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Genetic diversity of surface exposed and stage specific Plasmodium falciparum immunogenic proteins pose a major roadblock to developing an effective malaria vaccine with broad and long-lasting immunity. We conducted a prospective genetic analysis of candidate antigens (msp1, ama1, rh5, eba175, glurp, celtos, csp, lsa3, Pfsea, trap, conserved chrom3, hyp9, hyp10, phistb, surfin8.2, and surfin14.1) for malaria vaccine development on 2375 P. falciparum sequences from 16 African countries. We described signatures of balancing selection inferred from positive values of Tajima’s D for all antigens across all populations except for glurp. This could be as a result of immune selection on these antigens as positive Tajima’s D values mapped to regions with putative immune epitopes. A less diverse phistb antigen was characterised with a transmembrane domain, glycophosphatidyl anchors between the N and C- terminals, and surface epitopes that could be targets of immune recognition. This study demonstrates the value of population genetic and immunoinformatic analysis for identifying and characterising new putative vaccine candidates towards improving strain transcending immunity, and vaccine efficacy across all endemic populations.

The objective of this study was to analyze the effect of hydroxychloroquine or chloroquine associated with azithromycin on the QTc interval in Gabonese patients treated for COVID-19. Methods: This was an observational study conducted from April to June 2020, at the Libreville University Hospital Center in Gabon. Patients admitted for COVID-19 and treated with hydroxychloroquine or chloroquine, each combined with azithromycin were included. The QTc interval was measured upon admission and 48 h after starting treatment. The primary endpoint was QTc prolongation exceeding 60 ms and/or a QTc value exceeding 500 ms at 48 h. Results: Data from 224 patients, 102 (45.5%) who received hydroxychloroquine and 122 treated with chloroquine, were analyzed. The median baseline QTc was 396 (369–419) ms. After 48 h of treatment, 50 (22.3%) patients had a significant prolongation of QTc. This tended to be more frequent in patients treated with chloroquine (n = 33; 27.0%) than in those treated with hydroxychloroquine (n = 17; 16.7%) (p = 0.06). QTc prolongation exceeding 60 ms was found in 48 (21.3%) patients, while 11 patients had a (4.9%) QTc exceeding 60 ms at admission and exceeding 500 ms after 48 h. Conclusion: Early QTc prolongation is frequent in COVID-19 patients treated with hydroxychloroquine or chloroquine in association with azithromycin.

Background This cross-sectional study was carried out in different settlements of Gabon to determine the influence of single or multiple parasite carriage on haemoglobin (Hb) levels. Methods Between April 2015 and June 2016, healthy volunteers from urban, peri-urban and rural areas were screened for malaria, blood filariasis and intestinal parasitic infections using microscopic methods. Hb concentration was measured with a Hemocue analyser. The association between parasite carriage and anaemia was assessed. Results Among the 775 volunteers examined, 319 (41.2%) were from rural villages and 76.0% were adults. Filariasis, intestinal parasitic infections, Plasmodium falciparum and polyparasitism were detected in 15.6, 14.6, 9.5 and 6.8% of participants, respectively. Anaemia prevalence was 72.6%, with rates of mild, moderate and severe anaemia being 30.9, 61.1 and 8.0%, respectively. The median Hb level was lowest in the presence of hookworms (7.1 g/dl [interquartile range {IQR} 6.8–7.5]), Schistosoma intercalatum (6.9 g/dl), Trichuris trichiura (10.1 g/dl [IQR 8.9–11.5]) and Plasmodium falciparum (10.0 g/dl [IQR 9.1–11.2]) compared with filariaemia (12.1 g/dl [IQR 10.5–13.2]) (p=0.03). Moderate to severe anaemia predominated among those single-infected with P. falciparum (69.5%) or co-infected with intestinal parasitic infections and P. falciparum (76.2%), while it was found in only 23.2% of individuals with filariasis. All participants with soil-transmitted helminths and more than half with a Blastocystis sp. (68.8%) infection had moderate anaemia. Conclusions The prevalence of anaemia is high. Asymptomatic parasite carriage is associated with anaemia in this surveyed population in Gabon.

Filarial infections caused by Loa loa and Mansonella perstans are a considerable public health burden in rural regions of Central Africa. Rapid diagnostic tools for the detection of microfilariae in the blood are needed. Field’s stain is a rapid staining technique for microscopic slides originally established for malaria diagnostics. It requires less than 1 minute of staining compared with conventional staining protocols requiring at least 15 to 20 minutes for staining and could thus significantly accelerate diagnostics for human filariasis. Here we evaluated Field’s stain as a rapid staining technique in comparison to Giemsa stain for the detection of microfilariae in peripheral blood. Blood smears were collected from 175 participants residing in the region of Lambaréné and Fougamou, Gabon. Each participant’s samples were stained in parallel with Field’s stain and conventional Giemsa stain. Slides were then microscopically assessed and compared for qualitative and quantitative results by a blinded assessor for the two endemic filarial blood pathogens M. perstans and L. loa. Field’s stain shows excellent diagnostic performance characteristics for L. loa microfilariae compared with Giemsa staining. Concordance was favorable for M. perstans although lower than for L. loa. Field’s stain offers a rapid alternative to Giemsa stain for detection of L. loa microfilariae in thick blood smears. This could help accelerate diagnostics of blood filarial pathogens in mass screening programs or resource constrained health care institutions with high patient load.

