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Background: GMZ2 is a fusion protein of Plasmodium falciparum merozoite surface protein 3 (MSP3) and glutamate rich protein (GLURP) that mediates an immune response against the blood stage of the parasite. Two previous phase I clinical trials, one in nai&vuml;e European adults and one in malaria-exposed Gabonese adults showed that GMZ2 was well tolerated and immunogenic. Here, we present data on safety and immunogenicity of GMZ2 in one to five year old Gabonese children, a target population for future malaria vaccine efficacy trials. Methodology/Principal Findings: Thirty children one to five years of age were randomized to receive three doses of either 30 mg or 100 mg of GMZ2, or rabies vaccine. GMZ2, adjuvanted in aluminum hydroxide, was administered on Days 0, 28 and 56. All participants received a full course of their respective vaccination and were followed up for one year. Both 30 mg and 100 mg GMZ2 vaccine doses were well tolerated and induced antibodies and memory B-cells against GMZ2 as well as its antigenic constituents MSP3 and GLURP. After three doses of vaccine, the geometric mean concentration of antibodies to GMZ2 was 19-fold (95%CI: 11,34) higher in the 30 mg GMZ2 group than in the rabies vaccine controls, and 16-fold (7,36) higher in the 100 mg GMZ2 group than the rabies group. Geometric mean concentration of antibodies to MSP3 was 2.7-fold (1.6,4.6) higher in the 30 mg group than in the rabies group and 3.8-fold (1.5,9.6) higher in the 100 mg group. Memory B-cells against GMZ2 developed in both GMZ2 vaccinated groups. Conclusions/Significance: Both 30 mg as well as 100 mg intramuscular GMZ2 are immunogenic, well tolerated, and safe in young, malaria-exposed Gabonese children. This result confirms previous findings in nai&vuml;e and malaria-exposed adults and supports further clinical development of GMZ2. Trial Registration: ClinicalTrials.gov NCT00703066 [ABSTRACT FROM AUTHOR]

We measured natural killer (NK) cell cytotoxicity and cortisol and prolactin concentrations in peripheral venous blood samples obtained from pregnant Gabonese women at the time of delivery. The NK cell­mediated cytotoxicity against Plasmodium falciparum­infected erythrocytes in vitro was lower in samples obtained from primiparous women than in samples obtained from multiparous women; cortisol concentrations were significantly higher in primiparous women than in multiparous women, and prolactin concentrations were significantly lower. The highest cortisol concentrations were found in the plasma of P. falciparum­infected primiparous women. A positive correlation was found between cortisol concentration and parasite load; an inverse correlation was found between the magnitude of the NK cell cytolytic effect and cortisol production. A positive correlation was found between this effect and prolactin production. Thus, depressed NK cell cytotoxicity against P. falciparum­infected erythrocytes is correlated with high cortisol concentrations and may contribute to increased susceptibility to malaria during pregnancy. [ABSTRACT FROM AUTHOR]

BACKGROUND: Parenteral artesunate is recommended as first-line therapy for severe malaria. While its efficacy is firmly established, data on safety are still incomplete. Delayed hemolysis has been described in hyperparasitemic nonimmune travelers, but it is unknown if African children are equally at risk. METHODS: Children aged 6 to 120 months with severe malaria were followed up after treatment with parenteral artesunate in Lambaréné, Gabon, and Kumasi, Ghana. The primary outcome was incidence of delayed hemolysis on day 14. RESULTS: In total, 72 children contributed complete data sets necessary for primary outcome assessment. Delayed hemolysis was detected in 5 children (7%), with 1 child reaching a nadir in hemoglobin of 2.8 g/dL. Patients with delayed hemolysis had higher parasite counts on admission (geometric mean parasite densities (GMPD) 306 968/uL vs 92 642/uL, P = .028) and were younger (median age: 24 months vs 43 months, P = .046) than the rest of the cohort. No correlation with sickle cell trait or glucose-6-phosphate-dehydrogenase deficiency was observed. CONCLUSIONS: Delayed hemolysis is a frequent and relevant complication in hyperparasitemic African children treated with parenteral artesunate for severe malaria. Physicians should be aware of this complication and consider prolonged follow-up. CLINICAL TRIALS REGISTRATION: Pan-African Clinical Trials Registry: PACTR201102000277177 (www.pactr.org). [ABSTRACT FROM AUTHOR]

Background. Parenteral artesunate is recommended as first-line therapy for severe malaria. While its efficacy is firmly established, data on safety are still incomplete. Delayed hemolysis has been described in hyperparasitemic nonimmune travelers, but it is unknown if African children are equally at risk.Methods. Children aged 6 to 120 months with severe malaria were followed up after treatment with parenteral artesunate in Lambaréné, Gabon, and Kumasi, Ghana. The primary outcome was incidence of delayed hemolysis on day 14.Results. In total, 72 children contributed complete data sets necessary for primary outcome assessment. Delayed hemolysis was detected in 5 children (7%), with 1 child reaching a nadir in hemoglobin of 2.8 g/dL. Patients with delayed hemolysis had higher parasite counts on admission (geometric mean parasite densities (GMPD) 306 968/µL vs 92 642/µL, P = .028) and were younger (median age: 24 months vs 43 months, P = .046) than the rest of the cohort. No correlation with sickle cell trait or glucose-6-phosphate-dehydrogenase deficiency was observed.Conclusions. Delayed hemolysis is a frequent and relevant complication in hyperparasitemic African children treated with parenteral artesunate for severe malaria. Physicians should be aware of this complication and consider prolonged follow-up.Clinical Trials Registration. Pan-African Clinical Trials Registry: PACTR201102000277177 (www.pactr.org). [ABSTRACT FROM AUTHOR]

Background. We compared a conventional empirically derived regimen with a simplified regimen for parenteral artesunate in severe malaria. Methods. This was a randomized, double-blind, placebo-controlled comparison to assess the noninferiority of a simplified 3-dose regimen (given at 0, 24, and 48 hours) compared with the conventional 5-dose regimen of intravenous artesunate (given at 0, 12, 24, 48, and 72 hours) in African children with Plasmodium falciparum malaria with a prespecified delta of 0.2. The total dose of artesunate in each group was 12 mg/kg. The primary end point was the proportion of children clearing ≥99% of their admission parasitemia at 24 hours. Safety data, secondary efficacy end points, and pharmacokinetics were also analyzed. Results. In 171 children (per protocol), 78% of the recipients (95% confidence interval [CI], 69%-87%) in the 3-dose group achieved ≥99% parasite clearance 24 hours after the start of treatment, compared with 85% (95% CI, 77%-93%) of those receiving the conventional regimen (treatment difference, 27.2%; 95% CI, 218.9% to 4.4%). Dihydroartemisinin was cleared slightly more slowly in those children receiving the higher 3-dose regimen (7.4 vs 8.8 L/h for a 13-kg child; P 5 .008). Conclusions. Pharmacodynamic analysis suggests that 3 doses of artesunate were not inferior to 5 doses for the treatment of severe malaria in children. [ABSTRACT FROM AUTHOR]

Background. Plasmodium falciparum malaria accounts for >1 million deaths annually, mostly among young children in sub-Saharan Africa. Identifying those individuals who are likely to die is crucial. Several factors have been independently associated with death. Because malaria is a systemic disease, a quantitative score combining such risk factors may be superior. Methods. We used both forward and backward stepwise logistic regression to select the best predictors of death, as evaluated for 23,890 African children with severe P. falciparum malaria. The study was conducted from December 2000 through May 2005 in 6 hospital-based research units (in Banjul in the Gambia, Blantyre in Malawi, Kilifi in Kenya, Kumasi in Ghana, and Lambaréné and Libreville in Gabon) in a network established to study severe malaria in African children (ie, the SMAC Network). Results. The Lambaréné Organ Dysfunction Score (LODS) combines 3 variables: coma, prostration, and deep breathing. A LODS >0 (odd ratio, 9.6; 95% confidence interval, 8.0-11.4) has 85% sensitivity to predict death, and a LODS <3 is highly (98%) specific for survival. Conclusions. The LODS is a simple clinical predictor of fatal malaria in African children. This score provides accurate and rapid identification of children needing either referral or increased attention. [ABSTRACT FROM AUTHOR]

