Parasite dynamics in the peripheral blood and the placenta during pregnancy-associated malaria infection

Distribution of ABO and rhesus blood grouping with HIV infection among blood donors in Ekiti State Nigeria

Erythrocyte antigens, particularly those which give rise to different blood group systems, are potentially known to perform as receptor sites for different types of disease-causing agents. It is for this reason that this study was carried out to determine the distribution of different blood groups and how susceptible they are to human immunodeficiency virus (HIV) infection. For this study, data were retrieved from different blood bank registers at 4 major blood banks in Ekiti State (National Blood Transfusion Services, Ado, State Specialist Hospital, Ikole, State Specialist Hospital, Ijero, State Specialist Hospital, Ikere. All in Ekiti State). Demographic data such as age and gender were collected on 2388 individuals who were recruited at the above stated facilities over a 2-year period. Their blood groups (Rhesus and ABO) and HIV status were equally recorded. Results of the ABO blood group analysis of the subjects showed that Blood Group O had the highest population (78.2%) while blood Group AB had the lowest (0.9%). The percentages of Rhesus positive and negative persons observed in this population were 94.7% and 5.3%, respectively. The total sero-prevalence of HIV infection was 0.81%. However, there was no significant difference in the prevalence of HIV among the different ABO and Rhesus blood types. This study revealed no association between ABO and Rhesus blood groups and HIV infection.

Insecticide-treated net utilization and associated factors among pregnant women in East Africa: evidence from the recent national demographic and health surveys, 2011-2022

BACKGROUND

The pregnant woman, the fetus, and the newborn child are all at risk from malaria infection in sub-Saharan Africa. Employing insecticide-treated mosquito nets (ITNs) is one of the most efficient methods for avoiding malaria among expectant mothers. However, there is no literature that describes ITN use among pregnant women in East Africa or the contributing factors. Therefore, this study sought to identify the factors affecting pregnant women's ITN utilization in East Africa.

METHODS

The most recent DHS (Demographic and Health Survey) data for the 11 East African countries from 2011 to 2022 was used. 13,729 pregnant women were examined. To identify factors associated with ITN use, a binary and multiple logistic regression model was built. Variables having a p-value of less than or equal to 0.2 in the binary logistic regression analysis were taken into consideration for the multivariable analysis. In the multiple logistic regression analysis, the adjusted Odds Ratio (aOR) with the 95% Confidence Interval (CI) was provided to proclaim the statistical significance and degree of correlation.

RESULTS

The survey found that just 47.05% (95% CI 46.21, 47.88) of pregnant mothers reported using ITNs. The highest and lowest values were seen in Uganda (64.13%) and Zimbabwe (6.08%). Women age 25-34y (aOR = 1.19; 95% CI 1.11, 1.29), 35-49y (aOR = 1.26; 95% CI 1.13, 1.41) as compared to 15-24 years, poorer (aOR = 1.15; 95% CI 1.04-1.27), middle (aOR = 1.21; 95% CI 1.09, 1.35), and rich (aOR = 1.18; 95% CI 1.06, 1.31) wealth indexes as compared to poorest, having > 5 family size (AOR = 0.84; 95% CI 0.78, 0.91) primary (aOR = 1.49; 95% CI 1.36, 1.65), and secondary/higher education (aOR = 1.52; 95% CI 1.35, 1.70) as compared to not educated, and married women (aOR = 1.64; 95% CI 1.44, 1.86) have shown a statistically significant association with ITN utilization among pregnant women.

CONCLUSION

With a variety of risk variables, including age, wealth, family size, and education, pregnant women in East Africa rarely use ITNs. There is a need to create and strengthen malaria prevention programmes, especially among pregnant women who do not use ITNs, based on the variables mentioned.

Insecticide-treated bed net utilization and associated factors among pregnant women in Ethiopia: a systematic review and meta-analysis

BACKGROUND

Malaria infection during pregnancy endangers the pregnant woman, fetus, and newborn child. Thus, the use of an insecticide-treated net (ITN) is one of the most frequently advised methods for preventing malaria during pregnancy. Contrary findings have been reported in various studies on ITN utilization among pregnant women in Ethiopia. Therefore, this study was aimed to estimate the pooled prevalence of ITN utilization and its associated factors among pregnant women in Ethiopia.

