Low-level Plasmodium vivax exposure, maternal antibodies, and anemia in early childhood: Population-based birth cohort study in Amazonian Brazil

Hypertensive disorders of pregnancy in Western Brazilian Amazon: Associated factors and neonatal outcomes

OBJECTIVE

Hypertensive disorders of pregnancy (HDP) are responsible for several maternal and fetal complications. This study investigated the occurrence of HDP, associated factors, and neonatal complications in women living in the Western Brazilian Amazon.

METHODS

This is a population-based cross-sectional study with 1521 mother-child pairs enrolled in the Maternal and Child Health and Nutrition in Acre birth cohort (MINA-Brazil study). All parturients with HDP (registered in the medical records) were identified. Crude and adjusted prevalence ratios were calculated in Poisson regression models with robust variance.

RESULTS

The prevalence of HDP was 11.0% (95% CI: 9.5-12.7). Factors associated with the prevalence of HDP were maternal age ≥ 35 years (PR: 1.9; 95% CI: 1.3-3.0), primigravida status (PR: 2.0; 95% CI: 1.5-2.7), pre-pregnancy obesity (PR: 2.7; 95% CI: 1.9-4.0), higher gestational weight gain (highest quartile RP: 2.5; 95% CI: 1.6-3.8), chronic hypertension (RP: 3.6; 95% CI: 2.7-4.9), and diabetes in pregnancy (RP: 1.9; 95% CI: 1.1-3.2). HDP was associated with risk for caesarean delivery (PR: 1.8; 95% CI: 1.6-2.0) and prematurity (PR: 2.0; 95% CI: 1.3-3.2). Gestational malaria was not associated with HDP in Amazonian pregnant women.

CONCLUSIONS

Evaluating risk factors before pregnancy and during the prenatal period is essential for reducing adverse maternal and neonatal outcomes.

Prevalence and correlates of childhood anemia in the MINA-Brazil birth cohort study

OBJECTIVE

This study aimed to describe the prevalence and predictors of childhood anemia in an Amazonian population-based birth cohort study.

METHODS

Prevalence of maternal anemia was estimated at delivery (hemoglobin [Hb] concentration < 110 g/L) in women participating in the MINA-Brazil birth cohort study and in their children, examined at ages one, two (Hb < 110 g/L), and five (Hb < 115 g/L). Moreover, ferritin, soluble transferrin receptor, and C-reactive protein concentrations were measured in mothers at delivery and in their 1- and 2-year-old children to estimate the prevalence of iron deficiency and its contribution to anemia, while adjusting for potential confounders by multiple Poisson regression analysis (adjusted relative risk [RRa]).

RESULTS

The prevalence 95% confidence interval (CI) of maternal anemia, iron deficiency, and iron-deficiency anemia at delivery were 17.3% (14.0-21.0%), 42.6% (38.0-47.2%), and 8.7% (6.3-11.6)%, respectively (n = 462). At one year of age (n = 646), 42.2% (38.7-45.8%) of the study children were anemic, 38.4% (34.6-42.3%) were iron-deficient, and 26.3 (23.0-29.9) had iron-deficiency anemia. At two years of age (n = 761), these values decreased to 12.8% (10.6-15.2%), 18.1% (15.5-21.1%), and 4.1% (2.8-5.7%), respectively; at five years of age (n = 655), 5.2% (3.6-7.2%) were anemic. Iron deficiency (RRa = 2.19; 95%CI: 1.84-2.60) and consumption of ultra-processed foods (UPF) (RRa = 1.56; 95%CI: 1.14-2.13) were significant contributors to anemia at 1 year, after adjusting for maternal schooling. At 2 years, anemia was significantly associated with maternal anemia at delivery (RRa: 1.67; 95%CI: 1.17-2.39), malaria since birth (2.25; 1.30-3.87), and iron deficiency (2.15; 1.47-3.15), after adjusting for children's age and household wealth index.

CONCLUSIONS

Anemia continues to be highly prevalent during pregnancy and early childhood in the Amazon. Public health policies should address iron deficiency, UPF intake, maternal anemia, and malaria to prevent and treat anemia in Amazonian children.