Among the Plasmodium species that infect humans, P. falciparum has been largely studied in malaria endemic areas. However, P. malariae infection is less documented among the human population. This study aimed to monitor the prevalence and distribution of P. malariae in Southern Benin. A cross-sectional survey was conducted in rural localities in the Ouidah–Kpomasse–Tori Bossito (OKT) health district in Southern Benin from June to October 2019. Socio-demographic data were collected using a questionnaire, while malaria infection data were obtained on the one hand by microscopy diagnosis and, on the other, by nested polymerase chain reaction (PCR). Based on microscopy, the prevalence of P. malariae mono-infection and coinfection of P. falciparum, P. malariae was respectively 2.3% and 1.2% in the OKT health district. This prevalence was higher (P < 0.01) than that reported by Damien et al. (2010) 10 years ago in the same study area with 0.7% and 0.3% of P. malariae and P. falciparum/P. malariae, respectively. Based on PCR analysis, P. malariae prevalence was 14.1%, including 5.2% of mono-infection and 8.9% of mixed infection with P. falciparum. Sub-microscopic Plasmodium infections were high (30.6%) and more pronounced in older participants (>20 years). The present study revealed that P. malariae increased in the OKT health district with a high prevalence of submicroscopic infection. Since our results provide valuable evidence of increasing P. malariae infection, the National Malaria Control Programs (NMCPs) must consider P. malariae when designing future measures for effective control and malaria treatment. [ABSTRACT FROM AUTHOR]

Our current knowledge of the clinical burden, biology, and transmission of Plasmodium malariae is extremely scarce. To start addressing some of those questions, we experimentally infected Anopheles gambiae mosquitoes with fresh P. malariae isolates obtained from asymptomatic individuals in Lambaréné, Gabon. The proportion of mosquitoes infected via direct membrane feeding assay with either P. malariae monoinfections (16% [19 of 121]) or coinfections (28% [31 of 112]) was higher after serum replacement than in parallel groups without serum replacement (4% [4 of 102] and 4% [2 of 45], respectively; P < .01). Our results show that isolates from asymptomatic carriers can be used for experimental studies of P. malariae transmission. [ABSTRACT FROM AUTHOR]

Abstract: Emerging drug resistance in Plasmodium falciparum and its rapid spread in endemic countries have made the quest for new antimalarials a research priority. Tetracycline and its derivatives are well-established compounds for combination with faster-acting drugs in the current practice of malaria treatment. Tigecycline is the first marketed derivative of a new class of tetracycline antibiotics. Its altered structure leads to enhanced activity against bacteria and may also be associated with improved antimalarial activity. Using the histidine-rich protein 2 (HRP2) drug sensitivity assay, we determined the geometric mean 50% inhibitory concentrations (IC50) of tigecycline in culture-adapted strains as well as in 23 clinical P. falciparum isolates from Lambaréné, Gabon. These values were compared with other tetracyclines as well as with clindamycin. Assays with 3 days and 6 days of incubation were evaluated to explore the impact of delayed parasite death on drug activity. IC50 values in clinical isolates after 6 days of incubation were 160.0nM [95% confidence interval (CI) 114.6–223.4nM] for tigecycline, 739.4nM (445.9–1226.1nM) for doxycycline and 9.2nM (95% CI 6.6–12.9nM) for clindamycin. Tigecycline was found to act faster against plasmodia than any of the other antibiotics tested. This study demonstrates the potential of tetracycline derivatives in the development of improved antimalarials. [Copyright &y& Elsevier]

Hepatitis B virus (HBV) infection remains one of the major neglected health issues worldwide. In sub-Saharan Africa (SSA), HBV endemicity is high, with more than 8% of the population being chronic HBV carriers. Recently, WHO recommended that all infants should receive their first dose of the HBV vaccine as soon as possible after birth. Unfortunately, the incorporation of a birth dose of HBV in the expanded programme immunization (EPI) has not occurred in the majority of countries in SSA. From April to September 2017, a cross-sectional survey was conducted in two vaccine units located in southern Benin. We assessed the sustained anti-HBs antibody response in infants induced by a standard scheme of 3 doses of HBV vaccination (6, 10, 14 weeks) in comparison to a scheme of 4 doses with a birth dose included (0, 6, 10, 14 weeks). Blood samples were systematically collected in the first 140 children aged 9 months and their mothers who had consented to participate for the detection of HBs antigen and the quantification of anti-HBs antibodies. The prevalence of HBV infection among infants and mothers was 2.2% and 7.1%, respectively. Infants who received 4 doses of HBV vaccine had a significantly higher level of anti-HBs antibody than those who received 3 doses of vaccine (557.9 UI/L vs. 386.9 UI/L, respectively, P = 0.03). We also showed that the scheme of 4 doses was associated with a significantly higher sustained protective response in comparison to the scheme of 3 doses (aOR 2.49, 95% CI 1.03–6.03, P = 0.04). This result provides further evidence of the importance of administering HBV vaccine at birth, but also highlights the importance for the prevention of vertical transmissions. Additional studies are needed to better establish the cost-effectiveness of such a 4 doses immunization strategy before implementing the HBV vaccination at birth in the EPI. [ABSTRACT FROM AUTHOR]

Background Malaria in pregnancy has major impacts on mother and child health. To complement existing interventions, such as intermittent preventive treatment and use of impregnated bed nets, we developed a malaria vaccine candidate with the aim of reducing sequestration of asexual "blood-stage" parasites in the placenta, the major virulence mechanism. Methods The vaccine candidate PAMVAC is based on a recombinant fragment of VAR2CSA, the Plasmodium falciparum protein responsible for binding to the placenta via chondroitin sulfate A (CSA). Healthy, adult malaria-naive volunteers were immunized with 3 intramuscular injections of 20 μg (n = 9) or 50 μg (n = 27) PAMVAC, adjuvanted with Alhydrogel or glucopyranosyl lipid adjuvant in stable emulsion (GLA-SE) or in a liposomal formulation with QS21 (GLA-LSQ). Allocation was random and double blind. The vaccine was given every 4 weeks. Volunteers were observed for 6 months following last immunization. Results All PAMVAC formulations were safe and well tolerated. A total of 262 adverse events (AEs) occurred, 94 (10 grade 2 and 2 grade 3) at least possibly related to the vaccine. No serious AEs occurred. Distribution and severity of AEs were similar in all arms. PAMVAC was immunogenic in all participants. PAMVAC-specific antibody levels were highest with PAMVAC-GLA-SE. The antibodies inhibited binding of VAR2CSA expressing P. falciparum -infected erythrocytes to CSA in a standardized functional assay. Conclusions PAMVAC formulated with Alhydrogel or GLA-based adjuvants was safe, well tolerated, and induced functionally active antibodies. Next, PAMVAC will be assessed in women before first pregnancies in an endemic area. Clinical Trials Registration EudraCT 2015-001827-21; ClinicalTrials.gov NCT02647489. [ABSTRACT FROM AUTHOR]

Background Pregnant women are more susceptible to Plasmodium falciparum than before pregnancy, and infection has consequences for both mother and offspring. The World Health Organization recommends that pregnant woman in areas of transmission receive intermittent preventive treatment (IPTp) starting in the second trimester. Consequently, women are not protected during the first trimester, although P. falciparum infections are both frequent and harmful. Methods A cohort of nulligravid women was followed up during subsequent pregnancy. Malaria was diagnosed by means of microscopy and polymerase chain reaction. Parasites were genotyped at polymorphic loci. Results Among 275 nulligravidae enrolled, 68 women became pregnant and were followed up during pregnancy. Before pregnancy, P. falciparum prevalence rates were 15% by microscopy and 66% by polymerase chain reaction. Microscopic infection rates increased to 29% until IPTp administration, and their density increased by 20-fold. Conversely, submicroscopic infection rates decreased. After IPTp administration, all types of infections decreased, but they increased again late in pregnancy. The risk of infection during pregnancy was higher in women with a microscopic (odds ratio, 6.5; P =.047) or submicroscopic (3.06; P =.05) infection before pregnancy and was not related to the season of occurrence. Most infections during pregnancy were persistent infections acquired before pregnancy. Conclusions Microscopic and submicroscopic malaria infections were frequent in nulligravid women from south Benin. During the first trimester of pregnancy, microscopic infections were more frequent, with a higher parasite density, and mainly derived from parasites infecting the woman before conception. Preventive strategies targeting nonpregnant women with a desire for conception need to be designed. [ABSTRACT FROM AUTHOR]