METHODS

Published articles from PubMed, Google Scholar, Science Direct, AJOL and Cochrane library were systematically searched. All cross-sectional studies on ITN utilization among pregnant women were included in this meta-analysis. To estimate the pooled prevalence and odds ratio, a random-effect model was used; and a subgroup analysis was performed to identify the possible source of heterogeneity. Begg's and Egger's tests were used to identify possible publication bias.

RESULTS

Ten cross-sectional studies with 7,161 participants were included. The pooled prevalence of ITN utilization among all pregnant women who had access to ITN in Ethiopia was 59.42% (95% CI 51.14, 67.69). Statistically significant heterogeneity was observed (I2 = 97.7%; p < 0.0001). Higher educational status (OR = 3.47, 95% CI   2.32, 5.2), pregnant women who had antenatal care visits (OR = 2.37, 95% CI 1.97, 2.65) and having good knowledge of malaria prevention practices (OR = 10.63, 95% CI   5.31, 21.29) were associated with ITN utilization among pregnant women.

CONCLUSION

The utilization of ITNs among pregnant women was much lower than the national target. Higher education status, attending ANC and a good level of knowledge were found to be independent predictors of ITN utilization. Improving women's understanding of ITNs will enhance their use, and the government and health sectors should encourage pregnant mothers to enroll in antenatal care.

Considerations for the Use of Long-Acting and Extended-Release Agents During Pregnancy and Lactation

Long-acting agents hold significant promise for treating and preventing common illnesses, including infections. Pharmacokinetic and safety data during pregnancy and lactation are often unavailable for new drugs; these data are vital to facilitate optimal drug use by pregnant and lactating women and women who may conceive. In this commentary, we summarize the circumstances in which pregnant and lactating women are likely to use and benefit from long-acting agents. We focus on long-acting formulations of small molecules (rather than biologics such as monoclonal antibodies) and on several infections of global importance (human immunodeficiency virus, tuberculosis, malaria, and hepatitis C). We discuss pregnancy pharmacokinetic/pharmacodynamic and potential safety and efficacy considerations pertaining to the use of long-acting agents in pregnancy and lactation. Finally, we summarize existing preclinical and pregnancy pharmacokinetic data that are available (or expected in the near future) for several agents that are under development or approved, and how key research gaps may be addressed.

Safety of Treating Malaria with Artemisinin-Based Combination Therapy in the First Trimester of Pregnancy

There have been recent calls for the use of artemisinin-based combination therapies (ACTs) for uncomplicated malaria in the first trimester of pregnancy. Nevertheless, the 2021 WHO Guidelines for Malaria reaffirmed their position that there is not adequate clinical safety data on artemisinins to support that usage. The WHO's position is consistent with several issues with the existing clinical data. First, first trimester safety results from multiple ACTs were lumped in a meta-analysis which does not demonstrate that each of the included ACTs is equally safe. Second, safety results from all periods of the first trimester were lumped in the meta-analysis which does not demonstrate the same level of safety for all subperiods, particularly gestational Weeks 6 to 8 which is likely to be the most sensitive period. Third, even if there is evidence of a lack of an effect on miscarriage for a particular ACT, it does not follow then there are no developmental effects for any ACT. In monkeys, artesunate caused marked embryonal anemia leading to embryo death but the long-term consequences of lower levels of embryonal anemia are not known. Fourth, there have been advances in the sensitivity and usage of rapid diagnostic tests that will lead to diagnoses of malaria earlier in gestation which is less well studied and more likely sensitive to artemisinins. Any clinical studies of the safety of ACTs in the first trimester need to evaluate the results of treatment with individual ACTs during different 1- to 2-week periods of the first trimester.

Assessing field performance of ultrasensitive rapid diagnostic tests for malaria: a systematic review and meta-analysis

Background

To overcome the limitations of conventional malaria rapid diagnostic tests (cRDTs) in diagnosing malaria in patients with low parasitaemia, ultrasensitive malaria rapid diagnostic tests (uRDTs) have recently been developed, with promising results under laboratory conditions. The current study is the first meta-analysis comparing the overall sensitivity, and specificity of newly developed ultrasensitive Plasmodium falciparum malaria RDT (Alere™ Ultra-sensitive Malaria Ag P. falciparum RDT) with the cRDT conducted in the same field conditions.

Methods

PubMed, EMBASE, Cochrane infectious diseases group specialized register, and African Journals Online (AJOL) were searched up to 20^th April 2021. Studies with enough data to compute sensitivity and specificity of uRDT and cRDT were retrieved. A random-effect model for meta-analysis was used to obtain the pooled sensitivity and specificity.