Background: To perform molecular epidemiologic studies based on large cohorts, material such as RDTs or filter papers are useful for biological sample collection and extraction of RNA or DNA of good quality. Thus, we aimed to assess the quality of DNA extracted from malaria rapid diagnostic tests (RDTs) stored at various temperatures for the analysis of Plasmodium falciparum genetic diversity. Methods: Febrile patients benefitted from free malaria diagnosis using microscopy in a malaria sentinel site, at the Regional Hospital Estuaire-Melen, in Gabon, in 2015. P. falciparum isolates were collected onto one filter paper and 2 similar RDTs devices (Acon®) per patient. Nucleic acids were extracted with QiAmp Qiagen kit from paper and RDTs and the quality of the DNA was analyzed by msp1 gene amplification. Results: Msp1gene amplification was achieved in nucleic acids extracted from all filter papers and RDTs devices (n = 45, 100%). K1 alleles were detected in 93.3% (n = 42/45) of the samples and Mad20 alleles in 73.3% (n = 33/45). The number and the intensity of K1 and/or Mad20 fragments were comparable according to the sample collection material and the storage conditions (room temperature vs -20°C) of the samples. The size of the fragments indicating allelic diversity was comparable in 80% (n=36) of the samples. Conclusion: These data show that RDTs are a valuable source of DNA for malaria parasite genetic polymorphism analysis. Storage conditions of the devices did not influence the quality of DNA extracted from RDTs device, although some alleles may be missed.

Purpose Artesunate–amodiaquine (AS–AQ) and artemether–lumefantrine (AL) have been widely used for the treatment of uncomplicated Plasmodium falciparum malaria since 2005 in Gabon. Since 2011, a rebound of malaria morbidity has been observed in this country, while no survey evaluating ACT efficacy was performed. During the same period, parasite resistance against artemisinin has been reported in Asia. The aim of this study was to assess the efficacy and tolerability of these two drugs in two sentinel sites of Gabon 10 years after their implementation. Methods Children aged from 12 to 144 months with uncomplicated malaria were recruited at the Regional Hospital of Melen, Libreville and in the Urban Health Center of Franceville between March 2014 and September 2015. The therapeutic efficacy was evaluated according to the WHO 2008 protocol of 28-day follow-up and PCR-uncorrected/corrected treatment outcomes were assessed. Results One hundred and eighty-five children (98 ASAQ and 89 AL) were followed up until day 28. The PCR-corrected ACPR was 98.9% for AS–AQ and 96.4% for AL. Late therapeutic failure rate was 3.6% and 1.1% for AL and AS–AQ, respectively (p = 0.2). Adverse events and serious adverse events were rarely observed with both treatments. Conclusion AS–AQ and AL are still efficacious and well-tolerated for the treatment of uncomplicated malaria in Gabonese children.

Background For uncomplicated Plasmodium falciparum malaria, highly efficacious single-dose treatments are expected to increase compliance and improve treatment outcomes, and thereby may slow the development of resistance. The efficacy and safety of a single-dose combination of artefenomel (800 mg) plus ferroquine (400/600/900/1200 mg doses) for the treatment of uncomplicated P. falciparum malaria were evaluated in Africa (focusing on children ≤ 5 years) and Asia. Methods The study was a randomized, double-blind, single-dose, multi-arm clinical trial in patients aged > 6 months to kelch-13 mutations were explored. Results A total of 373 patients were treated: 289 African patients ≤ 5 years (77.5%), 64 African patients > 5 years and 20 Asian patients. None of the treatment arms met the target efficacy criterion for PCR-adjusted ACPR at Day 28 (lower limit of 95% confidence interval [CI] > 90%). PCR-adjusted ACPR at Day 28 [95% CI] in the PP Set ranged from 78.4% [64.7; 88.7%] to 91.7% [81.6; 97.2%] for the 400 mg to 1200 mg ferroquine dose. Efficacy rates were low in Vietnamese patients, ranging from 20 to 40%. A clear relationship was found between drug exposure (artefenomel and ferroquine concentrations at Day 7) and efficacy (primary endpoint), with higher concentrations of both drugs resulting in higher efficacy. Six distinct kelch-13 mutations were detected in parasite isolates from 10/272 African patients (with 2 mutations known to be associated with artemisinin resistance) and 18/20 Asian patients (all C580Y mutation). Vomiting within 6 h of initial artefenomel administration was common (24.6%) and associated with lower drug exposures. Conclusion The efficacy of artefenomel/ferroquine combination was suboptimal in African children aged ≤ 5 years, the population of interest, and vomiting most likely had a negative impact on efficacy. Trial registration ClinicalTrials.gov, NCT02497612. Registered 14 Jul 2015, https://clinicaltrials.gov/ct2/show/NCT02497612?term=NCT02497612&draw=2&rank=1