Background: The clinical development of a single encounter treatment for uncomplicated malaria has the potential to significantly improve the effectiveness of antimalarials. Exploratory data suggested that the combination of artefenomel and piperaquine phosphate (PQP) has the potential to achieve satisfactory cure rates as a single dose therapy. The primary objective of the study was to determine whether a single dose of artefenomel (800 mg) plus PQP in ascending doses is an efficacious treatment for uncomplicated Plasmodium falciparum malaria in the 'target' population of children ≤ 5 years of age in Africa as well as Asian patients of all ages.Methods: Patients in six African countries and in Vietnam were randomised to treatment with follow-up for 42-63 days. Efficacy, tolerability, safety and pharmacokinetics were assessed. Additional key objectives were to characterise the exposure-response relationship for polymerase chain reaction (PCR)-adjusted adequate clinical and parasitological response at day 28 post-dose (ACPR28) and to further investigate Kelch13 mutations. Patients in Africa (n = 355) and Vietnam (n = 82) were included, with 85% of the total population being children < 5 years of age.Results: ACPR28 in the per protocol population (95% confidence interval) was 70.8% (61.13-79.19), 68.4% (59.13-76.66) and 78.6% (70.09-85.67) for doses of 800 mg artefenomel with 640 mg, 960 mg and 1440 mg of PQP respectively. ACPR28 was lower in Vietnamese than in African patients (66.2%; 54.55-76.62 and 74.5%; 68.81-79.68) respectively. Within the African population, efficacy was lowest in the youngest age group of ≥ 0.5 to ≤ 2 years, 52.7% (38.80-66.35). Initial parasite clearance was twice as long in Vietnam than in Africa. Within Vietnam, the frequency of the Kelch13 mutation was 70.1% and was clearly associated with parasite clearance half-life (PCt1/2). The most significant tolerability finding was vomiting (28.8%).Conclusions: In this first clinical trial evaluating a single encounter antimalarial therapy, none of the treatment arms reached the target efficacy of > 95% PCR-adjusted ACPR at day 28. Achieving very high efficacy following single dose treatment is challenging, since > 95% of the population must have sufficient concentrations to achieve cure across a range of parasite sensitivities and baseline parasitaemia levels. While challenging, the development of tools suitable for deployment as single encounter curative treatments for adults and children in Africa and to support elimination strategies remains a key development goal.Trial Registration: ClinicalTrials.gov, NCT02083380 . Registered on 7 March 2014. [ABSTRACT FROM AUTHOR]

Background The antigen VAR2CSA plays a pivotal role in the pathophysiology of pregnancy-associated malaria (PAM) caused by Plasmodium falciparum . A VAR2CSA-based vaccine candidate, PAMVAC, is under development by an EU-funded multi-country consortium (PlacMalVac project). As part of PAMVAC's clinical development, we quantified naturally acquired vaccine antigen-specific memory B and T cell responses in Beninese primigravidae recruited at the beginning of pregnancy and followed up to delivery and beyond. Methods Clinical and parasitological histories were compiled from monthly clinic visits. On 4 occasions (first and fifth month of pregnancy, delivery, 6 months post-delivery) peripheral blood mononuclear cells were isolated for in vitro assays. PAMVAC-specific memory B cells as well as those specific for a PAM unrelated P. falciparum antigen (PfEMP1-CIDR1a) and for tetanus toxoid were quantified by ELISpot. Memory T cell responses were assessed by quantifying cytokines (IL-5, IL-6, IL-10, IL-13, IFN-γ, TNF-α) in supernatants of cells stimulated in vitro either with PAMVAC, or mitogen (PHA). Results Both tetanus toxoid- and PAMVAC-specific memory B cell frequencies increased to reach peak levels in the 5th month and at delivery, respectively and persisted post-delivery. The frequency of CIDR1a-specific memory B cells was stable during pregnancy, but declined post-delivery. The cumulated prevalence of infection with P. falciparum during pregnancy was 61% by microscopy. In women with a history of such infections, a significantly higher frequency of PAMVAC-specific memory B cells was observed at delivery. PAMVAC-specific pro-inflammatory (IFN-γ, TNF) responses tended to be higher at delivery in those with a history of infection. Mitogen-induced IL-5/IL-13 responses were significantly enhanced in the same women. Conclusions PAMVAC-specific memory B cells are induced during first pregnancies and are maintained post-delivery. Women with a T helper cell profile biased towards production of Th2-type cytokines have a greater risk of infection with P. falciparum. [ABSTRACT FROM AUTHOR]

Background: Transmission of malaria from man to mosquito depends on the presence of gametocytes, the sexual stage of Plasmodium parasites in the infected host. Naturally acquired antibodies against gametocytes exist and may play a role in controlling transmission by limiting the gametocyte development in the circulation or by interrupting gamete development and fertilization in the mosquito following ingestion. So far, most studies on antibody responses to sexual stage antigens have focused on a subset of gametocyte-surface antigens, even though inhibitory Ab responses to other gametocyte antigens might also play a role in controlling gametocyte density and fertility. Limited information is available on natural antibody response to the surfaces of gametocyte-infected erythrocytes. Methods: Ab responses to surface antigens of erythrocytes infected by in vitro differentiated Plasmodium falciparum mature gametocytes were investigated in sera of semi-immune adults and malaria-exposed children. In addition, the effect of immunization with GMZ2, a blood stage malaria vaccine candidate, and the effect of intestinal helminth infection on the development of immunity to gametocytes of P. falciparum was evaluated in malaria-exposed children and adults from Gabon. Serum samples from two Phase I clinical trials conducted in Gabon were analysed by microscopic and flow-cytometric immunofluorescence assay. Results: Adults had a higher Ab response compared to children. Ab reactivity was significantly higher after fixation and permeabilization of parasitized erythrocytes. Following vaccination with the malaria vaccine candidate GMZ2, anti-gametocyte Ab concentration decreased in adults compared to baseline. Ab response to whole asexual stage antigens had a significant but weak positive correlation to anti-gametocyte Ab responses in adults, but not in children. Children infected with Ascaris lumbricoides had a significantly higher anti-gametocyte Ab response compared to non-infected children. Conclusion: The current data suggest that antigens exposed on the gametocyte-infected red blood cells are recognized by serum antibodies from malaria-exposed children and semi-immune adults. This anti-gametocyte immune response may be influenced by natural exposure and vaccination. Modulation of the natural immune response to gametocytes by co-infecting parasites should be investigated further and may have an important impact on malaria control strategies. [ABSTRACT FROM AUTHOR]

Background GMZ2 is a recombinant protein malaria vaccine, comprising two blood-stage antigens of Plasmodium falciparum , glutamate-rich protein and merozoite surface protein 3. We assessed efficacy of GMZ2 in children in Burkina Faso, Gabon, Ghana and Uganda. Methods Children 12–60 months old were randomized to receive three injections of either 100 μg GMZ2 adjuvanted with aluminum hydroxide or a control vaccine (rabies) four weeks apart and were followed up for six months to measure the incidence of malaria defined as fever or history of fever and a parasite density ⩾5000/μL. Results A cohort of 1849 children were randomized, 1735 received three doses of vaccine (868 GMZ2, 867 control-vaccine). There were 641 malaria episodes in the GMZ2/Alum group and 720 in the control group. In the ATP analysis, vaccine efficacy (VE), adjusted for age and site was 14% (95% confidence interval [CI]: 3.6%, 23%, p -value = 0.009). In the ITT analysis, age-adjusted VE was 11.3% (95% CI 2.5%, 19%, p -value = 0.013). VE was higher in older children. In GMZ2-vaccinated children, the incidence of malaria decreased with increasing vaccine-induced anti-GMZ2 IgG concentration. There were 32 cases of severe malaria (18 in the rabies vaccine group and 14 in the GMZ2 group), VE 27% (95% CI −44%, 63%). Conclusions GMZ2 is the first blood-stage malaria vaccine to be evaluated in a large multicenter trial. GMZ2 was well tolerated and immunogenic, and reduced the incidence of malaria, but efficacy would need to be substantially improved, using a more immunogenic formulation, for the vaccine to have a public health role. [ABSTRACT FROM AUTHOR]

Background: Chronic schistosomiasis is associated with T cell hypo-responsiveness and immunoregulatory mechanisms, including induction of regulatory T cells (Tregs). However, little is known about Treg functional capacity during human Schistosoma haematobium infection. Methodology: CD4+CD25hiFOXP3+ cells were characterized by flow cytometry and their function assessed by analysing total and Treg-depleted PBMC responses to schistosomal adult worm antigen (AWA), soluable egg antigen (SEA) and Bacillus Calmette-Guérin (BCG) in S. haematobium-infected Gabonese children before and 6 weeks after anthelmintic treatment. Cytokines responses (IFN-γ, IL-5, IL-10, IL-13, IL-17 and TNF) were integrated using Principal Component Analysis (PCA). Proliferation was measured by CFSE. Principal Findings: S. haematobium infection was associated with increased Treg frequencies, which decreased post-treatment. Cytokine responses clustered into two principal components reflecting regulatory and Th2-polarized (PC1) and pro-inflammatory and Th1-polarized (PC2) cytokine responses; both components increased post-treatment. Treg depletion resulted in increased PC1 and PC2 at both time-points. Proliferation on the other hand, showed no significant difference from pre- to post-treatment. Treg depletion resulted mostly in increased proliferative responses at the pre-treatment time-point only. Conclusions: Schistosoma-associated CD4+CD25hiFOXP3+Tregs exert a suppressive effect on both proliferation and cytokine production. Although Treg frequency decreases after praziquantel treatment, their suppressive capacity remains unaltered when considering cytokine production whereas their influence on proliferation weakens with treatment. [ABSTRACT FROM AUTHOR]