Results

Overall, 15 data sets from 14 studies were included in the meta-analysis. The overall sensitivity of the Alere™ ultra-sensitive Malaria Ag P. falciparum RDT regardless of the reference test and the clinical presentation of participants, was 55.5% (95% confidence interval [CI]: 45.5; 65.0), while the sensitivity regardless of the reference test and the clinical presentation of participants, was 42.9% (95% CI: 31.5; 55.2) for the cRDT performed in the same field conditions. When PCR was used as reference test, the sensitivity of uRDT was 60.4% (95% CI: 50.8; 69.2), while the sensitivity was 49.4% (95% CI: 38.2; 60.6) for the cRDT. The pooled specificity of uRDT regardless of the reference test and the clinical presentation of participants was 98.6% (95% CI: 97.1; 99.4), and the pooled specificity of cRDT regardless of the reference test and the clinical presentation of participants was 99.3% (95% CI: 98.1; 99.7). When PCR was used as reference test the specificity of uRDT and cRDT was 97.5% (95% CI: 94.1; 98.9) and 98.2% (95% CI: 95.5; 99.3). Regardless of the reference test used, the sensitivity of Alere™ Ultra-sensitive Malaria Ag P. falciparum RDT in symptomatic patients was 72.1% (95%CI: 67.4; 76.4), while sensitivity of cRDT was 67.4% (95%CI: 57.6; 75.9).

Conclusion

Findings of the meta-analysis show that Alere™ Ultra-sensitive Malaria Ag P. falciparum RDT compared to cRDT performed in the same field conditions has higher sensitivity but lower specificity although the difference is not statistically significant.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-03783-2.

Teratogen update: Malaria in pregnancy and the use of antimalarial drugs in the first trimester

Malaria is a particular problem in pregnancy because of enhanced sensitivity, the possibility of placental malaria, and adverse effects on pregnancy outcome. Artemisinin-containing combination therapies (ACTs) are the most effective antimalarials known. WHO recommends 7-day quinine therapy for uncomplicated Plasmodium falciparum malaria in the first trimester despite the superior tolerability and efficacy of 3-day ACT regimens because artemisinins caused embryolethality and/or cardiovascular malformations at relatively low doses in rats, rabbits, and monkeys. The developmental toxicity of artesunate, artemether, and DHA were similar in rats but artesunate was embryotoxic at lower doses in rabbits (5 mg/kg/day) than artemether (no effect level = 25 mg/kg/day). In clinical studies in Africa, treatment with artemether-lumefantrine in the first trimester was observed to be highly efficacious and the miscarriage rate (≤3.1%) was similar to no antimalarial treatment (2.6%). When data from the first-trimester use of largely artesunate-based therapies in Thailand were pooled together, there was no difference in miscarriage rate compared to quinine. However, individually, artesunate-mefloquine was associated with a higher miscarriage rate (15/71 = 21%) compared to other artemisinin-based therapies including 7-day artesunate + clindamycin (2/50 = 4%) and quinine (92/842 = 11%). Thus, appropriate statistical comparisons of individual ACT groups are needed prior to assuming that they all have the same risk for developmental toxicity. Current limitations in the assessment of the safety of ACTs in the first trimester are a lack of exposures early in gestation (gestational weeks 6-7), limited postnatal evaluation for cardiovascular malformations, and the pooling of all ACTs for the assessment of risk.

Prevalence of placental malaria among asymptomatic pregnant women in Wolkite health center, Gurage zone, Southern Ethiopia

BACKGROUND

Placental malaria (PM) is a major public health problem associated with adverse pregnancy outcomes such as low birth weight (LBW), preterm delivery and maternal anemia. The present study is aimed to determine the prevalence of placental malaria among asymptomatic pregnant women in Wolkite health center, Gurage zone, Southern Ethiopia.

METHOD

Facility-based cross-sectional study was carried out from June 2019 to August 2019. A total of 230 pregnant women were involved in the study where socio-demographic data, medical and obstetric history were collected using pretested structured questionnaires. Blood samples were collected at delivery from maternal capillary, placenta and umbilical cord for the detection of malarial parasite. Maternal hematocrit was determined to screen for anemia.