Background Malaria, filariasis, and intestinal parasitic infections (IPIs) are common and frequently overlap in developing countries. The prevalence and predictors of these infections were investigated in three different settlements (rural, semi-urban, and urban) of Gabon. Methods During cross-sectional surveys performed from September 2013 to June 2014, 451 individuals were interviewed. In addition, blood and stool samples were analysed for the presence of Plasmodium, filarial roundworm, intestinal protozoan, and helminth infections. Results Intestinal parasitic infections (61.1%), including intestinal protozoa (56.7%) and soil-transmitted helminths (STHs) (22.2%), predominated, whereas Plasmodium falciparum (18.8%), Loa loa (4.7%), and Mansonella perstans (1.1%) were less prevalent. Filariasis and STHs were mainly found in rural settlements, whereas a higher plasmodial infection prevalence rate was observed in the periurban area. The most common IPI was blastocystosis (48.6%), followed by ascaridiasis (13.7%), trichuriasis (11.8%), amoebiasis (9.3%), giardiasis (4.8%), and strongyloidiasis (3.7%). Hookworm was detected in one adult from rural Dienga. Adults had a higher prevalence of Blastocystis hominis and STHs, whereas Giardia duodenalis was more frequently observed among children aged below 5 years (P

Purpose Artesunate–amodiaquine (AS–AQ) and artemether–lumefantrine (AL) have been widely used for the treatment of uncomplicated Plasmodium falciparum malaria since 2005 in Gabon. Since 2011, a rebound of malaria morbidity has been observed in this country, while no survey evaluating ACT efficacy was performed. During the same period, parasite resistance against artemisinin has been reported in Asia. The aim of this study was to assess the efficacy and tolerability of these two drugs in two sentinel sites of Gabon 10 years after their implementation. Methods Children aged from 12 to 144 months with uncomplicated malaria were recruited at the Regional Hospital of Melen, Libreville and in the Urban Health Center of Franceville between March 2014 and September 2015. The therapeutic efficacy was evaluated according to the WHO 2008 protocol of 28-day follow-up and PCR-uncorrected/corrected treatment outcomes were assessed. Results One hundred and eighty-five children (98 ASAQ and 89 AL) were followed up until day 28. The PCR-corrected ACPR was 98.9% for AS–AQ and 96.4% for AL. Late therapeutic failure rate was 3.6% and 1.1% for AL and AS–AQ, respectively (p = 0.2). Adverse events and serious adverse events were rarely observed with both treatments. Conclusion AS–AQ and AL are still efficacious and well-tolerated for the treatment of uncomplicated malaria in Gabonese children.

Ebb and flow of parasite populations The population genetics of the malaria parasite Plasmodium falciparum across Africa is poorly understood but important to know for grasping the risks and dynamics of the spread of drug resistance. Harnessing the power of genomics, Amambua-Ngwa et al. of the Plasmodium Diversity Network Africa found substantial population structure within Africa that is consistent with human and vector population divergence (see the Perspective by Sibley). Specific signatures of selection by antimalarial drugs were detected, along with indications of the effect of colonization and slavery. Furthermore, whole-genome sequencing showed that there is extensive gene flow among the different regions and that Ethiopia has a distinctive population of P. falciparum , which may be indicative of coexistence with another malaria parasite, P. vivax. Science , this issue p. 813 ; see also p. 752

In order to follow the Preventive Chemotherapy for the transmission control as recommended by WHO, Gabon initiated in 2014 the mapping of Schistosomiasis and Soil Transmitted Helminthiasis (STH). Here we report the results of the Northern and Eastern health regions, representing a third of the land area and 12% of its total population. All the 9 departments of the two regions were surveyed and from each, 5 schools were examined with 50 schoolchildren per school. The parasitological examinations were realized using the filtration method for urine and the Kato-Katz technique for stool samples. Overall 2245 schoolchildren (1116 girls and 1129 boys), mean aged 11.28 ± 0.04 years, were examined. Combined schistosomiasis and STH affected 1270 (56.6%) with variation between regions, departments and schools. For schistosomiasis, prevalence were 1.7% across the two regions, with no significant difference (p>0.05) between the Northern (1.5%) and the Eastern (1.9%). Schistosomiasis is mainly caused by Schistosoma haematobium with a prevalence of 1.5%, 1.9% and 1.7%, respectively in the North, East and globally. STH are more common than schistosomiasis, with an overall prevalence of 56.1% significantly different between the Northern (58.1%) and Eastern (53.6%) regions (p = 0.034). Trichuris trichiura is the most abundant infection with a prevalence of 43.7% followed by Ascaris lumbricoides 35.6% and hookworms 1.4%. According to these results, an appropriate mass drug administration strategy is given for the control of each neglected tropical disease group surveyed.

Cystic echinococcosis (CE) is a globally endemic zoonosis caused by the larval stage of the Echinococcus granulosus sensu lato (s.l.) complex. Although the disease is known to be highly prevalent in certain parts of North and East Africa, data on CE, both in humans and definitive hosts, are extremely scarce for Central Africa. The present study assessed the epidemiology of CE in humans and dogs in rural Gabon. An ultrasound and serologic survey was conducted in volunteers from rural villages in Gabon. A two-step approach was used for serological testing with an indirect hemagglutination assay as a screening test and Western Blot as a confirmatory test. Fecal dog samples were analyzed microscopically, and polymerase chain reaction (PCR) amplification of nad1 and cox1 genes was performed when taeniid eggs were visible. Regional hospitals and the national reference center for parasitology in Gabon were contacted for information about previous cases of CE. Randomly selected communities were invited to participate. Three hundred and forty-eight human volunteers from these communities were screened. No suspected cases of CE were detected. Definitive host screening was performed from 128 fecal samples from representative subregions, but no eggs from E. granulosus s.l. were found. No documented cases of echinococcosis were reported from the local health-care institutions and the national diagnostic reference center in Gabon. Cystic echinococcosis seems to be very rare or absent in Gabon. The reason for this lack of evidence for echinococcosis is unknown, but the absence of livestock may play a major role.

