Timing of malaria in pregnancy and impact on infant growth and morbidity: a cohort study in Uganda

Determinants of the optimal uptake of sulfadoxine-pyrimethamine doses for intermittent treatment of malaria in pregnancy in urban Nigeria

Malaria is a leading cause of maternal and child mortality in urban Nigeria. Intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-SP) during pregnancy can prevent malaria but uptake is suboptimal. This cross-sectional study analyzed secondary data on 1159 urban Nigerian women from the 2015 Malaria Indicator Survey using descriptive statistics and logistic regression. The primary outcome was optimal IPTp-SP uptake (≥ 3 doses). 67% of women took any SP during pregnancy but only 39% took ≥ 3 IPTp-SP doses as recommended. Region and wealth index significantly predicted optimal IPTp-SP uptake while education did not. Women from lower-income regions in the urban areas were less likely to receive optimal IPTp-SP. Strategies to increase IPTp-SP uptake in urban Nigeria should target low-income regions and women of lower socioeconomic status. Logistic regression identified actionable factors for improving antenatal malaria prevention. Optimal IPTp-SP uptake remains suboptimal across urban Nigeria, threatening maternal and child health.

Pathways through which intermittent preventive treatment for malaria in pregnancy influences child growth faltering: a mediation analysis

Background

Intermittent preventive treatment for malaria in pregnancy (IPTp) can improve birth outcomes, but whether it confers benefits to postnatal growth is unclear. We investigated the effect of IPTp on infant growth in Uganda and its pathways of effects using causal mediation analyses.

Methods

We analyzed data from 633 infants born to mothers enrolled in a randomized trial of monthly IPTp with dihydroartemisinin-piperaquine (DP) vs sulfadoxine-pyrimethamine (SP) (NCT02793622). Weight and length were measured from 0-12 months of age. Using generalized linear models, we estimated effects of DP vs. SP on gravidity-stratified mean length-for-age (LAZ) and weight-for-length Z-scores (WLZ). We investigated mediation by placental malaria, gestational weight change, maternal anemia, maternal inflammation-related proteins, preterm birth, birth length, and birth weight. Mediation models adjusted for infant sex, gravidity, gestational age at enrollment, maternal age, maternal parasitemia at enrollment, education, and wealth.

Findings

SP increased LAZ by 0.18-0.28 Z from birth through age 4 months compared to DP, while DP increased WLZ by 0.11-0.28 Z from 2-8 months compared to SP among infants of multigravidae. We did not observe these differences among primigravida. Mediators of SP included increased birth weight and length and maternal stem cell factor at delivery. Mediators of DP included placental malaria and birth length, maternal IL-18, CDCP1, and CD6 at delivery.

Interpretation

In high malaria transmission settings, different IPTp regimens influenced infant growth among multigravidae through distinct pathways in the period of exclusive breastfeeding, when few other interventions are available.

Funding

Stanford Center for Innovation and Global Health, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bill & Melinda Gates Foundation.

Predictors of birth weight in pregnant women with malaria: a prospective cohort facility-based study in Webuye-Kenya

In sub-Saharan Africa, malaria, which remains a major public health burden, has a prevalence of 9 to 28% and malaria in pregnancy is associated with severe adverse outcomes for the mother and her baby. Here, we sought to determine the predictors of birth weight in a cohort of 140 women with malaria in pregnancy, who were recruited at the Webuye County hospital in Western Kenya. All study participants underwent malaria diagnosis through microscopic examination of blood smear samples and were grouped into the malaria-positive and malaria-negative groups. Both groups were followed up beginning at the first antenatal visit (March 2022) until delivery (December 2022) and various data, including demographic, parity, gravidity, socioeconomic, maternal and fetal outcomes were collected. Data analyses were done using SPSS version 27. Chi-square and Fisher's Exact tests were used for bivariate and relative risk analyses at a p-value of ≤0.05 (95%) confidence level. Most of the participants were aged 18-25 years, were primigravidas and married, had secondary school-level education, earned 20-30 thousand Kenya shillings, resided in rural areas, and were in the second trimester. There were 6 (4.6%) cases of low birth weight, 3 (4.5%) in the malaria-negative group and 3 (4.7%) in the malaria-positive group. During pregnancy, 41 (31.5%) were anaemic, 5 (3.8%) were HIV-positive, 5 (3.8%) had preeclampsia, and 2 (1.5%) had gestational diabetes. Our analyses show that confounding factors like anaemia, HIV, pre-eclampsia and gestational diabetes did not influence birthweight (p ≥ 0.923). The malaria-positive and malaria-negative groups did not differ significantly with regard to the low birth weight (relative risk: 0.999, 95% confidence interval: 0.926-1.077). Marital status, gestational age, and area of residence were associated with malaria p ≤ 0.001, ≤ 0.001 and 0.028 respectively. In both groups, 124 of the 140 deliveries had normal birth weights and of these 63 (95.4%, n = 70) were in the malaria-negative group, whereas 61 (95.3%, n = 70) belonged to the malaria-positive group.

Intestinal barrier disruption with Plasmodium falciparum infection in pregnancy and risk of preterm birth: a cohort study

BACKGROUND

Malaria in early pregnancy is a risk factor for preterm birth and is associated with sustained inflammation and dysregulated angiogenesis across gestation. This study investigated whether malaria is associated with increased gut leak and whether this contributes to systemic inflammation, altered angiogenesis, and preterm birth.

METHODS

We quantified plasma concentrations of gut leak markers, soluble CD14 (sCD14) and lipopolysaccharide binding protein (LBP) from 1339 HIV-negative pregnant Malawians at <24 weeks gestational age. We assessed the relationship of sCD14 and LBP concentrations with markers of inflammation, angiogenesis, and L-arginine bioavailability and compared them between participants with and without malaria, and with and without preterm birth.