Background: Severe malaria may influence inner ear function, although this possibility has not been examined prospectively. In a retrospective analysis, hearing impairment was found in 9 of 23 patients with cerebral malaria. An objective method to quickly evaluate the function of the inner ear are the otoacoustic emissions. Negative transient otoacoustic emissions are associated with a threshold shift of 20 dB and above. Methods: This prospective multicenter study analyses otoacoustic emissions in patients with severe malaria up to the age of 10 years. In three study sites (Ghana, Gabon, Kenya) 144 patients with severe malaria and 108 control children were included. All malaria patients were treated with parental artesunate. Results: In the control group, 92.6 % (n = 108, 95 % confidence interval 86.19-6.2 %) passed otoacoustic emission screening. In malaria patients, 58.5 % (n = 94, malaria vs controls < 0.001, 95 % confidence interval 48.4-67.9 %) p passed otoacoustic emission screening at the baseline measurement. The value increased to 65.2 % (n = 66, p < 0.001, 95 % confidence interval 53.1-75.5 %) at follow up 14-28 days after diagnosis of malaria. The study population was divided into severe non-cerebral malaria and severe malaria with neurological symptoms (cerebral malaria). Whereas otoacoustic emissions in severe malaria improved to a passing percentage of 72.9 % (n = 48, 95 % confidence interval 59-83.4 %) at follow-up, the patients with cerebral malaria showed a drop in the passing percentage to 33 % (n = 18) 3-7 days after diagnosis. This shows a significant impairment in the cerebral malaria group ( = 0.012 at days 3-7, 95 % confidence interval 16.3-56.3 %; = 0.031 at day 14-28, 95 % p p confidence interval 24.5-66.3 %). Conclusion: The presented data show that 40 % of children have involvement of the inner ear early in severe malaria. In children, audiological screening after severe malaria infection is not currently recommended, but is worth investigating in larger studies. [ABSTRACT FROM AUTHOR]

Background: A main export market for chicken meat from industrialized countries is sub-Saharan Africa. We hypothesized that antibiotic resistant bacteria could be exported to developing countries through chicken meat trade. The objective was to investigate the occurrence and molecular types of ESBL-producing Enterobacteriaceae and Staphylococcus aureus in chicken meat in Gabon and to assess their dissemination among humans. Results: Frozen chicken meat samples imported from industrialized countries to Gabon (n = 151) were screened for ESBL-producing Enterobacteriaceae and S. aureus. Genotypes and resistance genes (SHV, TEM, CTX-M, CMY-2) of isolates from meat were compared with isolates derived from humans. The contamination rate per chicken part (i. e. leg, wing) with ESBL-producing Escherichia coli (ESBL E. coli, no other ESBL-producing Enterobacteriaceae were found) and S. aureus was 23% and 3%, respectively. The beta-lactamase CTX-M 1 was predominant in ESBL E. coli from meat samples but was not found in isolates from cases of human colonization or infection. S. aureus belonging to spa type t002 (multilocus sequence type ST5) were found both in chicken meat and humans. Conclusion: There is a risk to import ESBL E. coli to Gabon but molecular differences between isolates from humans and chicken meat argue against a further dissemination. No MRSA isolate was detected in imported chicken meat. [ABSTRACT FROM AUTHOR]

Background: Physicians depend on reliable information on the local epidemiology of infection and antibiotic resistance rates to guide empiric treatment in critically ill patients. As these data are scarce for Central Africa, we performed a retrospective analysis of microbiological findings from a secondary care hospital in Gabon. Methods: Microbiological reports from 2009 to 2012 were used to assess the non-susceptibility rates of the three most common isolates from six major types of infections (bloodstream, ear-eye-nose-throat, surgical site, skin and soft tissue, urinary tract and wound infection). Results: A high diversity of pathogens was found, but Staphylococcus aureus was predominant in the majority of infections. Overall, the three most prevalent pathogens in children were S. aureus (33.7%), Streptococcus pyogenes (8.1%) and Escherichia coli (4.5%) and in adults S. aureus (23.5%), E. coli (15.1%) and Klebsiella pneumoniae (7.4%). In total, 5.8% (n = 19) of all S. aureus isolates were methicillin resistant. The proportion of extended-spectrum beta-lactamase (ESBL) producing Enterobacteriaceae was 15.4% (n = 78), 49.4% of all K. pneumoniae were ESBL-producer (n = 42). Conclusion: The high diversity of potential pathogens and high resistance rates in Gram-negative bacteria challenge a rational empiric use of antibiotics. Countrywide continuous sentinel surveillance is therefore urgently needed. [ABSTRACT FROM AUTHOR]

Background. GMZ2 is a hybrid protein consisting of the N-terminal region of the glutamate-rich protein fused in frame to the C-terminal region of merozoite surface protein 3 (MSP3). GMZ2 formulated in Al(OH)3 has been tested in 3 published phase 1 clinical trials. The GMZ2/alum formulation showed good safety, tolerability, and immunogenicity, but whether antibodies elicited by vaccination are functional is not known.Methods. Serum samples prior to vaccination and 4 weeks after the last vaccination from the 3 clinical trials were used to perform a comparative assessment of biological activity against Plasmodium falciparum.Results. We showed that the maximum level of immunoglobulin G (IgG) antibodies obtained by GMZ2 vaccination is independent of ethnicity, time under malaria-exposure, and vaccine dose and that GMZ2 elicits high levels of functionally active IgG antibodies. Both, malaria-naive adults and malaria-exposed preschool children elicit vaccine-specific antibodies with broad inhibitory activity against geographically diverse P. falciparum isolates. Peptide-mapping studies of IgG subclass responses identified IgG3 against a peptide derived from MSP3 as the strongest predictor of antibody-dependent cellular inhibition.Conclusions. These findings suggest that GMZ2 adjuvanted in Al(OH)3 elicits high levels of specific and functional antibodies with the capacity to control parasite multiplication. [ABSTRACT FROM AUTHOR]

A response by Yamikani Chimalizeni, Kondwana Kawaza, and Mattias Duscha to a letter to the editor about their article on a simplified intravenous artesunate regimen for severe malaria in the previous issue.

An abstract of the article "Extended haematological follow-up after parenteral artesunate in African children with severe malaria," by Thierry Rolling, Dorothee Spahlinger, Saadou Issifou, Tsiri Agbeniyega, Peter G. Kremsner, Gerd D. Burchard, Benjamin Mordmueller, and Jakob P. Cramer is presented.

Abstract: Background: Helminth infections are highly prevalent in the tropics and may have an effect on immune responses to vaccines due to their immunomodulatory effect. The prevalence of helminth infections in young children, the target group for malaria and most other vaccines, is high. Therefore we assessed the influence of helminth infection on vaccine-induced immune responses in a phase I clinical trial of the malaria vaccine candidate GMZ2. Methods: Twenty Gabonese preschool-age children were vaccinated with GMZ2, a blood stage malaria vaccine candidate. Humoral immune response against the vaccine antigens and parasitological status were assessed. Vaccine-specific antibody concentrations and memory B-cell numbers were compared in worm infected and non-infected participants. Results: Antibody response to GMZ2 was 3.4-fold (95% confidence interval: 1.6, 7.4) higher in Trichuris trichiura negative subjects compared to positive participants, whereas immunoglobulin subclass distribution was similar. Memory B-cell response was moderately increased in T. trichiura negative individuals, although the difference was not significant. Conclusions: Future malaria vaccine development programs need to account for worm-mediated hyporesponsiveness of immune reactions. [Copyright &y& Elsevier]

Abstract: Little data is available on the epidemiology of Staphylococcus aureus in Africa. In the present study we aim at characterizing the population structure of S. aureus in healthy subjects from a rural and a semi-urban area in Lambaréné, Gabon as well as in hospital staff and inpatients. In total, 500 subjects were screened for S. aureus colonization of the nares, axillae and inguinal region. Overall, 146 (29%) were positive. We found 46 different spa types. The most frequent spa types were t084 (35%) and the agr II was the most prevalent subtype of the accessory gene regulator (56%, n =82). Five isolates (3%) were methicillin resistant S. aureus (MRSA). Carriage rates of S. aureus in Gabon are comparable to developed countries. MRSA is for the first time described and could pose a significant health threat in this region with limited access to microbiological laboratory facilities and to adequate antimicrobial agents. [Copyright &y& Elsevier]

