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Toxocara canis infection of children: epidemiologic and neuropsychologic findings
Insights
Toxocara canis infection is common in urban children, affecting over 5% of males and females. This parasitic infection may be linked to negative effects on children's neuropsychological development.
Area of Science:
- Environmental Health
- Infectious Diseases
- Pediatrics
Background:
- Toxocara canis infection is a widespread zoonotic disease.
- Urban environments may present unique risks for parasitic infections in children.
Purpose of the Study:
- To investigate the prevalence of Toxocara canis infection in New York City children.
- To explore the association between Toxocara canis infection and lead exposure.
- To examine potential neuropsychological effects of Toxocara canis infection in children.
Main Methods:
- Enzyme-linked immunosorbent assay (ELISA) was used to detect Toxocara canis antibodies in sera from 4,652 children.
- Case-control study matching seropositive children with seronegative controls on age, sex, screening time, and lead exposure levels.
- Logistic regression analysis was employed to determine relative risks for associated factors.
Main Results:
- T. canis seropositivity was 5.7% in males and 5.1% in females.
- A positive correlation was observed between T. canis antibody titers and lead exposure.
- Geophagia and having puppies in the home were significantly associated with increased risk of infection.
Conclusions:
- Toxocara canis infection is prevalent in urban children.
- Infection is associated with increased eosinophil counts, immunoglobulin E, and anti-hemagglutinin-A titers.
- Toxocara canis infection may be linked to subtle deficits in neuropsychological test performance.
Abstract:
Sera from 4,652 children whose blood was submitted to the New York City Department of Health for lead analysis were tested for antibodies to Toxocara canis using an enzyme-linked immunosorbent assay (ELISA). Standardized to the age distribution of the study population, T. canis seropositivity (inverse titers greater than or equal to 16) was 5.7 per cent in males and 5.1 per cent in females. T. canis antibody titers and lead exposures as measured by Centers for Disease Control lead classes were positively correlated. Children who were seropositive to T. canis (cases) were compared to seronegatives (controls) matched on age (+/- 6 months), sex, time-of-screening (+/- 3 months) and CDC lead class. Logistic regression analysis of 155 case-control pairs demonstrated elevated relative risks (RRs) for geophagia (RR = 3.14; 95% CI = 1.75, 5.64) and having had a litter of puppies in the home (RR = 5.22; 95% CI = 1.63, 16.71). Compared to controls, cases had increased eosinophil counts, serum immunoglobulin E concentrations, and anti-hemagglutinin-A titers. Small deficits in cases compared to controls were found in performance on several neuropsychological tests after adjustment for potential confounders including case-control differences in race, socioeconomic status, and current blood lead concentrations. The study thus confirmed that T. canis infection is common in urban children and suggested that infection may be associated with adverse neuropsychological effects.