Toxocara infection in the United States: the relevance of poverty, geography and demography as risk factors, and implications for estimating county prevalence.
OBJECTIVE
To estimate Toxocara infection rates by age, gender and ethnicity for US counties using data from the National Health and Nutrition Examination Survey (NHANES).


METHODS
After initial analysis to account for missing data, a binary regression model is applied to obtain relative risks of Toxocara infection for 20,396 survey subjects. The regression incorporates interplay between demographic attributes (age, ethnicity and gender), family poverty and geographic context (region, metropolitan status). Prevalence estimates for counties are then made, distinguishing between subpopulations in poverty and not in poverty.


RESULTS
Even after allowing for elevated infection risk associated with poverty, seropositivity is elevated among Black non-Hispanics and other ethnic groups. There are also distinct effects of region. When regression results are translated into county prevalence estimates, the main influences on variation in county rates are percentages of non-Hispanic Blacks and county poverty.


CONCLUSIONS
For targeting prevention it is important to assess implications of national survey data for small area prevalence. Using data from NHANES, the study confirms that both individual level risk factors and geographic contextual factors affect chances of Toxocara infection.
Congdon
Peter
P
Department of Geography, Center for Statistics, Queen Mary University of London, London, E1 4NS, UK. p.congdon@qmul.ac.uk
Lloyd
Patsy
P
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood*; D001499:Bayes Theorem; D002648:Child; D005006:Ethnicity; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D011203:Poverty; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D012737:Sex Factors; D014119:Toxocara / Q000276:immunology; D014120:Toxocariasis / Q000453:epidemiology*; D014481:United States / Q000453:epidemiology; D055815:Young Adult
D000909:Antibodies, Helminth