Background: Antibodies play a central role in naturally acquired immunity against Plasmodium falciparum. Current assays to detect anti-plasmodial antibodies against native antigens within their cellular context are prone to bias and cannot be automated, although they provide important information about natural exposure and vaccine immunogenicity. A novel, cytometry-based workflow for quantitative detection of anti-plasmodial antibodies in human serum is presented. Methods: Fixed red blood cells (RBCs), infected with late stages of P. falciparum were utilized to detect malaria-specific antibodies by flow cytometry with subsequent automated data analysis. Available methods for data-driven analysis of cytometry data were assessed and a new overlap subtraction algorithm (OSA) based on open source software was developed. The complete workflow was evaluated using sera from two GMZ2 malaria vaccine trials in semi-immune adults and pre-school children residing in a malaria endemic area. Results: Fixation, permeabilization, and staining of infected RBCs were adapted for best operation in flow cytometry. As asexual blood-stage vaccine candidates are designed to induce antibody patterns similar to those in semi-immune adults, serial dilutions of sera from heavily exposed individuals were compared to naïve controls to determine optimal antibody dilutions. To eliminate investigator effects introduced by manual gating, a non-biased algorithm (OSA) for data-driven gating was developed. OSA-derived results correlated well with those obtained by manual gating (r between 0.79 and 0.99) and outperformed other model-driven gating methods. Bland-Altman plots confirmed the agreement of manual gating and OSA-derived results. A 1.33-fold increase (p=0.003) in the number of positive cells after vaccination in a subgroup of pre-school children vaccinated with 100 μg GMZ2 was present and in vaccinated adults from the same region we measured a baseline-corrected 1.23-fold, vaccine-induced increase in mean fluorescence intensity of positive cells (p=0.03). Conclusions: The current workflow advances detection and quantification of anti-plasmodial antibodies through improvement of a bias-prone, low-throughput to an unbiased, semi-automated, scalable method. In conclusion, this work presents a novel method for immunofluorescence assays in malaria research. [ABSTRACT FROM AUTHOR]

Summary: Background: The RTS,S/AS01E candidate malaria vaccine is being developed for immunisation of infants in Africa through the expanded programme on immunisation (EPI). 8 month follow-up data have been reported for safety and immunogenicity of RTS,S/AS01E when integrated into the EPI. We report extended follow-up to 19 months, including efficacy results. Methods: We did a randomised, open-label, phase 2 trial of safety and efficacy of the RTS,S/AS01E candidate malaria vaccine given with EPI vaccines between April 30, 2007, and Oct 7, 2009, in Ghana, Tanzania, and Gabon. Eligible children were 6–10 weeks of age at first vaccination, without serious acute or chronic illness. All children received the EPI diphtheria, tetanus, pertussis (inactivated whole-cell), and hepatitis-B vaccines, Haemophilus influenzae type b vaccine, and oral polio vaccine at study months 0, 1, and 2, and measles vaccine and yellow fever vaccines at study month 7. Participants were randomly assigned (1:1:1) to receive three doses of RTS,S/AS01E at 6, 10, and 14 weeks (0, 1, 2 month schedule) or at 6 weeks, 10 weeks, and 9 months (0, 2, 7 month schedule) or placebo. Randomisation was according to a predefined block list with a computer-generated randomisation code. Detection of serious adverse events and malaria was by passive case detection. Antibodies against Plasmodium falciparum circumsporozoite protein and HBsAg were monitored for 19 months. This study is registered with ClinicalTrials.gov, number NCT00436007. Findings: 511 children were enrolled. Serious adverse events occurred in 57 participants in the RTS,S/AS01E 0, 1, 2 month group (34%, 95% CI 27–41), 47 in the 0, 1, 7 month group (28%, 21–35), and 49 (29%, 22–36) in the control group; none were judged to be related to study vaccination. At month 19, anticircumsporozoite immune responses were significantly higher in the RTS,S/AS01E groups than in the control group. Vaccine efficacy for the 0, 1, 2 month schedule (2 weeks after dose three to month 19, site-adjusted according-to-protocol analysis) was 53% (95% CI 26–70; p=0·0012) against first malaria episodes and 59% (36–74; p=0·0001) against all malaria episodes. For the entire study period, (total vaccinated cohort) vaccine efficacy against all malaria episodes was higher with the 0, 1, 2 month schedule (57%, 95% CI 33–73; p=0·0002) than with the 0, 1, 7 month schedule (32% CI 16–45; p=0·0003). 1 year after dose three, vaccine efficacy against first malaria episodes was similar for both schedules (0, 1, 2 month group, 61·6% [95% CI 35·6–77·1], p<0·001; 0, 1, 7 month group, 63·8% [40·4–78·0], p<0·001, according-to-protocol cohort). Interpretation: Vaccine efficacy was consistent with the target put forward by the WHO-sponsored malaria vaccine technology roadmap for a first-generation malaria vaccine. The 0, 1, 2 month vaccine schedule has been selected for phase 3 candidate vaccine assessment. Funding: Program for Appropriate Technology in Health Malaria Vaccine Initiative; GlaxoSmithKline Biologicals. [Copyright &y& Elsevier]

Background: Pandemic community-acquired methicillin-resistant Staphylococcus aureus isolates (CA-MRSA) predominantly encode the Panton-Valentine leukocidin (PVL), which can be associated with severe infections. Reports from non-indigenous Sub-Saharan African populations revealed a high prevalence of PVL-positive isolates. The objective of our study was to investigate the S. aureus carriage among a remote indigenous African population and to determine the molecular characteristics of the isolates, particularly those that were PVL-positive. Methodology/Principal Findings: Nasal S. aureus carriage and risk factors of colonization were systematically assessed in remote Gabonese Babongo Pygmies. Susceptibility to antibiotics, possession of toxin-encoding genes (i.e., PVL, enterotoxins, and exfoliative toxins), S. aureus protein A (spa) types and multi-locus sequence types (MLST) were determined for each isolate. The carriage rate was 33%. No MRSA was detected, 61.8% of the isolates were susceptible to penicillin. Genes encoding PVL (55.9%), enterotoxin B (20.6%), exfoliative toxin D (11.7%) and the epidermal cell differentiation inhibitor B (11.7%) were highly prevalent. Thirteen spa types were detected and were associated with 10 STs predominated by ST15, ST30, ST72, ST80, and ST88. Conclusions: The high prevalence of PVL-positive isolates among Babongo Pygmies demands our attention as PVL can be associated with necrotinzing infection and may increase the risk of severe infections in remote Pygmy populations. Many S. aureus isolates from Babongo Pygmies and pandemic CA-MRSA-clones have a common genetic background. Surveillance is needed to control the development of resistance to antibiotic drugs and to assess the impact of the high prevalence of PVL in indigenous populations. Author Summary: Staphylococcus aureus is a bacterium that colonizes humans worldwide. The anterior nares are its main ecological niche. Carriers of S. aureus are at a higher risk of developing invasive infections. Few reports indicated a different clonal structure and profile of virulence factors in S. aureus isolates from Sub-Saharan Africa. As there are no data about isolates from remote indigenous African populations, we conducted a cross-sectional survey of S. aureus nasal carriage in Gabonese Babongo Pygmies. The isolates were characterized regarding their susceptibility to antibiotic agents, possession of virulence factors and clonal lineage. While similar carriage rates were found in populations of industrialized countries, isolates that encode the genes for the Panton-Valentine leukocidin (PVL) were clearly more prevalent than in European countries. Of interest, many methicillin-susceptible S. aureus isolates from Babongo Pygmies showed the same genetic background as pandemic methicillin-resistant S. aureus (MRSA) clones. We advocate a surveillance of S. aureus in neglected African populations to control the development of resistance to antibiotic drugs with particular respect to MRSA and to assess the impact of the high prevalence of PVL-positive isolates. [ABSTRACT FROM AUTHOR]

Background: Pandemic community-acquired methicillin-resistant Staphylococcus aureus isolates (CA-MRSA) predominantly encode the Panton-Valentine leukocidin (PVL), which can be associated with severe infections. Reports from non-indigenous Sub-Saharan African populations revealed a high prevalence of PVL-positive isolates. The objective of our study was to investigate the S. aureus carriage among a remote indigenous African population and to determine the molecular characteristics of the isolates, particularly those that were PVL-positive. Methodology/Principal Findings: Nasal S. aureus carriage and risk factors of colonization were systematically assessed in remote Gabonese Babongo Pygmies. Susceptibility to antibiotics, possession of toxin-encoding genes (i.e., PVL, enterotoxins, and exfoliative toxins), S. aureus protein A (spa) types and multi-locus sequence types (MLST) were determined for each isolate. The carriage rate was 33%. No MRSA was detected, 61.8% of the isolates were susceptible to penicillin. Genes encoding PVL (55.9%), enterotoxin B (20.6%), exfoliative toxin D (11.7%) and the epidermal cell differentiation inhibitor B (11.7%) were highly prevalent. Thirteen spa types were detected and were associated with 10 STs predominated by ST15, ST30, ST72, ST80, and ST88. Conclusions: The high prevalence of PVL-positive isolates among Babongo Pygmies demands our attention as PVL can be associated with necrotinzing infection and may increase the risk of severe infections in remote Pygmy populations. Many S. aureus isolates from Babongo Pygmies and pandemic CA-MRSA-clones have a common genetic background. Surveillance is needed to control the development of resistance to antibiotic drugs and to assess the impact of the high prevalence of PVL in indigenous populations. [ABSTRACT FROM AUTHOR]