Summary Background Artemisinin-based combination therapies (ACTs) are the recommended first-line treatment for uncomplicated Plasmodium falciparum malaria. Ferroquine is a new combination partner for fast-acting ACTs such as artesunate. We aimed to assess different doses of ferroquine in combination with artesunate against uncomplicated P falciparum malaria in a heterogeneous population in Africa. Methods We did a phase 2, multicentre, parallel-group, double-blind, randomised, dose-ranging non-inferiority trial at eight African hospitals (two in Gabon, three in Burkina Faso, one in Benin, and two in Kenya). We recruited patients presenting with acute P falciparum monoinfection (1000–200 000 parasites per μL), and a central body temperature of at least 37·5°C or history of fever in the past 24 h. We assessed patients in two sequential cohorts: cohort 1 contained adults (bodyweight >50 kg) and adolescents (aged ≥14 years, >30 kg), and cohort 2 contained children (aged 2–13 years, 15–30 kg). We randomly assigned patients (1:1:1:1) to receive artesunate 4 mg/kg per day plus ferroquine 2 mg/kg, 4 mg/kg, or 6 mg/kg, given double-blind once per day for 3 days, or ferroquine monotherapy 4 mg/kg per day given single-blind (ie, allocation was only masked from the patient) once per day for 3 days. We did 14 patient visits (screening, 3 treatment days and 48 h post-treatment surveillance, a visit on day 7, then one follow-up visit per week until day 63). The primary endpoint was non-inferiority of treatment in terms of PCR-corrected cure rate against a reference value of 90%, with a 10% non-inferiority margin, assessed in patients treated without major protocol deviations for parasitologically confirmed malaria. We assessed safety in all treated patients. This study is registered with ClinicalTrials.gov, number NCT00988507, and is closed. Findings Between Oct 16, 2009, and Sept 22, 2010, we randomly assigned 326 eligible patients to treatment groups, with last follow-up visit on Dec 1, 2010. 284 patients (87%) were available for per-protocol analyses. At day 28, PCR-confirmed cure was noted in 68 (97%, 95% CI 90–100) of 70 patients treated with ferroquine 2 mg/kg plus artesunate, 73 (99%, 93–100) of 74 with ferroquine 4 mg/kg plus artesunate, 71 (99%, 93–100) of 72 with ferroquine 6 mg/kg plus artesunate, and 54 (79%, 68–88) of 68 with ferroquine 4 mg/kg monotherapy. The three dose groups of ferroquine plus artesunate met the non-inferiority hypothesis. The most common adverse events were headache in cohort 1 (30 [19%] of 162 patients) and worsening malaria in cohort 2 (23 [14%] of 164 patients); occurrences were similar between treatment groups. Interpretation Ferroquine combined with artesunate was associated with high cure rates and was safe at all doses tested, and could be a promising new drug combination for the treatment of P falciparum malaria. Ferroquine could also partner other drugs to establish a new generation of antimalarial combinations, especially in regions that have developed resistance to ACTs. Funding Sanofi.

The present study determined and compared the genetic diversity of Plasmodium falciparum strains infecting children living in 2 areas from Gabon with different malaria endemicity. Blood samples were collected from febrile children from 2008 to 2009 in 2 health centres from rural (Oyem) and urban (Owendo) areas. Genetic diversity was determined in P. falciparum isolates by analyzing the merozoite surface protein-1 (msp1) gene polymorphism using nested-PCR. Overall, 168 children with mild falciparum malaria were included. K1, Ro33, and Mad20 alleles were found in 110 (65.5%), 94 (55.9%), and 35 (20.8%) isolates, respectively, without difference according to the site (P>0.05). Allelic families’ frequencies were comparable between children less than 5 years old from the 2 sites; while among the older children the proportions of Ro33 and Mad20 alleles were 1.7 to 2.0 fold higher at Oyem. Thirty-three different alleles were detected, 16 (48.5%) were common to both sites, and 10 out of the 17 specific alleles were found at Oyem. Furthermore, multiple infection carriers were frequent at Oyem (57.7% vs 42.2% at Owendo; P=0.04) where the complexity of infection was of 1.88 (±0.95) higher compared to that found at Owendo (1.55±0.75). Extended genetic diversity of P. falciparum strains infecting Gabonese symptomatic children and high multiplicity of infections were observed in rural area. Alleles common to the 2 sites were frequent; the site-specific alleles predominated in the rural area. Such distribution of the alleles should be taken into accounts when designing MSP1 or MSP2 malaria vaccine.