FINDINGS

Plasma concentrations of sCD14 and LBP were significantly higher in participants with malaria and were associated with parasite burden (p <0.0001, both analyses and analytes). The odds ratio for preterm birth associated with one log sCD14 was 2.67 (1.33 to 5.35, p = 0.006) and 1.63 (1.07-2.47, p = 0.023) for LBP. Both gut leak analytes were positively associated with increases in proinflammatory cytokines CRP, sTNFR2, IL18-BP, CHI3L1 and Angptl3 (p <0.05, all analytes) and sCD14 was significantly associated with angiogenic proteins Angpt-2, sENG and the sFLT:PlGF ratio (p <0.05, all analytes). sCD14 was negatively associated with L-arginine bioavailability (p <0.001).

INTERPRETATION

Malaria in early pregnancy is associated with intestinal barrier dysfunction, which is linked to an increased risk of preterm birth.

FUNDING

Open Philanthropy, Canadian Institutes of Health Research, Canada Research Chair program, European and Developing Countries Clinical Trials Partnership, Bill & Melinda Gates Foundation.

Malaria in Pregnancy: Key Points for the Neonatologist

In malaria-endemic regions, infection with the malaria parasite Plasmodium during pregnancy has been identified as a key modifiable factor in preterm birth, the delivery of low-birthweight infants, and stillbirth. Compared with their nonpregnant peers, pregnant persons are at higher risk for malaria infection. Malaria infection can occur at any time during pregnancy, with negative effects for the pregnant person and the fetus, depending on the trimester in which the infection is contracted. Pregnant patients who are younger, in their first or second pregnancy, and those coinfected with human immunodeficiency virus are at increased risk for malaria. Common infection prevention measures during pregnancy include the use of insecticide-treated bed nets and the use of intermittent preventive treatment with monthly doses of antimalarials, beginning in the second trimester in pregnant patients in endemic areas. In all trimesters, artemisinin-combination therapies are the first-line treatment for uncomplicated falciparum malaria, similar to treatment in nonpregnant adults. The World Health Organization recently revised its recommendations, now listing the specific medication artemether-lumefantrine as first-line treatment for uncomplicated malaria in the first trimester. While strong prevention and detection methods exist, use of these techniques remains below global targets. Ongoing work on approaches to treatment and prevention of malaria during pregnancy remains at the forefront of global maternal child health research.

Mosquito bed net use and associated factors among pregnant women in Rwanda: a nationwide survey

BACKGROUND

In malaria-endemic countries such as Rwanda, the appropriate use of mosquito bed nets is an effective intervention for malaria prevention. Despite being one of the demographics most impacted by malaria, there is a dearth of literature on the usage of mosquito bed nets by pregnant women in Rwanda. The study aimed to assess the prevalence and associated factors for mosquito bed net use among pregnant women in Rwanda.

METHODS

We used weighted data from the 2020 Rwanda Demographic and Health Survey of 870 pregnant women, and multistage stratified sampling was used to select participants. Multivariable logistic regression was conducted to determine the factors associated with mosquito bed net use, using SPSS (version 26).

RESULTS

Of the 870 pregnant women, 57.9% (95%CI: 54.6-61.1) used mosquito bed nets. However, 16.7% did not use bed nets among those owning bed nets. On one hand, older age (AOR = 1.59, 95%CI: 1.04-2.44), primary education (AOR = 1.18, 95%CI: 1.07-2.23), being married (AOR = 2.17, 95%CI: 1.43-3.20), being from Kigali region (AOR = 1.97, 95%CI: 1.19-3.91), partner's education (AOR = 1.22, 95%CI: 1.13-3.41), having recently visited a health facility (AOR = 2.07, 95%CI: 1.35-3.18), and being in the third pregnancy trimester (AOR = 2.14, 95%CI: 1.44-3.18) were positively associated with mosquito bed net use. On the other hand, low wealth index (AOR = 0.13, 95%CI: 0.07-0.24), and being from Eastern region (AOR = 0.42, 95% CI: 0.26-0.66) had a negative association.

CONCLUSIONS

About half of the pregnant women in Rwanda used mosquito bed nets and the usage was associated with various socio-demographics. There is a need for appropriate risk communication and continuous sensitisation to improve mosquito net use among pregnant women. Early antenatal care attendance and partner engagement in malaria prevention and mosquito net use, as well as consideration of household dynamics, are also crucial in improving not only mosquito net coverage but also utilization.

Malaria reduction drives childhood stunting decline in Uganda: a mixed-methods country case study

BACKGROUND

Uganda has achieved a considerable reduction in childhood stunting over the past 2 decades, although accelerated action will be needed to achieve 2030 targets.

OBJECTIVES

This study assessed the national, community, household, and individual-level drivers of stunting decline since 2000, along with direct and indirect nutrition policies and programs that have contributed to nutrition change in Uganda.

METHODS

This mixed-methods study used 4 different approaches to determine the drivers of stunting change over time: 1) a scoping literature review; 2) quantitative data analyses, including Oaxaca-Blinder decomposition and difference-in-difference multivariable hierarchical modeling; 3) national- and community-level qualitative data collection and analysis; and 4) analysis of key direct and indirect nutrition policies, programs, and initiatives.

RESULTS

Stunting prevalence declined by 14% points from 2000 to 2016, although geographical, wealth, urban/rural, and education-based inequalities persist. Child growth curves demonstrated substantial improvements in child height-for-age z-scores (HAZs) at birth, reflecting improved maternal nutrition and intrauterine growth. The decomposition analysis explained 82% of HAZ change, with increased coverage of insecticide-treated mosquito nets (ITNs; 35%), better maternal nutrition (19%), improved maternal education (14%), and improved maternal and newborn healthcare (11%) being the most critical factors. The qualitative analysis supported these findings, and also pointed to wealth, women's empowerment, cultural norms, water and sanitation, dietary intake/diversity, and reduced childhood illness as important. The 2011 Uganda Nutrition Action Plan was an essential multisectoral strategy that shifted nutrition out of health and mainstreamed it across related sectors.

