A longitudinal cohort study of soil-transmitted helminth infections during the second year of life and associations with reduced long-term cognitive and verbal abilities
Open accessAbstract
BACKGROUND: Soil-transmitted helminth (STH) infection leads to malnutrition and anemia, and has been linked to impaired child development. Previous research on this topic is limited and mostly conducted in school-age children. The goal of this study was to determine the effect of the number of detected STH infections between one and two years of age on subsequent cognitive and verbal abilities, in a cohort of preschool children. METHODOLOGY/PRINCIPAL FINDINGS: A longitudinal cohort study was conducted in 880 children in Iquitos, Peru between September 2011 and July 2016. Children were recruited at one year of age and followed up at 18 months and then annually between two and five years of age. STH infection was measured with the Kato-Katz technique or the direct smear technique. Child development was measured with the Bayley Scales of Infant and Toddler Development-III at the one to three-year visits and with the Wechsler Preschool and Primary Scale of Intelligence-III at the four and five-year visits. Hierarchical multivariable linear regression models were used to account for the repeated outcome measures for each child and Bayesian latent class analysis was used to adjust for STH misclassification. Children found infected with any STH infection between one and two years of age had lower cognitive scores between two and five years of age (between group score differences (95% credible intervals) for infected once, and infected two or three times, compared to never infected: -4.31 (-10.64, -0.14) and -3.70 (-10.11, -0.11), respectively). Similar results were found for Ascaris infection and for verbal scores. CONCLUSIONS/SIGNIFICANCE: An association was found between having been infected with Ascaris or any STH between one and two years of age and lower cognitive and verbal abilities later in childhood. These results suggest that targeting children for STH control as of one year of age is particularly important.
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In a study in Peru, infection with soil-transmitted helminths (STH) has been shown to reduce verbal IQ scores.
“In a study in Peru, infection with soil-transmitted helminths (STH) has been shown to reduce verbal IQ scores [4].”
From Assessing early child development and its association with stunting and schistosome infections in rural Zimbabwean children using the Griffiths Scales of Child Development (2021) · cites this paper as [4]
The Discussion reports that children in the Peruvian cohort who had STH infection between ages one and two had lower verbal scores at ages two to five. The Methods (Outcome ascertainment; page unavailable) identify verbal IQ as the measure used at ages four and five. But the paper describes an association in a cohort study, not proof that infection caused the reduction implied by “has been shown to reduce.” (LLM, conf=0.86)
Experimental — accuracy not yet measuredDetrimental effects of helminth infections (both STH and schistosomes) have been previously reported.
“Whilst the detrimental effects of helminth infections (both STH [4] and schistosomes [7]) have been previously reported”
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- Authors
- Blouin, B., Casapia, M., Joseph, L., & Gyorkos, T. W.
- Affiliations
- McGill University Health Centre (CA)
- Corresponding author
- Gyorkos, Theresa W.
- Venue
- PLoS neglected tropical diseases
- Publisher
- Public Library of Science (PLoS)
- Published
- 2018-07-27
- Volume
- 12
- Issue
- 7
- Pages
- e0006688
- ISSN
- 1935-2727 (ISSN-L)
- 1935-2735
- PMC
- PMC6082574
- OpenAlex
- W2884291400
- Cited by
- 30
- References
- 39
- Citations by year
- 2026: 3 · 2025: 2 · 2024: 3 · 2023: 3 · 2022: 8 · 2021: 3 · 2020: 2 · 2019: 6
- FWCI
- 2.22
- Type
- journal article
- Language
- en
- Update notices
- new_version (2018-08-08)
- Open access
- gold
- doi.org
- Licence
- Locations
- PLoS neglected tropical diseases (publishedVersion, cc-by)
- Europe PMC (PubMed Central) (publishedVersion, cc-by)
- PubMed Central (publishedVersion, cc-by)
- PubMed (publishedVersion)
- DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
- Figshare (submittedVersion, cc-by)
- Funders
- Thrasher Research Fund (US) (02832-2)
- Canadian Institutes for Health Research (MOP-110969)
- National Institute of Allergy and Infectious Diseases (P50AI098574)
- Topics
- Life Sciences › Immunology and Microbiology › Parasitology › Parasites and Host Interactions
- Health Sciences › Nursing › Nutrition and Dietetics › Child Nutrition and Water Access
- Life Sciences › Agricultural and Biological Sciences › Insect Science › Mollusks and Parasites Studies
- Keywords
- soil-transmitted helminths, Ascaris lumbricoides, early childhood infection, cognitive development, verbal ability, preschool children, helminth control, Bayley Scales of Infant and Toddler Development, Wechsler Preschool and Primary Scale of Intelligence, Iquitos
- MeSH terms
- Animals, Child Development, Child, Preschool, Cognition, Female, Helminthiasis, Helminths, Humans, Infant, Longitudinal Studies, Male, Peru, Soil, Speech, Verbal Learning, Cohort Studies
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