RESULT

In this study, the prevalence of placental malaria, peripheral malaria and umbilical cord malaria was 3.9% (9/230), 15.2% (35/230) and 2.6% (6/230) respectively. Plasmodium falciparum and Plasmodium vivax were detected by microscopy. All babies with positive umbilical cord blood films were born from a mother with placental malaria. Maternal anemia was recorded in 58.3% of the women. In univariate analysis, placental malaria was significantly associated with LBW (p < 0.001) unlike parity and maternal anemia.

CONCLUSION

Placental malaria among asymptomatic pregnant women is low in Wolkite health centre, Gurage zone in Southern Ethiopia. Moreover, placental malaria was strongly associated with LBW. Thus, further strengthening the existing prevention and control activities and screening of asymptomatic pregnant women as part of routine antenatal care service is very essential.

Efficacy and tolerability of artemisinin-based and quinine-based treatments for uncomplicated falciparum malaria in pregnancy: a systematic review and individual patient data meta-analysis

BACKGROUND

Malaria in pregnancy affects both the mother and the fetus. However, evidence supporting treatment guidelines for uncomplicated (including asymptomatic) falciparum malaria in pregnant women is scarce and assessed in varied ways. We did a systematic literature review and individual patient data (IPD) meta-analysis to compare the efficacy and tolerability of different artemisinin-based or quinine-based treatments for malaria in pregnant women.

METHODS

We did a systematic review of interventional or observational cohort studies assessing the efficacy of artemisinin-based or quinine-based treatments in pregnancy. Seven databases (MEDLINE, Embase, Global Health, Cochrane Library, Scopus, Web of Science, and Literatura Latino Americana em Ciencias da Saude) and two clinical trial registries (International Clinical Trials Registry Platform and ClinicalTrials.gov) were searched. The final search was done on April 26, 2019. Studies that assessed PCR-corrected treatment efficacy in pregnancy with follow-up of 28 days or more were included. Investigators of identified studies were invited to share data from individual patients. The outcomes assessed included PCR-corrected efficacy, PCR-uncorrected efficacy, parasite clearance, fever clearance, gametocyte development, and acute adverse events. One-stage IPD meta-analysis using Cox and logistic regression with random-effects was done to estimate the risk factors associated with PCR-corrected treatment failure, using artemether-lumefantrine as the reference. This study is registered with PROSPERO, CRD42018104013.

FINDINGS

Of the 30 studies assessed, 19 were included, representing 92% of patients in the literature (4968 of 5360 episodes). Risk of PCR-corrected treatment failure was higher for the quinine monotherapy (n=244, adjusted hazard ratio [aHR] 6·11, 95% CI 2·57-14·54, p<0·0001) but lower for artesunate-amodiaquine (n=840, 0·27, 95% 0·14-0·52, p<0·0001), artesunate-mefloquine (n=1028, 0·56, 95% 0·34-0·94, p=0·03), and dihydroartemisinin-piperaquine (n=872, 0·35, 95% CI 0·18-0·68, p=0·002) than artemether-lumefantrine (n=1278) after adjustment for baseline asexual parasitaemia and parity. The risk of gametocyte carriage on day 7 was higher after quinine-based therapy than artemisinin-based treatment (adjusted odds ratio [OR] 7·38, 95% CI 2·29-23·82).

INTERPRETATION

Efficacy and tolerability of artemisinin-based combination therapies (ACTs) in pregnant women are better than quinine. The lower efficacy of artemether-lumefantrine compared with other ACTs might require dose optimisation.

FUNDING

The Bill & Melinda Gates Foundation, ExxonMobil Foundation, and the University of Oxford Clarendon Fund.

Pregnancy outcomes and risk of placental malaria after artemisinin-based and quinine-based treatment for uncomplicated falciparum malaria in pregnancy: a WorldWide Antimalarial Resistance Network systematic review and individual patient data meta-analysis

BACKGROUND

Malaria in pregnancy, including asymptomatic infection, has a detrimental impact on foetal development. Individual patient data (IPD) meta-analysis was conducted to compare the association between antimalarial treatments and adverse pregnancy outcomes, including placental malaria, accompanied with the gestational age at diagnosis of uncomplicated falciparum malaria infection.

