In utero exposure to malaria is associated with metabolic traits in adolescence: The Agogo 2000 birth cohort study

Hypertension among adolescents in sub-Saharan Africa: a systematic review

Introduction

Hypertension (HTN) among adolescents is common in high-income countries, and leads to increased premature cardiovascular diseases (CVD). In sub-Saharan Africa (SSA), the prevalence of HTN among adolescents, associated risk factors and CVD complications are not well-described. Such data is needed for planning public health programs to prevent premature CVD in SSA.

Methods

We systematically searched 5 databases (MEDLINE, Embase, Google Scholar, Web of Science, and African Index Medicus) from their establishment to December 2021. Key search terms were: adolescent, arterial hypertension, and names of the 48 countries in SSA. We used Covidence® to manage the search results. The review was registered in the Open Science Framework (OSF) https://osf.io/p5sbt/.

Results

We identified 4,008 articles out of which we screened 3,088 abstracts, and reviewed 583 full-text articles. We finally included 92 articles that were published between 1968 to December 2021. The majority were cross-sectional studies (80%) and conducted in school settings (78%). The risk of bias was low for 59 studies (64.1%), moderate for 29 studies (31.5%), and high for 4 studies (4.3%). Overall, the prevalence of HTN varied widely from 0.18% to 34.0% with a median (IQR) of 5.5% (3.1%, 11.1%). It was relatively higher in studies using automated blood pressure (BP) devices, and in studies defining HTN using thresholds based on percentile BP distribution for one's height, age, and sex. In addition, the prevalence of HTN was significantly higher in studies from Southern Africa region of SSA and positively correlated with the year of publication. Across studies, traditional risk factors such as age, sex, body mass index, and physical inactivity, were commonly found to be associated with HTN. In contrast, non-traditional risk factors related to poverty and tropical diseases were rarely assessed. Only three studies investigated the CVD complications related to HTN in the study population.

Conclusion

The prevalence of HTN among adolescents in SSA is high indicating that this is a major health problem. Data on non-traditional risk factors and complications are scarce. Longitudinal studies are needed to clearly define the rates, causes, and complications of HTN.

Systematic Review Registration

https://osf.io/p5sbt/, identifier (10.17605/OSF.IO/P5SBT).

Influence of placental and peripheral malaria exposure in fetal life on cardiometabolic traits in adult offspring

INTRODUCTION

Fetal malaria exposure may lead to intrauterine growth restriction and increase the risk of developing diabetes and cardiovascular diseases in adulthood. We investigated the extent to which fetal peripheral and placental malaria exposure impacts insulin sensitivity and secretion, body composition and cardiometabolic health 20 years after in utero malaria exposure.

RESEARCH DESIGN AND METHODS

We traced 101 men and women in Muheza district, Tanga region whose mothers participated in a malaria chemosuppression during a pregnancy study in 1989-1992. All potential participants were screened for malaria, hepatitis B and HIV to ascertain study eligibility. Seventy-six individuals (44 men, 32 women) were included in this cohort study. The participants underwent a thorough clinical examination including anthropometric measurements, ultrasound scanning for abdominal fat distribution, blood pressure, 75 g oral glucose tolerance test, an intravenous glucose tolerance test followed by a hyperinsulinemic euglycemic clamp and a submaximal exercise test.

RESULTS

Offspring exposed to placental malaria during pregnancy had significantly higher 30-minute plasma post-glucose load levels, but no significant difference in peripheral insulin resistance, insulin secretion or other cardiometabolic traits compared with non-exposed individuals.

CONCLUSIONS

Using the state-of-the-art euglycemic clamp technique, we were unable to prove our a priori primary hypothesis of peripheral insulin resistance in young adult offspring of pregnancies affected by malaria. However, the subtle elevations of plasma glucose might represent an early risk marker for later development of type 2 diabetes if combined with aging and a more obesogenic living environment.

Fasting blood glucose in a Ghanaian adult is causally affected by malaria parasite load: a mechanistic case study using convergent cross mapping

BACKGROUND

Adults with diabetes mellitus (DM) in malaria-endemic areas might be more susceptible to Plasmodium infection than healthy individuals. Herein, the study was aimed at verifying the hypothesis that increased fasting blood glucose (FBG) promotes parasite growth as reflected by increased parasite density.

