We estimated the varicella seroprevalence among the U.S. population aged 6-49 years based on retested National Health and Nutrition Examination Survey (NHANES) specimens collected between 1999 and 2004--originally tested using a method unsuitable for detecting vaccine-induced immunity--and compared it with historical estimates. METHODS: We performed a confirmatory test suitable for detecting vaccine-induced immunity on all available specimens from 6- to 19-year-olds who originally tested negative (n = 633), and on 297 randomly selected specimens that had tested positive. Retest results superseded original results for determining seroprevalence. We assessed seroprevalence for the entire sample aged 6-49 years (n = 16,050) by participant demographic characteristics and compared it with historical estimates (NHANES 1988-1994). RESULTS: The percentage of false-negative results for the original test was higher for specimens from younger children (6-11 years of age: 27.5%; 12-19 years of age: 13.3%) and for specimens collected most recently (2001-2004: 26.0%; 1999-2000: 12.6%). The age-adjusted rate of varicella seroprevalence for 1999-2004 was 93.6% for 6- to 19-year-olds and 98.0% for adults aged 20-49 years compared with 90.0% and 98.1%, respectively, for 1988-1994. We found an increase in seropositivity between the survey periods, from 93.2% to 97.2% (p < 0.001) among 12- to 19-year-olds. For children, non-Hispanic black ethnicity and younger age were associated with lower seroprevalence in both survey periods. CONCLUSIONS: Varicella seroprevalence increased with age among children and was uniformly high in the U.S. adult population between 1999 and 2004. The original testing produced false-negative seroprevalence results among children's specimens collected between 1999 and 2004 from 6- to 19-year-olds.

BACKGROUND: In 2006, the largest mumps outbreak in the United States in 20 years occurred. To understand prior mumps seroprevalence and factors associated with the presence of antibody to mumps virus, data from the 1999-2004 National Health and Nutrition Examination Survey (NHANES) were analyzed. METHODS: A mumps virus-specific enzyme immunoassay was used to measure the seroprevalence of serum immunoglobulin G (IgG) antibody among NHANES participants aged 6-49 years. Participants were grouped on the basis of 10-year birth cohorts, 95% confidence intervals (CIs) were calculated using SUDAAN software, and logistic regression was used to identify independent predictors. RESULTS: The overall age-adjusted seroprevalence of IgG antibody to mumps virus during 1999-2004 was 90.0% (95% CI, 88.8%-91.1%). Seroprevalence was higher among US-born non-Hispanic blacks (96.4% [95% CI, 95.5%-97.2%]) and non-US-born Mexican Americans (93.7% [95% CI, 92.0%-95.2%]). Seroprevalence was significantly lower in the 1967-1976 birth cohort (85.7% [95% CI, 83.5%-87.8%]). The variables sex, education, and race/ethnicity/birthplace were independent predictors in at least 1 of the birth cohorts. CONCLUSIONS: The overall estimate of 90.0% is at the lower end of the estimated population immunity (90%-92%) needed to achieve herd immunity. Lower seroprevalence among groups suggest that they represent populations at an increased risk. For mumps control, high vaccine coverage and high population immunity must be achieved and maintained.