CONCLUSIONS

Uganda's success in stunting reduction was multifactorial, but driven largely through indirect nutrition strategies delivered outside of health. To further improve stunting, it will be critical to prioritize malaria-control strategies, including ITN distribution campaigns and prevention/treatment approaches for mothers and children, and deliberately target the poor, least educated, and rural populations along with high-burden districts.

Immune Regulation, Maternal Infection, Vaccination, and Pregnancy Outcome

About 12.5% of all maternal deaths in the United States are due to infectious causes. This proportion, although stable during the past three decades, represents an increase in infectious causes of mortality, as the overall mortality rate in U.S. pregnant women had increased steadily during that same period. During healthy pregnancies, a delicate immunological balance-in which a mother's immune system tolerates the semi-allogeneic fetus yet maintains immune competency against infectious agents-is achieved and maintained. This immunological paradigm, however, results in increased susceptibility to infectious diseases during pregnancy, particularly in later stages and during the early postpartum period. The inflammatory process induced by these infectious insults, as well as some noninfectious insults, occurring during pregnancy can disrupt this carefully achieved balance and, in turn, lead to a state of rampant inflammation, immune activation, and dysregulation with deleterious health outcomes for the mother and fetus. Elucidating mechanisms contributing to the disruption of this immunologic homeostasis, and its disruption by infectious pathogens, might offer opportunities for interventions to reduce maternal and fetal morbidity and mortality.

Plasmodium malariae, current knowledge and future research opportunities on a neglected malaria parasite species

Plasmodium malariae is often reported as a benign malaria parasite. There are limited data on its biology and disease burden in sub-Saharan Africa (sSA) possibly due to the unavailability of specific and affordable tools for routine diagnosis and large epidemiology studies. In addition, P. malariae occurs at low parasite densities and in co-infections with other species, predominately P. falciparum. The paucity of data on P. malariae infections limits the capacity to accurately determine its contribution to malaria and the effect of control interventions against P. falciparum on its prevalence. Here, we summarise the current knowledge on P. malariae epidemiology in sSA - overall prevalence ranging from 0-32%, as detected by different diagnostic methods; seroprevalence ranging from 0-56% in three countries (Mozambique, Benin and Zimbabwe), and explore the future application of next-generation sequencing technologies as a tool for enriching P. malariae genomic epidemiology. This will provide insights into important adaptive mechanisms of this neglected non-falciparum species, including antimalarial drug resistance, local and regional parasite transmission patterns and genomic signatures of selection. Improved diagnosis and genomic surveillance of non-falciparum malaria parasites in Africa would be helpful in evaluating progress towards elimination of all human Plasmodium species.

Infant sex modifies associations between placental malaria and risk of malaria in infancy

Background

Placental malaria (PM) has been associated with a higher risk of malaria during infancy. However, it is unclear whether this association is causal, and is modified by infant sex, and whether intermittent preventive treatment in pregnancy (IPTp) can reduce infant malaria by preventing PM.

Methods

Data from a birth cohort of 656 infants born to HIV-uninfected mothers randomised to IPTp with dihydroartemisinin–piperaquine (DP) or Sulfadoxine–pyrimethamine (SP) was analysed. PM was categorized as no PM, active PM (presence of parasites), mild-moderate past PM (> 0–20% high powered fields [HPFs] with pigment), or severe past PM (> 20% HPFs with pigment). The association between PM and incidence of malaria in infants stratified by infant sex was examined. Causal mediation analysis was used to test whether IPTp can impact infant malaria incidence via preventing PM.

Results

There were 1088 malaria episodes diagnosed among infants during 596.6 person years of follow-up. Compared to infants born to mothers with no PM, the incidence of malaria was higher among infants born to mothers with active PM (adjusted incidence rate ratio [aIRR] 1.30, 95% CI 1.00–1.71, p = 0.05) and those born to mothers with severe past PM (aIRR 1.28, 95% CI 0.89–1.83, p = 0.18), but the differences were not statistically significant. However, when stratifying by infant sex, compared to no PM, severe past PM was associated a higher malaria incidence in male (aIRR 2.17, 95% CI 1.45–3.25, p < 0.001), but not female infants (aIRR 0.74, 95% CI 0.46–1.20, p = 0.22). There were no significant associations between active PM or mild-moderate past PM and malaria incidence in male or female infants. Male infants born to mothers given IPTp with DP had significantly less malaria in infancy than males born to mothers given SP, and 89.7% of this effect was mediated through prevention of PM.

Conclusion

PM may have more severe consequences for male infants, and interventions which reduce PM could mitigate these sex-specific adverse outcomes. More research is needed to better understand this sex-bias between PM and infant malaria risk.

Trial registration ClinicalTrials.gov, NCT02793622. Registered 8 June 2016, https://clinicaltrials.gov/ct2/show/NCT02793622

Malaria preventive practices and delivery outcomes: A cross-sectional study of parturient women in a tertiary hospital in Eastern Uganda

BACKGROUND

Uganda ranks third in the number of deaths attributable to malaria and has some of the highest recorded malaria transmission rates in the general population. Malaria in Pregnancy is associated with detrimental effects for the mother and unborn baby and these effects seem to have long term effects and consequences on the life of the baby. Despite the preventive measures put in place by the World Health Organization in antenatal care, the burden of malaria in pregnancy is still high. We determined the use of malaria preventive strategies during pregnancy and the presence of plasmodium infection, anemia, and low birth weight babies at delivery among parturient women at Mbale regional referral hospital in eastern Uganda.