METHODS

Seven adults without DM were recruited in rural Ghana to determine the relationships between FBG and malaria parasite load. Socio-economic data were recorded in questionnaire-based interviews. Over a period of 6 weeks, FBG and Plasmodium sp. Infection were measured in peripheral blood samples photometrically and by polymerase chain reaction (PCR)-assays, respectively. Daily physical activity and weather data were documented via smartphone recording. For the complex natural systems of homeostatic glucose control and Plasmodium sp. life cycle, empirical dynamic modelling was applied.

RESULTS

At baseline, four men and three women (median age, 33 years; interquartile range, 30-48) showed a median FBG of 5.5 (5.1-6.0 mmol/L); one participant had an asymptomatic Plasmodium sp. infection (parasite density: 240/µL). In this participant, convergent cross mapping (CCM) for 34 consecutive days, showed that FBG was causally affected by parasite density (p < 0.02), while the reciprocal relationship was not discernible (p > 0.05). Additionally, daily ambient temperature affected parasite density (p < 0.01).

CONCLUSION

In this study population living in a malaria-endemic area, time series analyses were successfully piloted for the relationships between FBG and Plasmodium sp. density. Longer observation periods and larger samples are required to confirm these findings and determine the direction of causality.

Epidemiological links between malaria parasitaemia and hypertension: findings from a population-based survey in rural Côte d'Ivoire

Background:

Although potential links between malaria parasitaemia and hypertension have been hypothesized, there is paucity of epidemiologic evidence on this link. We investigated in a population-based survey, the association between malaria parasitaemia and hypertension in Ivorian adults.

Methods:

We estimated the adjusted odds ratios (OR) and 95% confidence intervals (CI) of hypertension in relation to malaria parasitaemia using multinomial regression, in 997 randomly selected adults in the ‘Côte d’Ivoire Dual Burden of Disease Study’ (CoDuBu), in south-central Côte d’Ivoire. We defined malaria parasitaemia as a positive rapid diagnostic test or identification of Plasmodium spp. on microscopy. Using the mean of the last two of three blood pressure (BP) measurements and questionnaire data, we defined hypertension as SBP at least 140 mmHg or DBP at least 90 mmHg or clinician-diagnosed hypertension.

Results:

Prevalence of malaria parasitaemia and hypertension were 10 and 22%, respectively. Malaria parasitaemia was negatively associated with hypertension in participants with body temperature 36.5 °C or less [OR 0.23 (95% CI 0.06–0.84)]. Contrastingly, microscopic malaria parasitaemia showed positive associations with hypertension in participants with elevated body temperature [>36.5 °C; OR: 2.93 (95% CI 0.94–9.14)]. Participants having microscopic malaria parasitaemia with elevated body temperature had three-fold higher odds of hypertension [OR: 3.37 (95% CI 1.12–10.0)] than malaria parasitaemia-negatives with lower body temperature.

Conclusion:

Malaria parasitaemia and hypertension are prevalent and seemingly linked comorbidities in African settings. This link may depend on malaria parasitaemia symptomaticity/latency where individuals with more latent/asymptomatic malaria parasitaemia have lower risk of hypertension and those with more acute/symptomatic malaria parasitaemia have a tendency toward higher BP. The cross-sectional nature of the study limited the distinction of short-term BP elevation (interim pathophysiological stress) from hypertension development. Future longitudinal studies considering malaria/hypertension phenotypes and host molecular variations are needed to clarify involved biological mechanisms, toward comorbidity management.

SNP rs6564851 in the BCO1 Gene Is Associated with Varying Provitamin a Plasma Concentrations but Not with Retinol Concentrations among Adolescents from Rural Ghana

In sub-Saharan Africa, vitamin A deficiency constitutes a severe health problem despite various supplementation and food fortification programs. Given that the intake of preformed vitamin A from animal products remains low in these countries, an efficient metabolization of plant-based provitamin A carotenoids is essential. Previously, adolescents in rural Ghana have shown high total plasma carotenoid concentrations, while 36% had a vitamin A deficiency (defined as plasma retinol < 0.7 µmol/L). Hence, the aim of this cross-sectional study was to identify the relationships between variants in the β-carotene 15,15'-oxygenase (BCO1) gene and plasma carotenoid concentrations among 189 15-year-old girls and boys in rural Ghana. BCO1 rs6564851, rs7500996, rs10048138 and PKD1L2 rs6420424, and rs8044334 were typed, and carotenoid concentrations were compared among the different genotypes. G allele carriers of rs6564851 (53%) showed higher plasma carotenoid concentrations than T allele carriers (median (interquartile range): 3.07 (2.17-4.02) vs. 2.59 (2.21-3.50) µmol/L, p-value = 0.0424). This was not explained by differences in socio-demographic or dietary factors. In contrast, no differences in plasma retinol concentrations were observed between these genotypes. Pending verification in independent populations, the low conversion efficiency of provitamin A carotenoids among rs6564851 G allele carriers may undermine existing fortification and supplementation programs to improve the vitamin A status in sub-Saharan Africa.