BACKGROUND: Our objective was to assess trends in the prevalence of hepatitis B virus (HBV) infection in the United States after widespread hepatitis B vaccination. METHODS: The prevalence of HBV infection and immunity was determined in a representative sample of the US population for the periods 1999-2006 and 1988-1994. National Health and Nutrition Examination Surveys participants 6 years of age were tested for antibody to hepatitis B core antigen (anti-HBc), hepatitis B surface antigen (HBsAg), and antibody to hepatitis B surface antigen (anti-HBs). Prevalence estimates were weighted and age-adjusted. RESULTS: During the period 1999-2006, age-adjusted prevalences of anti-HBc (4.7%) and HBsAg (0.27%) were not statistically different from what they were during 1988-1994 (5.4% and 0.38%, respectively). The prevalence of anti-HBc decreased among persons 6-19 years of age (from 1.9% to 0.6%; [Formula: see text]) and 20-49 years of age (from 5.9% to 4.6%; [Formula: see text]) but not among persons 50 years of age (7.2% vs 7.7%). During 1999-2006, the prevalence of anti-HBc was higher among non-Hispanic blacks (12.2%) and persons of "Other" race (13.3%) than it was among non-Hispanic whites (2.8%) or Mexican Americans (2.9%), and it was higher among foreign-born participants (12.2%) than it was among US-born participants (3.5%). Prevalence among US-born children 6-19 years of age (0.5%) did not differ by race or ethnicity. Disparities between US-born and foreign-born children were smaller during 1999-1996 (0.5% vs 2.0%) than during 1988-1994 (1.0% vs 12.8%). Among children 6-19 years of age, 56.7% had markers of vaccine-induced immunity. CONCLUSIONS: HBV prevalence decreased among US children, which reflected the impact of global and domestic vaccination, but it changed little among adults, and approximately 730,000 US residents (95% confidence interval, 550,000-940,000) are chronically infected.

We performed serum testing for IgG antibodies against Coxiella burnetii (phase I and phase II) and analyzed questionnaire data from 4,437 adults > or = 20 years of age who participated in the National Health and Nutrition Examination Survey 2003-2004 survey cycle. National Q fever seroprevalence was determined by enzyme-linked immunosorbent assay and confirmed by using immunofluorescent antibody testing. Overall seroprevalence for Coxiella burnetii was 3.1% (95% confidence interval [CI] = 2.1-4.3%) among 4,437 adults > or = 20 years of age. Coxiella burnetii age-adjusted antibody prevalence was higher for men than for women (3.8%, 95% CI = 2.7-5.2% versus 2.5%, 95% CI = 1.5-3.7%, respectively, P < 0.05). Mexican Americans had a significantly higher antibody prevalence (7.4%, 95% CI = 6.6-8.3%) than either non-Hispanic whites (2.8%, 95% CI = 1.7-4.3%) or non-Hispanic blacks (1.3%, 95% CI = 0.6-2.5%) (P < 0.001). Multivariate analysis showed that the risk for Q fever antibody positivity increased with age and was higher among persons who were foreign-born, male, and living in poverty. These findings indicate that the national seroprevalence of Q fever in the United States is higher than expected on the basis of case numbers reported to the Centers for Disease Control and Prevention from state health departments. Potential differences in risk for exposure by race/ethnicity warrant further study.

OBJECTIVE: To monitor trends in HIV seroprevalence in the United States, HIV testing was included in the National Health and Nutrition Examination Survey (NHANES) conducted from 1999 to 2006. METHODS: From 1999 to 2006, 11,928 participants aged 18-49 years were tested for HIV antibody. Prevalence estimates were weighted to account for oversampling and nonresponse. RESULTS: There were 67 HIV antibody-reactive individuals for a seroprevalence of 0.5% [95% confidence interval (CI) 0.3-0.6]. In the only age subgroup directly comparable between surveys (18-39 years), HIV seroprevalence remained constant from NHANES III (1988-1994) to NHANES 1999-2002 and 2003-2006. In NHANES 1999-2006, non-Hispanic blacks had significantly higher HIV seroprevalence (2.0%, 95% CI 1.5-2.7) compared with individuals in all other race/ethnic groups combined. Seroprevalence was also higher in each race/ethnic group among men who have sex with men (9.4% 95% CI 5.0-17.1), among persons who had detectable antibody to herpes simplex type-two (1.9% 95% CI 1.4-2.8), among those who had 50 or more lifetime sex partners (3.4%, 95% CI 1.7-6.7), and among those who never married (0.8%, 95% CI 0.5-1.3). CONCLUSIONS: In this household-based population, seroprevalence did not significantly change from NHANES III to NHANES 1999-2006. Non-Hispanic blacks had significantly higher prevalence of infection compared with other race/ethnic groups. Male-to-male sex and the presence of HSV-2 antibody were the strongest predictors of HIV infection.