METHODS

A cross-sectional study was conducted among 210 women delivering at MRRH between July 2017 and January 2018. Information on demographics, antenatal care, and prevention practices was collected using an interviewer-administered questionnaire. Maternal venous blood and cord blood samples were screened for Plasmodium infection by both microscopy of Giemsa-stained blood films and Plasmodium falciparum rapid diagnostic test (pf. HPR2 mRDT). Polymerase Chain Reaction (PCR) was done on cord blood. The presence of anemia was determined by the use of an automated hemoglobin analyzer. Data were analyzed using descriptive and analytical statistics.

RESULTS

Of the 210 women, 3 (1.4%) and 19(9.1%) tested positive for malaria by using Giemsa stained blood smear microscopy and malaria rapid diagnosticMRDT tests respectively. PCR detected 4(%) of Plasmodium in cord blood. Twenty-nine percent of the women had anaemia and 11 (5.2%) had low birth weight babies. Only 23.3% of the women received at least three doses of IPTp-SP and 57.9% reported sleeping under an Insecticide Treated Net the night before the survey. The women who reported sleeping under a mosquito net the previous night (OR 0.67, 95% CI: 0.24-1.86) and those who reported taking fansidar as a directly observed therapy (OR 0.31, 95% CI: 0.04-2.39) appeared to have few chances of getting plasmodium infection though the findings were not statistically significant.

CONCLUSION

The effective use of malaria preventive strategies (IPT-SP and Insecticide Treated Nets) was generally low. Most of the women took less than three doses of SP and there was no strict adherence to the recommended directly observed therapy. The prevalence of Plasmodium infection during pregnancy was low though maternal anaemia and low birth weight were relatively high.

Impact of Malaria in Pregnancy on Risk of Malaria in Young Children: Systematic Review and Meta-Analyses

BACKGROUND

Our objective was to quantify the risk of acquiring malaria among progeny of women with malaria during pregnancy.

METHODS

We searched MEDLINE, EMBASE, CINAHL, and the Cochrane Library for eligible prospective studies. The primary predictor was malaria during pregnancy defined as placental malaria, parasitemia, clinical malaria, or pregnancy-associated malaria. Primary outcomes were parasitemia or clinically defined malaria of young children. We performed meta-analyses to pool adjusted risk estimates using a random-effects model.

RESULTS

Nineteen of 2053 eligible studies met inclusion criteria for the systemic review. Eleven of these studies were quantitative and were included in the meta-analyses. The pooled adjusted odds ratio (aOR) or adjusted hazard ratio (aHR) of malaria during pregnancy for detection of parasitemia in young children were 1.94 (95% confidence interval [CI], 0.93-4.07; P = .08) and 1.46 (95% CI, 1.07-2.00; P < .001), respectively. The pooled aOR or aHR for clinically defined malaria in young children were 2.82 (95% CI, 1.82-4.38; P < .001) and 1.31 (95% CI, 0.96-1.79; P = .09), respectively.

CONCLUSIONS

Our results confirmed that malaria during pregnancy significantly increased the overall risk of malaria in young children via indeterminate mechanisms and emphasize the urgent need to implement safe and highly effective strategies to prevent malaria during pregnancy.

Impact of Microscopic and Submicroscopic Parasitemia During Pregnancy on Placental Malaria in a High-Transmission Setting in Uganda

BACKGROUND

Placental malaria is a major cause of adverse birth outcomes. However, data are limited on the relationships between longitudinal measures of parasitemia during pregnancy and placental malaria.

METHODS

Data came from 637 women enrolled in a randomized controlled trial of intermittent preventive treatment of malaria in pregnancy (IPTp) from Uganda. Plasmodium falciparum parasitemia was assessed using microscopy and ultrasensitive quantitative PCR at intervals of 28 days from 12 to 20 weeks gestation through delivery. Multivariate analysis was used to measure associations between characteristics of parasitemia during pregnancy and the risk of placental malaria based on histopathology.

RESULTS

Overall risk of placental malaria was 44.6%. None of the 34 women without parasitemia detected during pregnancy had evidence of placental malaria. Increasing proportion of interval assessments with parasitemia and higher parasite densities were independently associated with an increased risk of placental malaria. Higher gravidity and more effective IPTp were associated with a decreased risk of placental malaria. Women with parasitemia only detected before the third trimester still had an increased risk of placental malaria.

CONCLUSIONS

The frequency, density, and timing of parasitemia are all important risk factors for placental malaria. Interventions should target the prevention of all levels of parasitemia throughout pregnancy.

Ex vivo efficacy of selective chalcone derivatives on reference strains and field isolates of Plasmodium falciparum

The extension of Plasmodium falciparum resistance to existing antimalarial drugs is worrying. Faced with this problem, the search for new and effective molecules is necessary. In this context, six chalcone derivatives (B1, B11, B14, B17, SCA02 and SCA03) were tested on field isolates and then reference strains to evaluate their antiplasmodial activity by using the Rieckmann semi-microtest, recommended by WHO, for in vitro and ex vivo activity tests. Compounds B14 and B17 exhibited promising antiplasmodial activities (IC_50s: 14.41-16.40 μM) regardless of the type of isolate. Compounds B1, B11, SCA02 and SCA03 showed a moderate inhibition of field isolates (IC_50S: 25.63-48.29 μM) and very good activity against reference strains (IC50s: 3.82-10.03 μM). Therefore, more structural modulations should improve their efficiency and make these molecules very good candidates for future effective antimalarial drugs.