Background: Drug resistance contributes to the global malaria burden. Plasmodium falciparum dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) polymorphisms confer resistance to sulphadoxinepyrimethamine (SP). Methods: The study assessed the frequency of SP resistance-conferring polymorphisms in Plasmodium falciparumpositive samples from two clinical studies in Lambaréné. Their role on treatment responses and transmission potential was studied in an efficacy open-label clinical trial with a 28-day follow-up in 29 children under five with uncomplicated malaria. Results: SP was well tolerated by all subjects in vivo. Three subjects were excluded from per-protocol analysis. PCR-corrected, 12/26 (46%) achieved an adequate clinical and parasitological response, 13/26 (50%) were late parasitological failures, while 1/26 (4%) had an early treatment failure, resulting in early trial discontinuation. Of 106 isolates, 98 (92%) carried the triple mutant dhfr haplotype. Three point mutations were found in dhps in a variety of haplotypic configurations. The 437G + 540E double mutant allele was found for the first time in Gabon. Conclusions: There is a high prevalence of dhfr triple mutant with some dhps point mutations in Gabon, in line with treatment failures observed, and molecular markers of SP resistance should be closely monitored. [ABSTRACT FROM AUTHOR]

Background: The development and spread of drug resistant Plasmodium falciparum strains is a major concern and novel anti-malarial drugs are, therefore, needed. Ferroquine is a ferrocenic derivative of chloroquine with proven anti-malarial activity against chloroquine-resistant and -sensitive P. falciparum laboratory strains. Methods: Adult young male aged 18 to 45 years, asymptomatic carriers of P. falciparum, were included in twodose escalation, double-blind, randomized, placebo-controlled Phase I trials, a single dose study and a multiple dose study aiming to evaluate oral doses of ferroquine from 400 to 1,600 mg. Results: Overall, 54/66 patients (40 and 26 treated in the single and multiple dose studies, respectively) experienced at least one adverse event, 15 were under placebo. Adverse events were mainly gastrointestinal symptoms such as abdominal pain (16), diarrhoea (5), nausea (13), and vomiting (9), but also headache (11), and dizziness (5). A few patients had slightly elevated liver parameters (10/66) including two patients under placebo. Moderate changes in QTc and morphological changes in T waves were observed in the course of the study. However, no adverse cardiac effects with clinical relevance were observed. Conclusions: These phase I trials showed that clinically, ferroquine was generally well-tolerated up to 1,600 mg as single dose and up to 800 mg as repeated dose in asymptomatic young male with P. falciparum infection. Further clinical development of ferroquine, either alone or in combination with another anti-malarial, is highly warranted and currently underway. [ABSTRACT FROM AUTHOR]

Objectives To evaluate the epidemiologic data of parasitic infections and co-infections in pregnant women in Lambaréné, Gabon. Methods In Lambaréné, Gabon – a region of high endemicity for Plasmodium falciparum and helminths – we conducted a longitudinal survey of malaria and helminth infections during pregnancy. Results Of 388 pregnant women included in the study, 98 (25%) experienced at least one episode of P. falciparum infection (incidence of 2.6 infections per year of pregnancy). One hundred and seventy pregnant women (49%) were infected with intestinal helminths, and 41 (12%) harboured Shistosoma haematobium. In total, 230 (65%) pregnant women carried at least one parasitic infection are 74 (22%) harboured at least two or more parasite species. Ascaris lumbricoides and primiparity were independently associated with Plasmodium infection during pregnancy [odds ratio (95% confidence intervals) 2.4, (1.4–3.8); 2.1, (1.3–3.5), respectively]. Conclusion This study shows a high burden of parasitic infections with substantial degree of parasitic co-infections in pregnant women in a Central African region. This may have implications for immunological studies and operational research involving pregnant women. [ABSTRACT FROM AUTHOR]

Abstract: Malaria is still one of the major public health threats in sub-Saharan Africa. An effective vaccine could be a sustainable control measure that can be integrated into existing health infrastructures. The malaria vaccine candidate GMZ2 is a recombinant fusion protein of conserved parts of Plasmodium falciparum Glutamate Rich Protein and Merozoite Surface Protein 3 adjuvanted with aluminium hydroxide. GMZ2 is immunogenic and well tolerated in malaria-naive adults from Germany. To assess safety and immunogenicity in malaria-exposed individuals, 40 adults from Lambaréné, Gabon were randomly assigned to receive either 100μg GMZ2 or a rabies control vaccine three times in monthly intervals. Both vaccines were well tolerated. One month after a full course of vaccination, GMZ2-vaccinated individuals had 1.4-fold (95% confidence interval: [1.1, 1.7]) higher baseline-corrected anti-GMZ2 antibody levels and more GMZ2-specific memory B-cells compared to the rabies group (p =0.039), despite a high prevalence of GMZ2-specific immune reactivity due to previous intense exposure to P. falciparum. [ABSTRACT FROM AUTHOR]

Background. Molecular mechanisms involved in the pathogenesis of severe Plasmodium falciparum malaria—specifically, cerebral malaria—are still unclear. Transforming growth factor b (TGF-b) family members are important regulators of inflammation that influence malaria pathogenesis. The soluble form of the auxiliary receptor endoglin (sEng) may play a role in malaria pathogenesis. Methods. Serum levels of sEng were measured using enzyme-linked immunosorbent-assay in Gabonese children with cerebral malaria (n = 7), severe malaria (n = 43), or uncomplicated malaria (n = 43) and were compared with levels in healthy control subjects (n = 25) and in another infectious disease group (n = 8). Results. Serum sEng levels were higher in patients with cerebral malaria and all patients with severe malaria when compared with levels in patients in the other infection group and the healthy control group. Furthermore, sEng correlated significantly with disease severity. Only 7% of patients with uncomplicated malaria and none of the control patients (patients in the other infection group or the healthy control group) had serum levels higher than 12 ng/mL, whereas this was found in 85.7% of patients with cerebral malaria and 46.5% of patients with severe malaria. Conclusions. High sEng levels may attenuate anti-inflammatory response resulting in clinical deterioration of patients with P. falciparum malaria. Our results further corroborate the role of the vascular compartment, especially the endothelium, in severe malaria pathogenesis. [ABSTRACT FROM AUTHOR]

In the context of a trial studying intermittent preventive sulfadoxine- pyrimethamine treatment of malaria in infants in Lambaréné, Gabon, children aged 18-30 months were followed up after having received their last dose at an age of 15 months. In the intention-to-treat population, the protective efficacy against all malaria episodes was -18.0 (95% confidence interval, -97.4 to 29.5; P=.529). The protective efficacy against first or only anemia episode was -45.3 (95% confidence interval, -234.5 to 36.3; P=.375). The protective efficacies were negative and were not statistically significant. These results do not appear to support the concept of a rebound effect after intermittent preventive sulfadoxine-pyrimethamine treatment of malaria in infants. [ABSTRACT FROM AUTHOR]

The article focuses on a study which analysed the safety and efficacy of intermittent preventive treatment with sulfadoxine-pyrimethamine for malaria in African infants. The double-blind, randomized, placebo-controlled trials were conducted in African countries that include Tanzania, Mozambique, Gabon and Ghana. Main outcomes measured by the researchers include incidence of clinical malaria, risk of anemia and incidence of hospital admissions and adverse effects in infants up to 12 months of age. Interpretation of the research findings indicate the efficacy of the vaccine across a range of malaria transmission settings.