Adolescent pregnancy in Cruzeiro do Sul, Acre, Brazil: socioeconomic characteristics, prenatal and obstetric care

The present study aimed to investigate the socioeconomic and obstetric characteristics of adolescent mothers and the complications they cause to maternal and neonatal health. This baseline data analysis of the MINA-Brazil birth cohort was conducted in the municipality of Cruzeiro do Sul, state of Acre, Brazil. The chi-square test was used to compare characteristics of adolescent and adult postpartum women, and multiple Poisson regression models with robust variance were used to assess associated factors. Among the postpartum women, 26.2% (95%CI: 24.0-28.4) were adolescents. Factors associated with childbirth in adolescence included: nine years or less of schooling (adjPR:1.36; 95%CI: 1.14-1.61), belongs to the lowest quartiles of the wealth index (1st quartile: adjPR:1.40; 95%CI: 1.08-1.80) (2nd quartile: adjPR:1.37; 95%CI: 1.08-1.74), primigravidae (adjPR:3.69; 95%CI: 2.98-4.57), low pre-pregnancy BMI (adjPR:1.28; CI95%: 1.04-1.57), urinary tract infection during pregnancy (adjPR:1.25; CI95%: 1.07-1.46) and less than six prenatal consultations (adjPR:1.42; 95%CI: 1.21-1.66). Poverty, little schooling, primigravidae, low pre-pregnancy BMI, urinary tract infection during pregnancy and few prenatal consultations were associated with childbirth during adolescence in a municipality in the Northern region of Brazil.

Individual variation in Plasmodium vivax malaria risk: Are repeatedly infected people just unlucky?

Extensive research has examined why some people have frequent Plasmodium falciparum malaria episodes in sub-Saharan Africa while others remain free of disease most of the time. In contrast, malaria risk heterogeneity remains little studied in regions where P. vivax is the dominant species. Are repeatedly infected people in vivax malaria settings such as the Amazon just unlucky? Here, we briefly review evidence that human genetic polymorphism and acquired immunity after repeated exposure to parasites can modulate the risk of P. vivax infection and disease in predictable ways. One-fifth of the hosts account for 80% or more of the community-wide vivax malaria burden and contribute disproportionally to onward transmission, representing a priority target of more intensive interventions to achieve malaria elimination. Importantly, high-risk individuals eventually develop clinical immunity, even in areas with very low or residual malaria transmission, and may constitute a large but silent parasite reservoir.

Update on pathogenesis, management, and control of Plasmodium vivax

PURPOSE OF REVIEW

This is a review of Plasmodium vivax epidemiology, pathogenesis, disease presentation, treatment and innovations in control and elimination. Here, we examine the recent literature and summarize new advances and ongoing challenges in the management of P. vivax .

RECENT FINDINGS

P. vivax has a complex life cycle in the human host which impacts disease severity and treatment regimens. There is increasing data for the presence of cryptic reservoirs in the spleen and bone marrow which may contribute to chronic vivax infections and possibly disease severity. Methods to map the geospatial epidemiology of P. vivax chloroquine resistance are advancing, and they will inform local treatment guidelines. P. vivax treatment requires an 8-aminoquinoline to eradicate the dormant liver stage. Evidence suggests that higher doses of 8-aminoquinolines may be needed for radical cure of tropical frequent-relapsing strains.

SUMMARY

P. vivax is a significant global health problem. There have been recent developments in understanding the complexity of P. vivax biology and optimization of antimalarial therapy. Studies toward the development of best practices for P. vivax control and elimination programs are ongoing.

Prolonged Breastfeeding and the Risk of Plasmodium vivax Infection and Clinical Malaria in Early Childhood: A Birth Cohort Study

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.

Pregnancy and malaria: the perfect storm

PURPOSE OF REVIEW

Malaria in pregnancy continues to exert a toll on pregnant women and their offspring.

RECENT FINDINGS

The burden of Plasmodium falciparum infection is especially large in Africa, and new data show lasting effects of maternal infection on the infant's neurocognitive development. Elsewhere, P. vivax infection causes relapsing infections that are challenging to prevent. Infection in first trimester of pregnancy is an area of increasing focus, and its adverse effects on pregnancy outcome are increasingly recognised. First-trimester infection is common and frequently acquired prior to conception. Although newer rapid diagnostic tests still have limited sensitivity, they may be useful in detection of early pregnancy malaria for treatment. Artemisinin-based combination therapies are efficacious in later pregnancy but have yet to be recommended in first trimester because of limited safety data. In Africa, intermittent preventive treatment in pregnancy (IPTp) with monthly sulfadoxine-pyrimethamine improves pregnancy outcomes, but sulfadoxine-pyrimethamine resistance is worsening. The alternative, IPTp with dihydroartemisinin-piperaquine, has greater antimalarial efficacy, but does not appear to improve pregnancy outcomes, because sulfadoxine-pyrimethamine has poorly understood nonmalarial benefits on birthweight.

SUMMARY

Novel IPTp regimens must be combined with interventions to strengthen protection from malaria infection acquired before and in early pregnancy.