Increased Risk of Malaria During the First Year of Life in Small-for-Gestational-Age Infants: A Longitudinal Study in Benin

BACKGROUND

According to the Developmental Origins of Health and Diseases paradigm, the fetal period is highly vulnerable and may have profound effects on later health. Few studies assessed the effect of small-for-gestational age (SGA), a proxy for fetal growth impairment, on risk of malaria during infancy in Africa.

METHODS

We used data from a cohort of 398 mother-child pairs, followed from early pregnancy to age 1 year in Benin. Malaria was actively and passively screened using thick blood smear. We assessed the effect of SGA on risk of malaria infection and clinical malaria from birth to 12 months, after stratifying on the infant's age using a logistic mixed regression model.

RESULTS

After adjustment for potential confounding factors and infant's exposure to mosquitoes, SGA was associated with a 2-times higher risk of malaria infection (adjusted odds ratio [aOR] = 2.16; 95% confidence interval [CI], 1.04-4.51; P = .039) and clinical malaria (aOR = 2.33; 95% CI, 1.09-4.98; P = .030) after age 6 months.

CONCLUSION

Results suggest higher risk of malaria during the second semester of life in SGA infants, and argue for better follow-up of these infants after birth, as currently for preterm babies.

Key Infections in the Placenta

Congenital infections are an important cause of morbidity and mortality worldwide, especially in low-income settings. This review discusses the main pathways of infections and associated adverse maternal and fetal outcomes, considering the TORCH pathogens, including Zika virus; the acronym stands for Toxoplasma gondii infection, other (Listeria monocytogenes, Treponema pallidum, and parvovirus B19, among others, including Zika virus), rubella virus, cytomegalovirus, and herpes simplex viruses type 1 and type 2.

Zika virus infection in pregnancy and infant growth, body composition in the first three months of life: a cohort study

The implications of Zika Virus exposure in pregnancy for early infant growth remains poorly described. The main goal of this study is to compare the growth, body composition, and feeding modality of infants in the first three months of life by prenatal Zika Virus exposure status. We selected an analytical cohort of 115 infants born without microcephaly, comprising 56 infants with qRT-PCR confirmed exposure to ZIKV during gestation and 59 infants born to women with presumptively no evidence of ZIKV in pregnancy. Infants were evaluated at birth, 1 and 3 months of age in terms of anthropometrics, body composition All the results were adjusted by maternal age, maternal BMI and gestational age. We observe no differences between anthropometric measurements at birth. Mothers in exposed group showed higher BMI. At 1 month and 3 months of age there were differences in mid arm circumference, arm muscle circumference and fat free mass. Weight and length was less in the ZIKV exposed in pregnancy infants and statistically different at 3 month of age. The findings of this investigation provide new evidence that ZIKV exposure in pregnancy may be associated with differences in body composition.

Early malaria infection, dysregulation of angiogenesis, metabolism and inflammation across pregnancy, and risk of preterm birth in Malawi: A cohort study

BACKGROUND

Malaria in pregnancy is associated with adverse birth outcomes. However, the underlying mechanisms remain poorly understood. Tight regulation of angiogenic, metabolic, and inflammatory pathways are essential for healthy pregnancies. We hypothesized that malaria disrupts these pathways leading to preterm birth (PTB).

METHODS AND FINDINGS

We conducted a secondary analysis of a randomized trial of malaria prevention in pregnancy conducted in Malawi from July 21, 2011, to March 18, 2013. We longitudinally assessed circulating mediators of angiogenic, metabolic, and inflammatory pathways during pregnancy in a cohort of HIV-negative women (n = 1,628), with a median age of 21 years [18, 25], and 562 (35%) were primigravid. Pregnancies were ultrasound dated, and samples were analyzed at 13 to 23 weeks (Visit 1), 28 to 33 weeks (Visit 2), and/or 34 to 36 weeks (Visit 3). Malaria prevalence was high; 70% (n = 1,138) had PCR-positive Plasmodium falciparum infection at least once over the course of pregnancy and/or positive placental histology. The risk of delivering preterm in the entire cohort was 20% (n = 304/1506). Women with malaria before 24 weeks gestation had a higher risk of PTB (24% versus 18%, p = 0.005; adjusted relative risk [aRR] 1.30, 95% confidence interval [CI] 1.04-1.63, p = 0.021); and those who were malaria positive only before week 24 had an even greater risk of PTB (28% versus 17%, p = 0.02; with an aRR of 1.67, 95% CI 1.20-2.30, p = 0.002). Using linear mixed-effects modeling, malaria before 24 weeks gestation was associated with altered kinetics of inflammatory (C-Reactive Protein [CRP], Chitinase 3-like protein-1 [CHI3L1], Interleukin 18 Binding Protein [IL-18BP], soluble Tumor Necrosis Factor receptor II [sTNFRII], soluble Intercellular Adhesion Molecule-1 [sICAM-1]), angiogenic (soluble Endoglin [sEng]), and metabolic mediators (Leptin, Angiopoietin-like 3 [Angptl3]) over the course of pregnancy (χ2 > 13.0, p ≤ 0.001 for each). Limitations include being underpowered to assess the impact on nonviable births, being unable to assess women who had not received any antimalarials, and, because of the exposure to antimalarials in the second trimester, there were limited numbers of malaria infections late in pregnancy.

CONCLUSIONS

Current interventions for the prevention of malaria in pregnancy are initiated at the first antenatal visit, usually in the second trimester. In this study, we found that many women are already malaria-infected by their first visit. Malaria infection before 24 weeks gestation was associated with dysregulation of essential regulators of angiogenesis, metabolism, and inflammation and an increased risk of PTB. Preventing malaria earlier in pregnancy may reduce placental dysfunction and thereby improve birth outcomes in malaria-endemic settings.