Developmental plasticity as adaptation: adjusting to the external environment under the imprint of maternal capital

Plasticity is assumed to enable beneficial adjustment to the environment. In this context, developmental plasticity is generally approached within a two-stage framework, whereby adjustments to ecological cues in stage 1 are exposed to selection in stage 2. This conceptual approach may have limitations, because in species providing parental investment, particularly placental mammals such as humans, initial adjustments are not to the environment directly, but rather to the niche generated by parental phenotype (in mammals, primarily that of the mother). Only as maternal investment is withdrawn is the developing organism exposed directly to prevailing ecological conditions. A three-stage model may therefore be preferable, where developmental trajectory first adjusts to maternal investment, then to the external environment. Each offspring experiences a trade-off, benefitting from maternal investment during the most vulnerable stages of development, at the cost of exposure to investment strategies that maximize maternal fitness. Maternal life-history trade-offs impact the magnitude and schedule of her investment in her offspring, generating lifelong effects on traits related to health outcomes. Understanding the imprint of maternal capital on offspring is particularly important in species demonstrating social hierarchy. Interventions targeting maternal capital might offer new opportunities to improve health outcomes of both mother and offspring. This article is part of the theme issue 'Developing differences: early-life effects and evolutionary medicine'.

Asymptomatic Plasmodium infection and glycemic control in adults: Results from a population-based survey in south-central Côte d'Ivoire

AIMS

We investigated the cross-sectional associations of Plasmodium infection (PI) with fasting glucose (FG) and glycated hemoglobin (HbA1c) in malaria-endemic south-central Côte d'Ivoire.

METHODS

We studied 979 participants (non-pregnant; no treated diabetes; 51% males; 18-87 years) of the Côte d'Ivoire Dual Burden of Disease study. Fasting venous blood was obtained for PI, FG, and HbA1c assessment. We defined PI as a positive malaria rapid diagnostic test (RDT) or microscopic identification of Plasmodium species. We applied multivariable linear regressions to assess beta coefficients (β) and 95% confidence intervals (CIs) of PI positivity for FG and HbA1c independent of diabetes risk factors.

RESULTS

Prevalence of PI was 10.1% (5.5% microscopy; 9.7% RDT) without clinical fever. Prevalence of FG-based prediabetes (45.8%) and diabetes (3.6%) were considerably higher than HbA1c-based values (2.7% and 0.7%, respectively). PI was independently associated with FG among participants with higher body temperature (β 0.34, 95% CI 0.06-0.63, p_{heterogeneity} = 0.028), or family history of diabetes (β 0.88, 95% CI 0.28-1.47, p_{heterogeneity} = 0.009). Similar patterns observed with HbA1c were obliterated on accounting for FG. We also observed consistent associations with parasite density.

CONCLUSIONS

FG-based diabetes diagnosis in the presence of asymptomatic PI may misclassify or overestimate diabetes burden in malaria-endemic settings. Longitudinal studies are needed to confirm these findings and determine the risk for diabetes.

Intrauterine programming of obesity and type 2 diabetes

The type 2 diabetes epidemic and one of its predisposing factors, obesity, are major influences on global health and economic burden. It is accepted that genetics and the current environment contribute to this epidemic; however, in the last two decades, both human and animal studies have consolidated considerable evidence supporting the 'developmental programming' of these conditions, specifically by the intrauterine environment. Here, we review the various in utero exposures that are linked to offspring obesity and diabetes in later life, including epidemiological insights gained from natural historical events, such as the Dutch Hunger Winter, the Chinese famine and the more recent Quebec Ice Storm. We also describe the effects of gestational exposure to endocrine disruptors, maternal infection and smoking to the fetus in relation to metabolic programming. Causal evidence from animal studies, motivated by human observations, is also discussed, as well as some of the proposed underlying molecular mechanisms for developmental programming of obesity and type 2 diabetes, including epigenetics (e.g. DNA methylation and histone modifications) and microRNA interactions. Finally, we examine the effects of non-pharmacological interventions, such as improving maternal dietary habits and/or increasing physical activity, on the offspring epigenome and metabolic outcomes.