METHODS

A systematic review and one-stage IPD meta-analysis of studies assessing the efficacy of artemisinin-based and quinine-based treatments for patent microscopic uncomplicated falciparum malaria infection (hereinafter uncomplicated falciparum malaria) in pregnancy was conducted. The risks of stillbirth (pregnancy loss at ≥ 28.0 weeks of gestation), moderate to late preterm birth (PTB, live birth between 32.0 and < 37.0 weeks), small for gestational age (SGA, birthweight of < 10th percentile), and placental malaria (defined as deposition of malaria pigment in the placenta with or without parasites) after different treatments of uncomplicated falciparum malaria were assessed by mixed-effects logistic regression, using artemether-lumefantrine, the most used antimalarial, as the reference standard. Registration PROSPERO: CRD42018104013.

RESULTS

Of the 22 eligible studies (n = 5015), IPD from16 studies were shared, representing 95.0% (n = 4765) of the women enrolled in literature. Malaria treatment in this pooled analysis mostly occurred in the second (68.4%, 3064/4501) or third trimester (31.6%, 1421/4501), with gestational age confirmed by ultrasound in 91.5% (4120/4503). Quinine (n = 184) and five commonly used artemisinin-based combination therapies (ACTs) were included: artemether-lumefantrine (n = 1087), artesunate-amodiaquine (n = 775), artesunate-mefloquine (n = 965), and dihydroartemisinin-piperaquine (n = 837). The overall pooled proportion of stillbirth was 1.1% (84/4361), PTB 10.0% (619/4131), SGA 32.3% (1007/3707), and placental malaria 80.1% (2543/3035), and there were no significant differences of considered outcomes by ACT. Higher parasitaemia before treatment was associated with a higher risk of SGA (adjusted odds ratio [aOR] 1.14 per 10-fold increase, 95% confidence interval [CI] 1.03 to 1.26, p = 0.009) and deposition of malaria pigment in the placenta (aOR 1.67 per 10-fold increase, 95% CI 1.42 to 1.96, p < 0.001).

CONCLUSIONS

The risks of stillbirth, PTB, SGA, and placental malaria were not different between the commonly used ACTs. The risk of SGA was high among pregnant women infected with falciparum malaria despite treatment with highly effective drugs. Reduction of malaria-associated adverse birth outcomes requires effective prevention in pregnant women.

Optimal Duration of Follow-up for Assessing Antimalarial Efficacy in Pregnancy: A Retrospective Analysis of a Cohort Followed Up Until Delivery on the Thailand-Myanmar Border

Background

Follow-up for 28–42 days is recommended by the World Health Organization to assess antimalarial drug efficacy for nonpregnant populations. This study aimed to determine the optimal duration for pregnant women, as no specific guidance currently exists.

Methods

The distributions of time to recrudescence (treatment failure), confirmed by polymerase chain reaction genotyping for different antimalarial drugs in pregnancy, were analyzed by accelerated failure time models using secondary data on microscopically confirmed recurrent falciparum malaria collected in prospective studies on the Thailand–Myanmar border between 1994 and 2010.

Results

Of 946 paired isolates from 703 women, the median duration of follow-up for each genotyped recurrence (interquartile range) was 129 (83–174) days, with 429 polymerase chain reaction–confirmed recrudescent. Five different treatments were evaluated, and 382 Plasmodium falciparum recrudescences were identified as eligible. With log-logistic models adjusted for baseline parasitemia, the predicted cumulative proportions of all the recrudescences that were detected by 28 days were 70% (95% confidence interval [CI], 65%–74%) for quinine monotherapy (n = 295), 66% (95% CI, 53%–76%) for artesunate monotherapy (n = 43), 62% (95% CI, 42%–79%) for artemether–lumefantrine (AL; n = 19), 46% (95% CI, 26%–67%) for artesunate with clindamycin (n = 19), and 34% (95% CI, 11%–67%) for dihydroartemisinin–piperaquine (DP; n = 6). Corresponding figures by day 42 were 89% (95% CI, 77%–95%) for AL and 71% (95% CI, 38%–91%) for DP. Follow-up for 63 days was predicted to detect ≥95% of all recrudescence, except for DP.

Conclusions

In low-transmission settings, antimalarial drug efficacy assessments in pregnancy require longer follow-up than for nonpregnant populations.