The immune response to malaria in utero

Malaria causes tremendous early childhood morbidity and mortality, providing an urgent impetus for the development of a vaccine that is effective in neonates. However, the infant immune response to malaria may be influenced by events that occur well before birth. Placental malaria infection complicates one quarter of all pregnancies in Africa and frequently results in exposure of the fetus to malaria antigens in utero, while the immune system is still developing. Some data suggest that in utero exposure to malaria may induce immunologic tolerance that interferes with the development of protective immunity during childhood. More recently, however, a growing body of evidence suggests that fetal malaria exposure can prime highly functional malaria-specific T- and B-cells, which may contribute to postnatal protection from malaria. In utero exposure to malaria also impacts the activation and maturation of fetal antigen presenting cells and innate lymphocytes, which could have implications for global immunity in the infant. Here, we review recent advances in our understanding of how various components of the fetal immune system are altered by in utero exposure to malaria, discuss factors that may tilt the critical balance between tolerance and adaptive immunity, and consider the implications of these findings for malaria prevention strategies.

Impact of Plasmodium falciparum malaria and intermittent preventive treatment of malaria in pregnancy on the risk of malaria in infants: a systematic review

Background

Studies of the association between malaria in pregnancy (MiP) and malaria during infancy have provided mixed results. A systematic review was conducted to evaluate available evidence on the impact of Plasmodium falciparum malaria infection during pregnancy, and intermittent preventive treatment of malaria during pregnancy (IPTp), on the risk of clinical malaria or parasitaemia during infancy.

Methods

MEDLINE, EMBASE, Global Health, and Malaria in Pregnancy Library databases were searched from inception to 22 May 2018 for articles published in English that reported on associations between MiP and malaria risk in infancy. Search terms included malaria, Plasmodium falciparum, pregnancy, placenta, maternal, prenatal, foetal, newborn, infant, child or offspring or preschool. Randomized controlled trials and prospective cohort studies, which followed infants for at least 6 months, were included if any of the following outcomes were reported: incidence of clinical malaria, prevalence of parasitaemia, and time to first episode of parasitaemia or clinical malaria. Substantial heterogeneity between studies precluded meta-analysis. Thus, a narrative synthesis of included studies was conducted.

Results

The search yielded 14 published studies, 10 prospective cohort studies and four randomized trials; all were conducted in sub-Saharan Africa. Infants born to mothers with parasitaemia during pregnancy were at higher risk of malaria in three of four studies that assessed this association. Placental malaria detected by microscopy or histology was associated with a higher risk of malaria during infancy in nine of 12 studies, but only one study adjusted for malaria transmission intensity. No statistically significant associations between the use of IPTp or different IPTp regimens and the risk of malaria during infancy were identified.

Conclusion

Evidence of an association between MiP and IPTp and risk of malaria in infancy is limited and of variable quality. Most studies did not adequately adjust for malaria transmission intensity shared by mothers and their infants. Further research is needed to confirm or exclude an association between MiP and malaria in infancy. Randomized trials evaluating highly effective interventions aimed at preventing MiP, such as IPTp with dihydroartemisinin–piperaquine, may help to establish a causal association between MiP and malaria in infancy.

An overview of malaria in pregnancy

One hundred twenty-five million pregnant women are at risk for contracting malaria, a preventable cause of maternal and infant morbidity and death. Malaria parasites contribute to adverse pregnancy and birth outcomes due to their preferential accumulation in placental intervillous spaces. Pregnant women are particularly vulnerable to malaria infections, and malaria infections during pregnancy put their fetuses at risk. Malaria in pregnancy is associated with anemia, stillbirth, low birth weight and maternal and fetal death. We review the challenges to diagnosing malaria in pregnancy, as well as strategies to prevent and treat malaria in pregnancy. Finally, we discuss the current gaps in knowledge and potential areas for continued research.

Genesis of placental sequestration in malaria and possible targets for drugs for placental malaria

Malaria during pregnancy results in intrauterine growth restriction, fetal anemia, and infant mortality. Women are more susceptible to malaria during pregnancy due to malaria‐induced inflammation and the sequestration of infected red blood cells in the placenta, which bind to the chondroitin sulfate portion of syndecan‐1 on the syncytiotrophoblast and in the intervillous space. Syndecan‐1 is a dimeric proteoglycan with an extracellular ectodomain that is cleaved from the transmembrane domain (referred to as “shedding”) by matrix metalloproteinases (MMPs), likely the secreted MMP‐9. The ectodomain includes four binding sites for chondroitin sulfate, which are proximal to the transmembrane domain, and six distal binding sites primarily for heparan sulfate. This “shedding” of syndecan‐1 is inhibited by the presence of the heparan sulfate chains, which can be removed by heparanase. The intervillous space contains fibrin strands and syndecan‐1 ectodomains free of heparan sulfate. The following is proposed as the sequence of events that leads to and is primarily responsible for sequestration in the intervillous space of the placenta. Inflammation associated with malaria triggers increased heparanase activity that degrades the heparan sulfate on the membrane‐bound syndecan‐1. Inflammation also upregulates MMP‐9 and the removal of heparan sulfate gives MMP‐9 access to cleave syndecan‐1, thereby releasing dimeric syndecan‐1 ectodomains with at least four chondroitin sulfate chains attached. These multivalent ectodomains bind infected RBCs together leading to their aggregation and entrapment in intervillous fibrin. This mechanism suggests possible new targets for anti‐placental malaria drugs such as the inhibition of MMP‐9. Doxycycline is an antimalarial drug which inhibits MMP‐9.

