A Birth Cohort Study

Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.BACKGROUND: Relatively few Amazonian infants have clinical malaria diagnosed, treated and notified before their first birthday, either because they are little exposed to an infection or remain asymptomatic once infected. Here we measure the proportion of children who have experienced Plasmodium vivax infection and malaria by 2 years of age in the main transmission hotspot of Amazonian Brazil. METHODS: We measured IgG antibodies to 3 blood-stage P. vivax antigens at the 1- and 2-year follow-up assessment of 435 participants in a population-based birth cohort. Children's malaria case notifications were retrieved from the electronic database of the Ministry of Health. We used multiple Poisson regression models to identify predictors of serologically proven P. vivax infection and clinical vivax malaria during the first 2 years of life. RESULTS: Overall, 23 [5.3%; 95% confidence interval (CI): 3.5-7.8%) children had antibodies to ≥2 antigens detected during at least one follow-up assessment, consistent with past P. vivax infection(s). Fifteen (3.4%; 95% CI: 2.1-5.6%) children had clinical vivax episodes notified during the first 2 years of life; 7 of them were seronegative. We estimate that half of the infections remained unnotified. Children born to women who experienced P. vivax infection during pregnancy were more likely to be infected and develop clinical vivax malaria, while those breast-fed for ≥12 months had their risk of being P. vivax-seropositive (which we take as evidence of blood-stage P. vivax infection during the first 2 years of life) decreased by 79.8% (95% CI: 69.3-86.7%). CONCLUSION: P. vivax infections in early childhood are underreported in the Amazon, are associated with anemia at 2 years of age, and appear to be partially prevented by prolonged breastfeeding.publishersversionepub_ahead_of_prin

Early determinants of linear growth and weight attained in the first year of life in a malaria endemic region.

We investigated linear growth and weight attained among 772 children at 10-15 months of age in the first population-based birth cohort in the Brazilian Amazon. Sociodemographic, maternal and birth characteristics were collected in interviews soon after birth at baseline. Anthropometric evaluation was conducted at 10-15 months. Multiple linear regression models were fitted for length-for-age (LAZ) and body mass index (BMI)-for-age Z scores (BAZ), considering a hierarchical conceptual framework with determinants at distal, intermediate and proximal levels, with adjustment for the child's sex and age. Mean LAZ and BAZ were 0.31 (SD: 1.13) and 0.35 (SD: 1.06), respectively. Overall, 2.2% of children were stunted and 6.6% overweight. Among socioeconomic factors, household wealth index was positively associated with LAZ (p for trend = 0.01), while children whose families received assistance from the Bolsa Família conditional cash transfer program were 0.16 Z score thinner (95% CI: -0.31, -0.00). Maternal height and BMI were positively associated with both LAZ and BAZ at 10-15 months of age (p for trend <0.001). Child's size at birth was positively related with LAZ (p<0.001 for both birth weight and length). BAZ was 0.34 (95% CI: 0.24, 0.44) higher, but 0.11 lower (95% CI: -0.21, -0.02), for each increase in 1 Z score of birth weight and length, respectively. Children with at least one reported malaria episode within the first year of life were 0.58 (95% CI: -1.05, -0.11) Z score shorter. Socioeconomic and intergenerational factors were consistently associated with LAZ and BAZ at 10-15 months of age. The occurrence of malaria was detrimental to linear growth. In a malaria endemic region, reduction of inequalities and disease burden over the first 1,000 days of life is essential for taking advantage of a critical window of opportunity that can redirect child growth trajectories toward better health and nutrition conditions in the long term