Giardiasis and cryptosporidiosis are now recognized as neglected tropical parasitic diseases. The risk of their dissemination in developing countries, such as Gabon, is increasing, due to urban crowding and poor sanitation. Accurate, simple and rapid diagnosis tools are thus necessary for the estimation of their real burden. The aim of this study was to evaluate the performances of the ImmunocardSTAT®Crypto/Giardia Rapid Assay test for the detection of Cryptosporidium (C.) spp. and Giardia (G.) duodenalis in children living in Libreville, Gabon. Stool samples of 173 healthy children were screened by routine microscopic using the merthiolate iodine formol concentration technique for Giardia, the modified Ziehl Neelsen (ZN) staining for Cryptosporidium and the ImmunocardSTAT® Crypto/Giardia RDT for the detection of Giardia and Cryptosporidium parasite forms and antigens respectively. G. duodenalis was detected with microscopy and the ImmunocardSTAT® Crypto/Giardia in 27 (15.6 %) and 22 (13.3 %) fecal samples respectively. C. spp. oocysts were found in 18 (10.4 %) ones, whereas only one sample was positive with the immunochromatographic assay. When microscopic examination was considered as the reference method, sensitivity and specificity of the ImmunocardSTAT® Crypto/Giardia Rapid Assay were found to be 63.0 %, 96.6 and 5.5 %, 99.3 % for G. duodenalis and C. spp. respectively. The prevalence of G. duodenalis and C. spp. carriage is high in children from Libreville. A low sensitivity of the ImmunocardSTAT® Crypto/Giardia for the detection of both parasites is observed. It is thus inappropriate as a diagnostic tool for detecting asymptomatic carriers.

Plasmodium population dynamics analysis may help to assess the impact of malaria control strategies deployment. In Gabon, new strategies have been introduced, but malaria is still a public health problem marked by a rebound of the prevalence in 2011. The aim of the study was to investigate the spatial and temporal distribution of P. falciparum strains in different areas in Gabon during a period of malaria transmission transition, between 2008 and 2011. A total of 109P. falciparum isolates were genotyped using nested-PCR of Pfmsp1 and Pfmsp2 genes. 3D7, FC27 and K1 allele frequencies were comparable between sites (p=0.9); those of Ro33 (93.6%; 44/47) and Mad20 (60%; 12/20) were significantly higher in isolates from Oyem (p0.01) and Port-Gentil (p=0.02), respectively. The frequency of multiples infections (77%) and the complexity of infection (2.66±1.44) were the highest at Oyem. Pfmsp1 gene analysis highlighted a trend of a decreasing frequency of K1 family, in Libreville and Oyem between 2008 and 2011; while that of Ro33 (p0.01) and Mad20 (p0.01) increased. The prevalence of multiple infections was comparable between both periods in each site: 42.2% vs 47.6% (p=0.6) in Libreville and 57.7% vs 61.7% in Oyem (p=0.8). In contrast, in 2011, the COI tends to be higher in Libreville and did not vary in Oyem. These data confirm an extended genetic diversity of P. falciparum isolates over time and according to geographic location in Gabon. Nevertheless, the impact of the deployment of malaria control strategies on the parasites genetic profile is not clearly established here.

Changes of lipid parameter concentrations are observed in patients suffering from malaria. However, there are few data on their evolution during the course of the infection and their relationship with the infection parameters. The levels of triglycerides (TG) and total cholesterol (TC) were measured during and after uncomplicated Plasmodium falciparum malaria in 122 children. The relationship with the antimalarial drug treatment, the parasite density and haemoglobin levels was also assessed. Mean TG levels were high before the treatment (1.9 ± 1.2 mmol/L) and at day 3 post-treatment (2.3 ± 1.3 mmol/L), then subsequently decreased to reach normal level from day 7. A negative correlation was found between haemoglobin (Hb) levels and TG (rho = -0.47; p < 0.01); previous high parasitaemia at inclusion was associated with a subsequent increase of TG levels after treatment administration. The majority of patients with hypertriglyceridemia were anaemic at day 3 (n = 20/20) and at day 7 (n = 18/19). Only 5 (4.1%) patients had hypertriglyceridemia at day 28. A trend toward a negative correlation between TC levels and parasite density was observed (rho = -0.18; p = 0.05). Mean TC concentration was significantly lower at day 0 when all the patients were parasitaemic (3.0 ± 1.0 mmol/L) compared to day 3 (3.7 ± 1.2 mmol/L) (p = 0.01). Mean CT was low during the first week and at day 28, 71 (58.2%) children still had a subnormal CT levels. No relationship was found with the type of antimalarial drug. Transient hypertriglyceridemia and hypocholesterolemia are observed during the course of P. falciparum infection. High TG levels seem to be related to the malaria related haemolysis. Key words: Malaria, cholesterol, triglycerides, antimalarial, Gabon.

Introduction: Anaemia remains a major cause of poor health in children and pregnant women living in sub-Saharan Africa. Malaria is one of the main causes of anaemia in endemic countries. At the time of decreasing Plasmodium falciparum infection prevalence among children, it was essential to analyze the evolution of anaemia and severe malarial anaemia (SMA), the most frequent clinical manifestation of severe malaria, in Gabon. Methodology: Yearly recorded haemoglobin levels of febrile children aged below11 years, who benefitted from microscopic malaria diagnosis, were retrospectively analyzed to determine the evolution of anaemia and SMA prevalence throughout a nine-year period between 2000 and 2008. Results: Anaemia prevalence remained high both in P. falciparum-infected children (between 87.6% and 90.7%) and in uninfected children (between 73.5% and 82.6%). Although the risk of developing severe anaemia ranged between 1.9 [0.9-3.8] in 2000 and 3.0 [1.3-6.5] in 2007, SMA prevalence did not significantly change during the study period, varying from 6.0% to 8.0%. From 2001, the frequency of SMA was comparable between children younger than five years of age and children older than five years of age. Conclusions: The decreasing malaria prevalence previously observed in Gabon between 2000 and 2008 was not associated with a significant reduction of anaemia and SMA burden among children. Furthermore, other factors such as nutritional deficiencies, which may not be negligible, must be investigated in this vulnerable population