Malaria in pregnancy shapes the development of foetal and infant immunity

Malaria, particularly Plasmodium falciparum, continues to disproportionately affect pregnant women. In addition to the profoundly deleterious impact of maternal malaria on the health of the mother and foetus, malaria infection in pregnancy has been shown to affect the development of the foetal and infant immune system and may alter the risk of malaria and nonmalarial outcomes during infancy. This review summarizes our current understanding of how malaria infection in pregnancy shapes the protective components of the maternal immune system transferred to the foetus and how foetal exposure to parasite antigens impacts the development of foetal and infant immunity. It also reviews existing evidence linking malaria infection in pregnancy to malaria and nonmalarial outcomes in infancy and how preventing malaria in pregnancy may alter these outcomes. A better understanding of the consequences of malaria infection in pregnancy on the development of foetal and infant immunity will inform control strategies, including intermittent preventive treatment in pregnancy and vaccine development.

Geostatistical modelling of the association between malaria and child growth in Africa

Background

Undernutrition among children under 5 years of age continues to be a public health challenge in many low- and middle-income countries and can lead to growth stunting. Infectious diseases may also affect child growth, however their actual impact on the latter can be difficult to quantify. In this paper, we analyse data from 20 Demographic and Health Surveys (DHS) conducted in 13 African countries to investigate the relationship between malaria and stunting. Our objective is to make inference on the association between malaria incidence during the first year of life and height-for-age Z-scores (HAZs).

Methods

We develop a geostatistical model for HAZs as a function of both measured and unmeasured child-specific and spatial risk factors. We visualize stunting risk in each of the 20 analysed surveys by mapping the predictive probability that HAZ is below − 2. Finally, we carry out a meta-analysis by modelling the estimated effects of malaria incidence on HAZ from each DHS as a linear regression on national development indicators from the World Bank.

Results

A non-spatial univariate linear regression of HAZ on malaria incidence showed a negative association in 18 out of 20 surveys. However, after adjusting for spatial risk factors and controlling for confounding effects, we found a weaker association between HAZ and malaria, with a mix of positive and negative estimates, of which 3 out of 20 are significantly different from zero at the conventional 5% level. The meta-analysis showed that this variation in the estimated effect of malaria incidence on HAZ is significantly associated with the amount of arable land.

Conclusion

Confounding effects on the association between malaria and stunting vary both by country and over time. Geostatistical analysis provides a useful framework that allows to account for unmeasured spatial confounders. Establishing whether the association between malaria and stunting is causal would require longitudinal follow-up data on individual children.

Electronic supplementary material

The online version of this article (10.1186/s12942-018-0127-y) contains supplementary material, which is available to authorized users.

Burden, pathology, and costs of malaria in pregnancy: new developments for an old problem

Over the past 10 years, knowledge of the burden, economic costs, and consequences of malaria in pregnancy has improved, and the prevalence of malaria caused by Plasmodium falciparum has declined substantially in some geographical areas. In particular, studies outside of Africa have increased the evidence base of Plasmodium vivax in pregnancy. Rapid diagnostic tests have been poor at detecting malaria in pregnant women, while PCR has shown a high prevalence of low density infection, the clinical importance of which is unknown. Erythrocytes infected with P falciparum that express the surface protein VAR2CSA accumulate in the placenta, and VAR2CSA is an important target of protective immunity. Clinical trials for a VAR2CSA vaccine are ongoing, but sequence variation needs to be carefully studied. Health system and household costs still limit access to prevention and treatment services. Within the context of malaria elimination, pregnant women could be used to monitor malaria transmission. This Series paper summarises recent progress and highlights unresolved issues related to the burden of malaria in pregnancy.

Increased Susceptibility to Plasmodium falciparum in Infants is associated with Low, not High, Placental Malaria Parasitemia

Risk of malaria in infants can be influenced by prenatal factors. In this study, the potential for placental parasitemia at delivery in predicting susceptibility of infants to Plasmodium falciparum (Pf) infections was evaluated. Seventy-two newborns of mothers who were placental malaria negative (PM-) and of mothers who were PM+ with below (PM+ Lo) and above (PM + Hi) median placental parasitemia, were actively monitored during their first year of life. Median time to first PCR-detected Pf infection was shorter in PM + Lo infants (2.8 months) than in both PM- infants (4.0 months, p = 0.002) and PM + Hi infants (4.1 months, p = 0.01). Total number of new infections was also highest in the PM + Lo group. Only 24% of infants experienced clinical malaria episodes but these episodes occurred earlier in PM + Lo infants than in PM + Hi infants (p = 0.05). The adjusted hazard ratio (95% CI) of having Pf infection was 3.9 (1.8-8.4) and 1.5 (0.7-3.4) for infants in the PM + Lo and PM + Hi groups, respectively. Collectively, low placental parasitemia was associated with increased susceptibility to malaria during infancy. Therefore, malaria in pregnancy preventive regimens, such as sulfadoxine-pyremethamine, that reduce but do not eliminate placental Pf in areas of drug resistance may increase the risk of malaria in infants.

Methodology of assessment and reporting of safety in anti-malarial treatment efficacy studies of uncomplicated falciparum malaria in pregnancy: a systematic literature review

Background

Considering the uncertainty of safety of anti-malarial drugs in pregnancy, efficacy studies are one of the few sources of clinical safety data. Complete safety evaluation is not usually incorporated in efficacy studies due to financial and human resource constraints. This review reports the methods used for the assessment of safety of artemisinin-based and quinine-based treatments in efficacy studies in pregnancy.

Methods

Methodology of assessment and reporting of safety in efficacy studies of artemisinin-based and quinine-based treatment in pregnancy was reviewed using seven databases and two clinical trial registries. The protocol was registered to PROSPERO (CRD42017054808).