Sub-microscopic Plasmodium falciparum infections in matched peripheral, placental and umbilical cord blood samples from asymptomatic Congolese women at delivery

In malaria-endemic areas, most pregnant women are susceptible to asymptomatic Plasmodium falciparum infections. We present here the results of a cross-sectional study conducted in Madibou, a southern district of Brazzaville in the Republic of Congo, between March 2014 and April 2015. The main aim was to characterize P. falciparum infections. Blood samples corresponding to peripheral, placental and cord from 370 asymptomatic malaria women at delivery were diagnosed for plasmodium infection by thick blood smears (microscopic infection). Sub-microscopic infection was detected by PCR, using the MSP-2 gene as marker. Microscopic infections were detected in peripheral, placental and cord blood samples with a prevalence of respectively 7.3% (27/370), 2.7% (10/370) and 0%. The negative samples were submitted to sub-microscopic detection, with respective prevalence of 25.4% (87/343), 16.7% (60/360) and 9.4% (35/370) (P < 0.001). We further investigated the genetic diversity of the parasite by characterizing MSP2 allelic families 3D7 (24 distinct alleles) and FC27 (20 distinct alleles). The total number of alleles for these two families were 31, 25 and 19 in peripheral, placental and cord samples respectively. The 3D7 MSP-2 was the predominant allelic family. The multiplicity of infections (MOI) in peripheral (mean 1.4 ± 0.01; range 1-4), placental (mean 1.2 ± 0.01; range 1-3) and cord samples (1.4 ± 0.01; range 1-3) were similar (P = 0.9) and are unaffected by age, gravidity or sulfadoxine-pyrimethamine. These results shown a high prevalence of sub-microscopic infection and a high genetic diversity of Plasmodium falciparum strains in Congo. Age, gravidity and doses of preventive treatment based on sulfadoxine-pyrimethamine do not interfere with the multiplicity of infections.

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.

Matched Placental and Circulating Plasmodium falciparum Parasites are Genetically Homologous at the var2csa ID1-DBL2X Locus by Deep Sequencing

In pregnancy-associated malaria, infected erythrocytes accumulate in the placenta. It is unclear if in polyclonal infections this results in distinct peripheral and placental parasite populations. We used long amplicon deep sequencing of Plasmodium falciparum var2csa ID1-DBL2X from 15 matched peripheral and placental samples collected at delivery from a high transmission area to determine genetic homology. Despite substantial sequence variation and detecting 23 haplotypes, the matched pairs mostly contained the same genetic variants, with 11 pairs sharing 100% of their variants, whereas others showed some heterogeneity. Thus, at delivery, peripheral and placental parasites appear to intermix and placental genotypes can be inferred through peripheral sampling.

Advancing Global Health through Development and Clinical Trials Partnerships: A Randomized, Placebo-Controlled, Double-Blind Assessment of Safety, Tolerability, and Immunogenicity of PfSPZ Vaccine for Malaria in Healthy Equatoguinean Men

Equatorial Guinea (EG) has implemented a successful malaria control program on Bioko Island. A highly effective vaccine would be an ideal complement to this effort and could lead to halting transmission and eliminating malaria. Sanaria® PfSPZ Vaccine (Plasmodium falciparum sporozoite Vaccine) is being developed for this purpose. To begin the process of establishing the efficacy of and implementing a PfSPZ Vaccine mass vaccination program in EG, we decided to conduct a series of clinical trials of PfSPZ Vaccine on Bioko Island. Because no clinical trial had ever been conducted in EG, we first successfully established the ethical, regulatory, quality, and clinical foundation for conducting trials. We now report the safety, tolerability, and immunogenicity results of the first clinical trial in the history of the country. Thirty adult males were randomized in the ratio 2:1 to receive three doses of 2.7 × 105 PfSPZ of PfSPZ Vaccine (N = 20) or normal saline placebo (N = 10) by direct venous inoculation at 8-week intervals. The vaccine was safe and well tolerated. Seventy percent, 65%, and 45% of vaccinees developed antibodies to Plasmodium falciparum (Pf) circumsporozoite protein (PfCSP) by enzyme-linked immunosorbent assay, PfSPZ by automated immunofluorescence assay, and PfSPZ by inhibition of sporozoite invasion assay, respectively. Antibody responses were significantly lower than responses in U.S. adults who received the same dosage regimen, but not significantly different than responses in young adult Malians. Based on these results, a clinical trial enrolling 135 subjects aged 6 months to 65 years has been initiated in EG; it includes PfSPZ Vaccine and first assessment in Africa of PfSPZ-CVac. ClinicalTrials.gov identifier: NCT02418962.

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.