A total of 415 samples from febrile children exhibiting either concordant (n = 108) or discordant (n = 307) results between microscopy, the gold standard diagnostic test, and two Rapid Diagnostic Tests (RDTs), OptiMAL-IT?(pLDH) and Acon?HRP2, were analysed using polymerase chain reaction (PCR) from May to December 2011 in Gabon. The aim of the study was to analyse these discrepancies using poly-merase chain reaction (PCR). Nested PCR targeting the Plasmodium ssrRNA gene was used to distinguish P. falciparum, P. malariae and P. ovale. Plasmodium falciparum was the only malaria species identified. Discrepancies frequently involved samples that were negative by microscopy and positive by Acon?HRP2 (90%) or Optimal-it?(86%). The PCR assay detected submicroscopic infection in almost 23% of the microscopy-negative samples, whereas plasmodial DNA was not found in 77% of the Acon?HRP2 positive-microscopy negative samples. Although results obtained with Optimal-it? were more frequently concordant with those of PCR genotyping, the low specificity of Optimal-iT?for non-falciparum malaria parasite detection resulted in a high proportion of false negative RDTs (90%) and a high frequency of tests with faint line intensity. The present study highlights the specific attributes of the different methods used to identify malaria parasite below the microscopy level of detection. RDT results that were discordant with either microscopy or PCR as the gold standard could represent a challenge for rapid, accurate fever case management in malaria endemic areas. It is necessary to pursue the development of more precise and more sensitive point-of-care diagnostic tools for malaria.

BACKGROUND Six years after the implementation of intermittent preventive treatment in pregnancy (IPTp) with sulfadoxine-pyrimethamine (SP) in Gabon, its impact on placental malaria and pregnancy outcomes remains unknown. METHODS Age, gestational data, use of IPTp-SP and birth weight were recorded during a hospital-based cross-sectional survey performed in 2011 in 387 women at the end of pregnancy. RESULTS Malaria prevalence was 6.7 and 5.3% in peripheral and placental blood respectively. Overall, 59.0% women took at least two IPTp-SP doses which was associated with 50% reduction of Plasmodium; (P.) falciparum infection in primigravidae. Previous malaria treatment was a risk factor for peripheral P. falciparum infection, while uptake of IPTp-SP was associated with reduced parasitaemia. Anaemia prevalence was 38.0%, low birth weight and prematurity rates were 6.0 and 12.0% respectively. Young age was associated with a higher frequency of malaria, anaemia, low birth weight and preterm delivery (p

Les resultats de trois enquetes, menees au centre hospitalier de Libreville au Gabon, chez 611 parturientes en 1995 ( n = 110), en 2005 ( n = 202) et en 2011 ( n = 299), nous ont permis de comparer la prevalence de l’infection plasmodiale et de l’anemie. La prevalence de l’infection a Plasmodium falciparum a diminue de 25 a 6 % dans le sang peripherique maternel. En tenant compte de la notion de chimioprophylaxie, aucune difference n’a ete retrouvee entre les parturientes dans la population totale. La prevalence de l’anemie est restee elevee (> 50 %) jusqu’en 2005, sans association avec l’infection plasmodiale, ni a la parite. Elle a diminue de moitie en 2011 (24 %). Apres le deploiement des nouvelles mesures preventives du paludisme au cours de la grossesse, les prevalences de l’infection plasmodiale peripherique maternelle et de l’anemie ont diminue. Des etudes complementaires evaluant l’efficacite de ces nouvelles mesures sont necessaires.

International audience; The new recommendations to prevent malaria in pregnant women have recently been implemented in Gabon. There is little information on the pregnancy indicators that are useful for their evaluation. A cross-sectional study for the assessment of the prevalence of peripheral, placental, and cord malaria and anemia among delivering women was performed at the largest public hospital of Gabon. Malaria prevalence was 34.4%, 53.6%, and 18.2% for maternal peripheral, placental, and cord blood respectively, with no difference between primigravidae and multigravidae. Submicroscopic infections were frequent and concerned all the positive cord samples. Maternal peripheral, late placental, and cord infections were all associated with a reduced mean birth weight in primigravidae (P = 0.02). Anemia prevalence was 53%, low birth rate was 13%, and prematurity was 25%. The use of intermittent preventive treatment with sulfadoxine-pyrimethamine (greater than or equal to one dose) combined with bed net was associated with a reduction in infection only in multigravidae and with a reduced risk of maternal anemia.

The frequency of dhfr and dhps point mutations was assessed in Plasmodium falciparum isolates from pregnant women in Libreville.PCR-restriction fragment length polymorphism of polymorphic codons of the dhfr gene (51, 59 and 108) and the dhps gene (436, 437 and 540) was performed in matched peripheral and placental blood samples.The proportion of multiple mutations was high (98%), and was not different between women with and without a history of intermittent preventive treatment with sulfadoxine/pyrimethamine (IPTp/SP). The prevalence of triple dhfr mutation was 80%, and that of quadruple and quintuple mutations was 53% and 22%, respectively. The Glu540 mutation was present in two isolates. The concordance of resistant alleles in matched peripheral and placental isolates was90% for both genes.These findings underline the need for a regular assessment of the relationship between the presence of resistant isolates and in vitro/in vivo IPTp/SP efficacy, and evaluation of an alternative drug.