Results

Of 48 eligible efficacy studies the method of estimation of gestational age was reported in only 32 studies (67%, 32/48) and ultrasound was used in 18 studies (38%, 18/48). Seventeen studies (35%, 17/48) reported parity, 9 (19%, 9/48) reported gravidity and 13 (27%, 13/48) reported both. Thirty-eight studies (79%, 38/48) followed participants through to pregnancy outcome. Fetal loss was assessed in 34 studies (89%, 34/38), but the definition of miscarriage and stillbirth were defined only in 11 (32%, 11/34) and 7 (21%, 7/34) studies, respectively. Preterm birth was assessed in 26 studies (68%, 26/38) but was defined in 16 studies (62%, 16/26). Newborn weight was assessed in 30 studies (79%, 30/38) and length in 10 studies (26%, 10/38). Assessment of birth weight took gestational age into account in four studies (13%, 4/30). Congenital abnormalities were reported in 32 studies (84%, 32/38). Other common risk factors for adverse pregnancy outcomes were not well-reported.

Conclusion

Incomplete reporting and varied methodological assessment of pregnancy outcomes in anti-malarial drug efficacy studies limits comparison across studies. A standard list of minimal necessary parameters to assess and report the safety component of efficacy studies of anti-malarials in pregnancy is proposed.

Electronic supplementary material

The online version of this article (10.1186/s12936-017-2136-x) contains supplementary material, which is available to authorized users.

The US President's Malaria Initiative and under-5 child mortality in sub-Saharan Africa: A difference-in-differences analysis

BACKGROUND

Despite substantial financial contributions by the United States President's Malaria Initiative (PMI) since 2006, no studies have carefully assessed how this program may have affected important population-level health outcomes. We utilized multiple publicly available data sources to evaluate the association between introduction of PMI and child mortality rates in sub-Saharan Africa (SSA).

METHODS AND FINDINGS

We used difference-in-differences analyses to compare trends in the primary outcome of under-5 mortality rates and secondary outcomes reflecting population coverage of malaria interventions in 19 PMI-recipient and 13 non-recipient countries between 1995 and 2014. The analyses controlled for presence and intensity of other large funding sources, individual and household characteristics, and country and year fixed effects. PMI program implementation was associated with a significant reduction in the annual risk of under-5 child mortality (adjusted risk ratio [RR] 0.84, 95% CI 0.74-0.96). Each dollar of per-capita PMI expenditures in a country, a measure of PMI intensity, was also associated with a reduction in child mortality (RR 0.86, 95% CI 0.78-0.93). We estimated that the under-5 mortality rate in PMI countries was reduced from 28.9 to 24.3 per 1,000 person-years. Population coverage of insecticide-treated nets increased by 8.34 percentage points (95% CI 0.86-15.83) and coverage of indoor residual spraying increased by 6.63 percentage points (95% CI 0.79-12.47) after PMI implementation. Per-capita PMI spending was also associated with a modest increase in artemisinin-based combination therapy coverage (3.56 percentage point increase, 95% CI -0.07-7.19), though this association was only marginally significant (p = 0.054). Our results were robust to several sensitivity analyses. Because our study design leaves open the possibility of unmeasured confounding, we cannot definitively interpret these results as causal.

CONCLUSIONS

PMI may have significantly contributed to reducing the burden of malaria in SSA and reducing the number of child deaths in the region. Introduction of PMI was associated with increased coverage of malaria prevention technologies, which are important mechanisms through which child mortality can be reduced. To our knowledge, this study is the first to assess the association between PMI and all-cause child mortality in SSA with the use of appropriate comparison groups and adjustments for regional trends in child mortality.

Prenatal exposure to Plasmodium falciparum increases frequency and shortens time from birth to first clinical malaria episodes during the first two years of life: prospective birth cohort study

Background

Prenatal exposure to Plasmodium falciparum affects development of protective immunity and susceptibility to subsequent natural challenges with similar parasite antigens. However, the nature of these effects has not been fully elucidated. The aim of this study was to determine the effect of prenatal exposure to P. falciparum on susceptibility to natural malaria infection, with a focus on median time from birth to first clinical malaria episode and frequency of clinical malaria episodes in the first 2 years of life.

Methods

A prospective birth cohort study was conducted in Rufiji district in Tanzania, between January 2013 and December 2015. Infants born to mothers with P. falciparum in the placenta at time of delivery were defined as exposed, and infants born to mothers without P. falciparum parasites in placenta were defined as unexposed. Placental infection was established by histological techniques. Out of 206 infants recruited, 41 were in utero exposed to P. falciparum and 165 infants were unexposed. All infants were monitored for onset of clinical malaria episodes in the first 2 years of life. The outcome measure was time from birth to first clinical malaria episode, defined by fever (≥37 °C) and microscopically determined parasitaemia. Median time to first clinical malaria episode between exposed and unexposed infants was assessed using Kaplan–Meier survival analysis and comparison was done by log rank. Association of clinical malaria episodes with prenatal exposure to P. falciparum was assessed by multivariate binary logistic regression. Comparative analysis of mean number of clinical malaria episodes between exposed and unexposed infants was done using independent sample t test.

Results

The effect of prenatal exposure to P. falciparum infection on clinical malaria episodes was statistically significant (Odds Ratio of 4.79, 95 % CI 2.21–10.38, p < 0.01) when compared to other confounding factors. Median time from birth to first clinical malaria episode for exposed and unexposed infants was 32 weeks (95 % CI 30.88–33.12) and 37 weeks (95 % CI 35.25–38.75), respectively, and the difference was statistically significant (p = 0.003). The mean number of clinical malaria episodes in exposed and unexposed infants was 0.51 and 0.30 episodes/infant, respectively, and the difference was statistically significant (p = 0.038).

Conclusions

Prenatal exposure to P. falciparum shortens time from birth to first clinical malaria episode and increases frequency of clinical malaria episodes in the first 2 years of life.