Background: The malaria vaccine candidate antigen RTS,S includes parts of the pre-erythrocytic stage circumsporozoite protein fused to the Hepatitis B surface antigen. Two Adjuvant Systems are in development for this vaccine, an oil-in water emulsion - based formulation (AS02) and a formulation based on liposomes (AS01). Methods & Principal Findings: In this Phase II, double-blind study (NCT00307021), 180 healthy Gabonese children aged 18 months to 4 years were randomized to receive either RTS,S/AS01E or RTS,S/AS02D, on a 0-1-2 month vaccination schedule. The children were followed-up daily for six days after each vaccination and monthly for 14 months. Blood samples were collected at 4 time-points. Both vaccines were well tolerated. Safety parameters were distributed similarly between the two groups. Both vaccines elicited a strong specific immune response after Doses 2 and 3 with a ratio of anti-CS GMT titers (AS02D/AS01E) of 0.88 (95% CI: 0.68-1.15) post-Dose 3. After Doses 2 and 3 of experimental vaccines, anti-CS and anti-HBs antibody GMTs were higher in children who had been previously vaccinated with at least one dose of hepatitis B vaccine compared to those not previously vaccinated. Conclusions: RTS,S/AS01E proved similarly as well tolerated and immunogenic as RTS,S/AS02D, completing an essential step in the age de-escalation process within the RTS,S clinical development plan. Trial Registration: ClinicalTrials.gov. NCT00307021 [ABSTRACT FROM AUTHOR]

Abstract: The aim of this paper is to explore attitudes of mothers towards childhood vaccinations and reasons for non-attendance and non-adherence to mother–child clinics (MCCs). Forty in-depth interviews with mothers of children under 5 years of age revealed positive attitudes towards vaccination that seem at odds with the region''s observed low vaccination coverage. Important reasons for MCC non-attendance included distance to the MCC, transport costs, negative experiences at MCCs (such as interactions with unfriendly staff) and mothers’ feeling of shame provoked by different, often poverty-associated reasons such as attending the clinic with a dirty or poorly clothed child. [Copyright &y& Elsevier]

Abstract: We recently showed that IL-21 is associated with high level of anti-EBA-175 IgG1 and IgG3. Here we have investigated the ability of two malarial antigens, Glutamate-rich protein and merozoite surface protein 3 to induce IL-21 production from PBMCs from malaria-exposed and non-exposed donors. We found that malaria-exposed donors produced significantly more IL-21 compared to non-exposed donors. These data suggest that IL-21 could be involved in the acquisition of immunity to malaria. [Copyright &y& Elsevier]

Background: Mannose binding lectin (MBL) has an important role in the activation of the complement system and opsonization of pathogenic microorganisms. Frequent polymorphisms found in the MBL2 gene affect the concentration and functionality of the protein and are associated with enhanced susceptibility to severe malaria in African children. Most MBL2 typing strategies were designed to the analysis of selected variants, the significance of whole haplotypes is poorly known. In this work, a new typing strategy was developed and validated in an association analysis of MBL2 with adult asymptomatic infection. Methods: MBL2 allele-specific fragments of 144 healthy Gabonese adults were amplified by using haplotypespecific sequencing (HSS), a new strategy that combines sequence-specific PCR and sequence-based typing. The Gabonese were investigated for the presence of Plasmodium falciparum parasitaemia by the amplification of parasite genes, immunochromatographic antigen detection and microscopic analysis. HSS results were also compared with a previously used real-time PCR (RT-PCR) method in 72 Euro-Brazilians. Results: Fourteen polymorphisms were identified beside the commonly investigated promoter (H, L; X, Y; P, Q) and exon 1 (A, O; O = B, C or D) variants. The MBL2*LYPA/LYPA genotype was associated with the absence of asymptomatic infection (P = 0.017), whereas the MBL2*LYQC haplotype and YA/YO + YO/YO genotypes were associated with positive parasite counts in asymptomatic adults (P = 0.033 and 0.018, respectively). The associations were specific to LYPA (identical to the reference sequence Y16577) and LYQC (Y16578) and would not have been revealed by standard genotyping, as there was no association with LYPA and LYQC haplotypes carrying new polymorphisms defined by sequence-based typing. In contrast, HSS and RT-PCR produced very similar results in the less diverse European-derived population. Conclusion: In this work, a new typing strategy for a highly polymorphic gene was developed and validated focusing on the asymptomatic status of P. falciparum-infected adults. In populations with high nucleotide diversity, it allowed for the identification of associations with fine-scaled haplotypes that would not have been found using common typing techniques. In this preliminary study, MBL2 haplotypes or SNPs linked to them were found associated with susceptibility to infection and parasitaemia control of asymptomatic adults. [ABSTRACT FROM AUTHOR]

Background. Plasmodium falciparum malaria is a common cause of morbidity in African children, but identifying those who are likely to die is problematic. Previous studies suggested that circulating malarial pigment might be a useful predictor of severity, but none were large enough to detect any association with mortality. Methods. We used thick blood smears performed on admission for 26,296 children hospitalized with P. falciparum at 1 of 6 hospitals in the Severe Malaria in African Children network to assess the prognostic value of pigmentcontaining granulocytes, monocytes, and parasites. Results. Although at all but one of the study sites the risk of mortality for subjects presenting with >5 pigmented granulocytes per 200 white blood cells was higher than in subjects with no pigmented granulocytes, adjusted odds ratios estimated through logistic regression, which included other established markers of severe malaria, suggested that associations between pigmented cells and mortality were moderate to nonexistent in most sites. The predictive ability of pigmented cells was low, as measured by the change in the area under the receiver operating characteristic curve of logistic regression models. Conclusions. Although high levels of pigmented cells were associated with a fatal outcome in some study sites, they were not useful predictors of outcome across Africa. [ABSTRACT FROM AUTHOR]

Background. Plasmodium falciparum infection during pregnancy is associated with stillbirth, fetal growth restriction, and low birth weight. An additional consequence may be increased risk of malaria in early life, although the epidemiological evidence of this consequence is limited. Methods. A cohort of 527 children were observed actively every month for 30 months after delivery. Offspring of mothers with microscopically detectable placental P. falciparum infection at the time of delivery were defined as exposed. The outcome measure was malaria (parasitemia and fever). Analyses were performed using Cox proportional hazard models and were stratified by gravidity. Results. Overall, offspring of mothers with placental P. falciparum infection had a significantly higher risk of clinical malaria during the first 30 months of life (adjusted hazard ratio, 2.1; 95% confidence interval [CI], 1.2-3.7). The adjusted hazard ratio for offspring of multigravidae was 2.6 (95% CI, 1.3-5.3), and that for primigravidae was 1.5 (95% CI, 0.6-3.8). The offspring of placenta-infected primigravidae had no episodes of malaria during the first year of life. Conclusions. Our findings show that active placental P. falciparum infection detected at delivery is associated with an ~2-fold greater risk of malaria during early life, compared with noninfection. The fact that persons born to infected multigravidae rather than primigravidae appear to be at greater risk emphasizes the importance of preventing malaria in mothers of all gravidities. [ABSTRACT FROM AUTHOR]

Background. The development of novel artemisinin-combination therapies suitable for the treatment of pediatric patients suffering from malaria is a research priority. The aim of this study was to investigate a novel fixed-dose pyronaridine-artesunate combination for the treatment of uncomplicated falciparum malaria in Gabonese patients 2-14 years old. Methods. The study was designed as an open-label dose-escalation study recruiting 60 pediatric patients sequentially in 4 treatment cohorts: study drugs were administered once daily for 3 days, as tablet coformulations (pyronaridine: artesunate ratios of 6:2, 9:3, and 12:4 mg/kg) and as a granule coformulation (pyronaridine:artesunate ratio of 9:3 mg/kg). The primary end points were tolerability, safety, and pharmacokinetics of pyronaridine-artesunate treatment. Efficacy was treated as a secondary outcome measure. Results. The drugs had a good tolerability and safety profile, at all dose levels. Pharmacokinetic analysis revealed a dose-dependent increase in the maximum plasma/blood concentration and the area under the curve, as well as comparable relative bioavailability for the granule coformulation. Polymerase chain reaction- corrected cure rates at day 28 were 100% in per-protocol analysis, at all dose levels. Conclusions. Pyronaridine-artesunate is a promising novel artemisinin-combination therapy for pediatric patients with uncomplicated Plasmodium falciparum malaria, and the development of both the tablet and the granule coformulations is warranted. Trial Registration. Clinical Trials.gov identifier NCT00331136. [ABSTRACT FROM AUTHOR]

Background. Pregnancy-associated malaria is known to modify fetal immunity. Most previous studies have been cross-sectional in nature and have focused on the priming of acquired immune responses in utero. In this context, the influence of the timing and/or duration of placental infection with Plasmodium falciparum are unknown, and changes to innate immune responses have not been studied extensively. Methods. Pregnant women in Gabon, where P. falciparum infection is endemic, were followed up through monthly clinical and parasitological examinations from the second trimester to delivery. Cells of neonates born to mothers who had acquired P. falciparum infection ⩽1 month before delivery had significantly altered interferon-γ and tumor necrosis factor-α responses after stimulation with the Toll-like receptor (TLR) ligands lipopolysaccharide and polyinosine-polycytidylic acid, compared with cells of neonates born either to mothers free of P. falciparum infection or to mothers who were successfully treated for malaria during pregnancy. An independent association between parity and neonatal TLR responsiveness was also discerned in our study. Conclusion. P. falciparum infection history during pregnancy appears to have a pronounced effect on neonatal innate immune responses. The observed effects may have profound implications for the outcome of newly encountered infections in early life. [ABSTRACT FROM AUTHOR]