Systematic literature review and meta-analysis of the efficacy of artemisinin-based and quinine-based treatments for uncomplicated falciparum malaria in pregnancy: methodological challenges

Background

There is no agreed standard method to assess the efficacy of anti-malarials for uncomplicated falciparum in pregnancy despite an increased risk of adverse outcomes for the mother and the fetus. The aim of this review is to present the currently available evidence from both observational and interventional cohort studies on anti-malarial efficacy in pregnancy and summarize the variability of assessment and reporting found in the review process.

Methods

Efficacy methodology and assessment of artemisinin-based treatments (ABT) and quinine-based treatments (QBT) were reviewed systematically using seven databases and two clinical trial registries (protocol registration—PROSPERO: CRD42017054808). Pregnant women in all trimesters with parasitologically confirmed uncomplicated falciparum malaria were included irrespective of symptoms. This review attempted to re-calculate proportions of treatment success applying the same definition as the standard WHO methodology for non-pregnant populations. Aggregated data meta-analyses using data from randomized control trials (RCTs) comparing different treatments were performed by random effects model.

Results

A total of 48 eligible efficacy studies were identified including 7279 treated Plasmodium falciparum episodes. While polymerase chain reaction (PCR) was used in 24 studies for differentiating recurrence, the assessment and reporting of treatment efficacy was heterogeneous. When the same definition could be applied, PCR-corrected treatment failure of ≥ 10% at any time points was observed in 3/30 ABT and 3/7 QBT arms. Ten RCTs compared different combinations of ABT but there was a maximum of two published RCTs with PCR-corrected outcomes for each comparison. Five RCTs compared ABT and QBT. Overall, the risk of treatment failure was significantly lower in ABT than in QBT (risk ratio 0.22, 95% confidence interval 0.07–0.63), although the actual drug combinations and outcome endpoints were different. First trimester women were included in 12 studies none of which were RCTs of ABT.

Conclusions

Efficacy studies in pregnancy are not only limited in number but use varied methodological assessments. In five RCTs with comparable methodology, ABT resulted in higher efficacy than QBT in the second and third trimester of pregnancy. Individual patient data meta-analysis can include data from observational cohort studies and could overcome some of the limitations of the current assessment given the paucity of data in this vulnerable group.

Electronic supplementary material

The online version of this article (10.1186/s12936-017-2135-y) contains supplementary material, which is available to authorized users.

Plasmodium falciparum genotypes in matched peripheral, placental and umbilical cord blood in an area characterised by unstable malaria transmission in eastern Sudan

Background

There are few published studies on Plasmodium falciparum genotypes in peripheral, placental and umbilical cord blood in areas characterised by unstable malaria transmission.

Method

A cross-sectional study was conducted to investigate P. falciparum genotypes in matched peripheral, placental and umbilical cord blood in eastern Sudan. Thick blood smears and P. falciparum merozoite surface protein 1 (MSP1) and 2 (MSP2) genes as polymorphic markers in polymerase chain reactions were investigated in 3 kinds of samples of 153 pregnant women at delivery.

Results

There was no significant difference in the prevalence of blood film-detected P. falciparum in which 5 (3.3%), 7 (4.6%) and 3 (2.0%) (P = 0.437) of the 153 samples were determined to be P. falciparum-positive by microscopy for maternal peripheral, placental and cord blood samples, respectively.

Out of these 145 samples, 24 (16.6%), 39 (26.9%) and 24 (16.6%) (P = 0.039) of the peripheral, placental and cord samples, respectively, had submicroscopic parasitaemia (blood films were negative). There was no association between submicroscopic parasitaemia and age or parity.

RO33 and K1 (MSP1 alleles) were detected in 21/29 (72.4%), 42/46 (85.7%), 26/27 (92.2%) and 6/29 (20.6), 16/46 (32.6) and 0(0) (P < 0.001) of the maternal, placental and cord samples, respectively. MAD20 was not detected in any of the samples.

While the 3D7/IC1 allele was detected in 12 (41.3%), 30 (65.2%) and 4 (14.8%) (P < 0.001) of the peripheral, placental and cord samples, respectively, the FC (MSP2) allele was detected in only the 6 (20.6) placental samples. Multi-clonal infection was detected in 10 (34.4), 27 (58.6) and 3 (11.1) (P < 0.001) of the maternal placental and cord samples, respectively.

Conclusion

Compared with the peripheral and cord samples, placental samples had a higher prevalence of submicroscopic parasitaemia. MSP1 alleles were predominant in the cord, while MSP2 alleles were predominant in the placental samples, which had a significant higher multiplicity of the infection.