Abstract
BackgroundAlthough Toxocara spp. infection has a worldwide distribution, to our knowledge, no data from birth cohorts have been reported in published studies on the potential for congenital transmission and determinants of infection in early childhood.MethodsWe followed 290 mother-infant pairs from birth to 5 years of age through periodic collection of data and samples at birth, 7 and 13 months and 2, 3 and 5 years of age. Data on potential risk factors and confounders were collected by maternal questionnaire. Blood for plasma was collected from the mother at time of birth and periodically from the child for detection of anti-Toxocara spp. immunoglobulin G (IgG) antibodies using a Toxocara canis larval excretory-secretory antigen-based enzyme-linked immunosorbent assay. Stool samples were collected from the mother around the time of birth and periodically from the child for microscopic detection of soil-transmitted helminths (STH). Associations between potential risk factors and Toxocara spp. seroprevalence and seroconversion were estimated using multivariable logistic regression and generalized estimating equations.ResultsToxocara spp. seroprevalence was 80.7% in mothers and in children was 0%, 9.3%, 48.4%, 64.9%, and 80.9% at 7 months, 13 months, 2, 3 and 5 years, respectively. Risk factors significantly associated with increases in seroprevalence over the first 5 years of life in multivariable analyses were age [Odds ratio (OR) 2.06, 95% confidence interval (CI) 1.39–2.27, P < 0001], male sex (female vs. male: OR 0.66, 95% CI 0.48–0.89, P = 0.006), maternal ethnicity (non-Afro vs. Afro-Ecuadorian: OR 0.65, 95% CI 0.47–0.91, P = 0.011), lower maternal educational and socioeconomic level, and childhood STH (OR 2.29, 95% CI 1.51–3.47, P < 0.001). Seroconversion rates for infection were greatest at 2 years of age (3.8%/month). Factors associated significantly with seroconversion at 2, 3 or 5 years were childhood STH infection, male sex, and more frequent domestic cat exposure.ConclusionsOur data, from an area of high Toxocara spp. endemicity, indicate no congenital transmission but high rates of seroconversion after 13 months of age reaching maternal levels of seroprevalence by 5 years of age. Factors associated with seroprevalence and seroconversion included STH infections, domestic cats, maternal ethnicity, male sex, STH infections, and markers of greater poverty.Graphical
Highlights
Toxocara spp. infection has a worldwide distribution, to our knowledge, no data from birth cohorts have been reported in published studies on the potential for congenital transmission and determinants of infection in early childhood
Study design The present study was nested within a larger birth cohort, the ECUAVIDA cohort, of 2404 mother-child pairs followed from birth to 5 years of age in the district of Quinindé in Esmeraldas Province, Ecuador, that has been described in detail elsewhere [5]
Plasma samples were analysed for 290 mothers and their children at birth, for 267 (92.1%) samples collected at 7 months, and for 267 (92.1%), 261 (90.0%), 268 (92.4%), and 247 (85.2%) samples collected at 13 months, and 2, 3 and 5 years, respectively
Summary
Toxocara spp. infection has a worldwide distribution, to our knowledge, no data from birth cohorts have been reported in published studies on the potential for congenital transmission and determinants of infection in early childhood. Toxocariasis is a common parasitic disease with a worldwide distribution [1]. Humans and several animals are paratenic hosts, infected through accidental ingestion of embryonated eggs through contaminated water, soil, and food. Toxocara spp. cannot develop in humans beyond the larval stage, larvae may survive migrating in tissues for months or years [1]. While most human infections are asymptomatic, infection may have severe clinical consequences causing visceral larval migrans or infections of the central nervous system including the eyes [1]. Disease severity is considered to depend on larval burden and host inflammatory response to invasive larvae [1]
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