Background. Molecular mechanisms involved in the pathogenesis of severe malaria caused by Plasmodium falciparum are not fully understood. Matrix metalloproteinases (MMPs) are enzymes that proteolytically degrade both the extracellular matrix and nonmatrix substances with various functions in the modulation of immune response. The key inhibitors of MMPs are the tissue inhibitors of metalloproteinases (TIMPs). Methods. We studied levels of MMP-8, MMP-9, TIMP-1, and TIMP-2 on admission and after 24 h, using an enzyme-linked immunosorbent assay, in serum specimens from 50 Gabonese children with severe malaria, 43 children with uncomplicated malaria, and 27 healthy control children. Results. Serum MMP-8 and TIMP-1 levels were significantly higher in the severe malaria and uncomplicated malaria groups, compared with those in the control group (P < .001). TIMP-1 levels were significantly higher in patients with severe malaria, compared with those in patients with uncomplicated malaria (P < .001). High TIMP-1 levels were significantly correlated with malaria severity, as determined by the simplified multiorgan dysfunction score (Spearman rank-correlation coefficient, 0.55; P < .001). Conclusions. TIMP-1 is associated with signs and symptoms of severe malaria. MMP-8 levels are elevated in patients with severe or uncomplicated P. palciparum malaria. MMPs and TIMPs may be relevant in the pathogenesis of severe malaria, either as proteolytic enzymes that degrade the extracellular matrix or as effectors and regulators of the immune response. [ABSTRACT FROM AUTHOR]

Background: Antipyretic drugs are widely used in children with fever, though there is a controversy about the benefit of reducing fever in children with malaria. In order to assess the effect of ibuprofen on fever compared to placebo in children with uncomplicated Plasmodium falciparum malaria in Gabon, a randomized double blind placebo controlled trial, was designed. Methods: Fifty children between two and seven years of age with uncomplicated malaria were included in the study. For the treatment of fever, all patients "received" mechanical treatment when the temperature rose above 37.5°C. In addition to the mechanical treatment, continuous fanning and cooling blanket, patients were assigned randomly to receive ibuprofen (7 mg/kg body weight, every eight hours) or placebo. Results: The fever clearance time using a fever threshold of 37.5°C was similar in children receiving ibuprofen compared to those receiving placebo. The difference was also not statistically significant using a fever threshold of 37.8°C or 38.0°C. However, the fever time and the area under the fever curve were significantly smaller in the ibuprofen group compared to the placebo group. Conclusion: Ibuprofen is effective in reducing the time with fever. The effect on fever clearance is less obvious and depends on definition of the fever threshold. [ABSTRACT FROM AUTHOR]

Background: Insecticide-treated bed nets (ITNs) range among the most effective measures of malaria prophylaxis, yet their implementation level in sub-Saharan Africa is still low. The goal of this study was to investigate the influence of socio-economic factors on the use of bed nets by mothers in Gabon. Methods: A cross-sectional study was conducted completing pre-tested, interviewer-administered questionnaires exploring socioeconomic proxy measures with 397 mothers or guardians of young children. Respondents were grouped according to their socio-economic situation, using scores. The condition of the bed nets was evaluated during a home visit. Results: Socio-economic factors of wellbeing were negatively associated with bed net use, such as living in a stone house (OR 0.26, 95% CI 0.14-0.48), running water in the house (OR 0.44, 95% CI 0.21-0.92), shower/flush toilet in the house (OR 0.39/0.34, 95% CI 0.21-0.75/0.16-0.73), ownership of a freezer (OR 0.50, 95% CI 0.26-0.96) and belonging to the highest group in the economic score (OR 0.32, 95% CI 0.15-0.67). In contrast, similar factors were positively associated with a good maintenance condition of the bed nets: higher monthly income (OR 5.64, 95% CI 2.41-13.19) and belonging to the highest group in the economic score (OR 2.55, 95% CI 1.19 - 5.45). Conclusion: Among the poorest families in Lambaréné the coverage with untreated nets (UTNs) is the highest, but the condition of these UTNs is the worst. To achieve a broad implementation of ITNs in Lambaréné, there is an urgent need for educational programmes as well as need-tailored marketing strategies for ITNs. [ABSTRACT FROM AUTHOR]

Abstract: Clindamycin is safe and effective for the treatment of Plasmodium falciparum malaria, but its use as monotherapy is limited by unacceptably slow initial clinical response rates. To investigate whether the protracted action is due to an accumulative, time of exposure-dependent or a delayed effect on parasite growth, we studied the in vivo and in vitro pharmacodynamic profiles of clindamycin against P. falciparum. In vivo, elimination of young, circulating asexual parasite stages during treatment with clindamycin displayed an unusual biphasic kinetic: a plateau phase was followed by a precipitated decline of asexual parasite densities to nearly undetectable levels after 72 and 60h in adult patients and asymptomatic children, respectively, suggesting an uninhibited capacity to establish a second, but not third, infectious cycle. In vitro, continuous exposure of a laboratory-adapted P. falciparum strain to clindamycin with concentrations of up to 100μM for two replication cycles (96h) did not produce inhibitory effects of >50% compared with drug-free controls as measured by the production of P. falciparum histidine-rich protein II (PfHRP2). PfHRP2 production was completely arrested after the second cycle (96–144h) (>10,000-fold decrease of mean half-inhibitory concentrations measured at 96–144h compared to 48–96h). Furthermore, incubation with clindamycin during only the first (0–48h) versus three (0–144h) parasite replication cycles led to comparable inhibition of PfHRP2 production in the third infectious cycle (96–144h) (mean IC99 of 27 and 22nM, respectively; P =0.2). When parasite cultures were exposed to different concentrations of clindamycin ranging from 50 to 1,000nM for 72h and followed up in an experiment designed to simulate a typical 3-day treatment regimen, parasitaemia was initially suppressed below the microscopic detection threshold. Nonetheless, parasites reappeared in a dose-dependent manner after removal of drug at 72h but not in continuously drug-exposed controls. The delayed, but potent, antimalarial effect of clindamycin appears to be of greatest potential benefit in new combinations of clindamycin with rapidly acting antimalarial combination partners. [Copyright &y& Elsevier]

Background. To extend our previous findings showing an imbalanced distribution of immunoglobulin G2 (IgG2) antibodies to Plasmodium falciparum merozoite surface protein 2 (MSP2) and a higher frequency of infection with multiple P. falciparum strains in Gabonese children with sickle cell trait (hemoglobin AS), human Fcγ receptor (FcγR) IIa (CD32) polymorphism and the rate of in vitro invasion of red blood cells (RBCs) from subjects with either hemoglobin AA or AS by multiple P. falciparum strains were investigated. Methods. FcγRIIa mutation at amino acid position 131 (arginine or histidine) was detected by polymerase chain reaction, and in vitro cultures for parasites were used to assess the invasion rate. Results. FcγRIIa polymorphism is normally distributed in this population, with no preferential carriage by children with hemoglobin AS. Lower levels of IgG2 subclass antibodies to MSP2 peptides were independently associated with the FcγRIIa-R131 allele and with carriage of hemoglobin AS. Our data suggest that IgG3 antibody responses to MSP2 epitopes could be exacerbated by lower IgG2 levels in children with hemoglobin AS. Conclusions. The higher rate of invasion of RBCs in the presence of multiple strains may indicate that several invasion pathways are solicited simultaneously, and the longer persistence of ring forms in RBCs from the subjects with hemoglobin AS might reflect a slower multiplication phase, leading to a longer circulation and enhanced phagocytosis of these nonpathogenic parasite forms. This may contribute to the protection against P. falciparum malaria observed in children with hemoglobin AS. [ABSTRACT FROM AUTHOR]

Abstract: We determined the incidence of both malaria and asymptomatic parasitaemia in infants under the age of 3 months within the framework of a longitudinal cohort study in Lambaréné, Gabon, between December 2002 and July 2004. Of 878 infants who were included at birth, we identified malaria in three infants and, additionally, asymptomatic parasitaemia in six infants. The malaria incidence density was 1.1/1000 person-months or 0.1% of observations. Our findings underpin the notion that the incidence of malaria and parasitaemia in infants below the age of 3 months is very low. [Copyright &y& Elsevier]