Background Current artesunate (ARS) regimens for severe malaria are complex. Once daily intramuscular (i.m.) injection for 3 d would be simpler and more appropriate for remote health facilities than the current WHO-recommended regimen of five intravenous (i.v.) or i.m. injections over 4 d. We compared both a three-dose i.m. and a three-dose i.v. parenteral ARS regimen with the standard five-dose regimen using a non-inferiority design (with non-inferiority margins of 10%). Methods and Findings This randomized controlled trial included children (0.5–10 y) with severe malaria at seven sites in five African countries to assess whether the efficacy of simplified three-dose regimens is non-inferior to a five-dose regimen. We randomly allocated 1,047 children to receive a total dose of 12 mg/kg ARS as either a control regimen of five i.m. injections of 2.4 mg/kg (at 0, 12, 24, 48, and 72 h) (n = 348) or three injections of 4 mg/kg (at 0, 24, and 48 h) either i.m. (n = 348) or i.v. (n = 351), both of which were the intervention arms. The primary endpoint was the proportion of children with ≥99% reduction in parasitemia at 24 h from admission values, measured by microscopists who were blinded to the group allocations. Primary analysis was performed on the per-protocol population, which was 96% of the intention-to-treat population. Secondary analyses included an analysis of host and parasite genotypes as risks for prolongation of parasite clearance kinetics, measured every 6 h, and a Kaplan–Meier analysis to compare parasite clearance kinetics between treatment groups. A post hoc analysis was performed for delayed anemia, defined as hemoglobin ≤ 7g/dl 7 d or more after admission. The per-protocol population was 1,002 children (five-dose i.m.: n = 331; three-dose i.m.: n = 338; three-dose i.v.: n = 333); 139 participants were lost to follow-up. In the three-dose i.m. arm, 265/338 (78%) children had a ≥99% reduction in parasitemia at 24 h compared to 263/331 (79%) receiving the five-dose i.m. regimen, showing non-inferiority of the simplified three-dose regimen to the conventional five-dose regimen (95% CI −7, 5; p = 0.02). In the three-dose i.v. arm, 246/333 (74%) children had ≥99% reduction in parasitemia at 24 h; hence, non-inferiority of this regimen to the five-dose control regimen was not shown (95% CI −12, 1; p = 0.24). Delayed parasite clearance was associated with the N86YPfmdr1 genotype. In a post hoc analysis, 192/885 (22%) children developed delayed anemia, an adverse event associated with increased leukocyte counts. There was no observed difference in delayed anemia between treatment arms. A potential limitation of the study is its open-label design, although the primary outcome measures were assessed in a blinded manner. Conclusions A simplified three-dose i.m. regimen for severe malaria in African children is non-inferior to the more complex WHO-recommended regimen. Parenteral ARS is associated with a risk of delayed anemia in African children. Trial registration Pan African Clinical Trials Registry PACTR201102000277177, In a randomized trial, Sanjeev Krishna and colleagues test for non-inferiority of a simplified artemisinin regimen as treatment for malaria in a low-resource setting., Editors' Summary Background Globally, about 200 million cases of malaria—a mosquito-borne parasitic disease—occur every year. Malaria infections, which can be caused by several parasites, can be “uncomplicated” or “severe.” Prompt treatment of uncomplicated malaria, which presents with flu-like symptoms, is essential to prevent the development of severe malaria. The World Health Organization (WHO) recommends artemisinin combination therapy (ACT) for the first-line treatment of uncomplicated malaria in countries where the disease is always present. In ACT, artemisinin derivatives (fast-acting antimalarial drugs that are cleared rapidly from the body) are combined with a slower-acting, more slowly eliminated partner drug to prevent the original infection recurring and to reduce the risk of the malaria parasites becoming resistant to either drug. Severe malaria, which is usually caused by Plasmodium falciparum, is characterized by anemia and by damage to the brain and other organs. Severe malaria kills more than 400,000 people (mainly young children living in sub-Saharan Africa) every year. Why Was This Study Done? WHO recommends that severe malaria be treated with intravenous or intramuscular injections of artesunate, a parenteral (injectable) form of artemisinin; patients with severe malaria cannot take pills reliably or safely. Specifically, WHO recommends that patients be given 2.4 mg of artesunate per kilogram of body weight intravenously or intramuscularly at the time of admission (0 hours) and at 12, 24, 48, and 72 hours (followed by ACT to ensure full parasite clearance). But this five-dose regimen is complex. A simpler regimen would be easier to administer in resource-limited settings, where giving the correct doses on time to small, sick children can be challenging. In this open-label, non-inferiority randomized controlled trial (RCT), the researchers investigate the efficacy of a three-dose artesunate regimen for the treatment of severe malaria in African children. RCTs compare outcomes in people randomly chosen to receive different interventions; in an open-label RCT, both the researchers and the participants know which treatment is being given; a non-inferiority trial investigates whether one treatment is not worse than another treatment. What Did the Researchers Do and Find? The researchers randomly allocated 1,047 children aged six months to ten years with severe malaria attending seven clinical centers in five African countries to receive a total dose of 12 mg of artesunate per kilogram of body weight as five intramuscular injections of 2.4 mg/kg given at 0, 12, 24, 48, and 72 hours (the control regimen) or as three intramuscular or intravenous injections of 4 mg/kg given at 0, 12, and 24 hours (three-dose intramuscular and intravenous regimens, respectively). The trial’s primary endpoint was the proportion of children whose parasitemia (parasite count in the blood) at 24 hours was ≤1% of that at admission (in other words, ≥99% parasite clearance). Among the 1,002 children who received the planned drug doses (the per-protocol population), 78% in the three-dose intramuscular group had ≥99% parasite clearance compared to 79% in the five-dose intramuscular group, a result that met a preset criterion for non-inferiority at 24 hours of the three-dose intramuscular regimen to the control regimen. However, because only 74% of the children in the three-dose intravenous group had ≥99% parasite clearance, this regimen was not shown to be non-inferior to the conventional five-dose regimen. What Do These Findings Mean? These findings when combined with the findings of several secondary analyses suggest that, in African children, a three-dose intramuscular artesunate regimen is non-inferior to the WHO-recommended regimen for the treatment of severe malaria. The study’s open-label design may limit the accuracy of its findings, as may its use of a primary endpoint midway through drug treatment rather than at the end (the researchers note that 60% of deaths from severe malaria occur during the first 24 hours of illness and that parasitemia is harder to measure later during treatment) and its use of parasite clearance rather than death as the primary endpoint (case fatality rates in severe malaria treatment trials are very low, so a much larger study would be needed if death were used as the primary endpoint). Overall, these findings support the use of the three-dose intramuscular artesunate regimen for the treatment of severe malaria. Importantly, however, 22% of the children in the study developed delayed anemia, irrespective of treatment regimen. Thus, although further studies are needed to clarify whether treatment with artesunate or the malaria infection itself was responsible for the delayed anemia, patients treated with artesunate for severe malaria should be routinely monitored for this complication. Additional Information This list of resources contains links that can be accessed when viewing the PDF on a device or via the online version of the article at http://dx.doi.org/10.1371/journal.pmed.1001938. Information is available from the World Health Organization on malaria (in several languages); the World Malaria Report 2014 provides details of the current global malaria situation, including information on malaria in individual African countries; WHO’s Guidelines for the Treatment of Malaria and its Management of Severe Malaria: A Practical Handbook are available The US Centers for Disease Control and Prevention provides information on malaria (in English and Spanish), including personal stories about malaria The UK National Health Service Choices website also provides information about malaria, including a personal story Information is available from the Roll Back Malaria Partnership on the global control of malaria The Scientists Against Malaria collaboration applies modern drug design and modeling techniques to develop new treatments against malaria; its website includes information about many aspects of malaria Public Health England provides a collection of guidance and research and analysis on malaria MedlinePlus provides links to additional information on malaria (in English and Spanish) More information about this trial is available

We assessed Plasmodium (P.) falciparum allelic diversity based on clinical severity and age. The study was conducted from 2011 to 2012 in Libreville, Gabon where malaria prevalence was 24.5%. The polymorphism of the merozoite surface protein-1 (msp1) locus was analyzed in isolates from patients with complicated and uncomplicated malaria. Blood was collected on filter paper. After DNA extraction, genotyping of the msp1 gene was performed using nested PCR. The K1, Ro33, and Mad20 allelic families were detected in 71 (63%), 64 (57%), and 38 (34%) of the 112 analyzed samples, respectively. Overall, 17 K1 and 11 Mad20 alleles were detected. There was no association between msp1 allelic families and age. Mad20 allelic diversity increased with the severity of malaria. The number of K1 and Mad20 alleles decreased with age. The multiplicity of infection (MOI) was 1–6 genotypes and the complexity of infection (COI) 1.8 ± 1. The COI differed based on age: it was 1.9 (±1.1) in the isolates from adults, 1.8 (±1.1) in those from 0–5 year-old children, whereas it tended to be lower (1.6 ± 0.8) in those from 6–15 year-old children. Extensive genetic diversity is found in P. falciparum strains circulating in Libreville. The number of specific msp1 alleles increased with clinical severity, suggesting an association between the diversity and the severity of malaria.

Item does not contain fulltext 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 cell-mediated cytotoxicity against Plasmodium falciparum-infected 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. falciparum-infected 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. falciparum-infected erythrocytes is correlated with high cortisol concentrations and may contribute to increased susceptibility to malaria during pregnancy.

This study analyzed the relationship between intermittent preventive treatment with sulfadoxine-pyrimethamine (SP) (IPTp-SP), the rate of multiple resistant parasites and of submicroscopic gametocyte carriage among pregnant women at the beginning of IPTp implementation in Gabon (2005) and six years after (2011). The detection of pfdhfr and pfdhps gene mutations was performed by PCR-RFLP in Plasmodium (P.) falciparum positive samples collected from pregnant women in 2005 and 2011. Gametocytes carriage was detected by Pfs25mRNA amplification using QT-NASBA. Data were analyzed according to the time of collection (study period) and IPTp-SP doses. The proportion of isolates with at least a triple Pfdhfr mutation (n = 39/42, 92.9% versus 100%, n = 78/78)) and of those isolates with the S108N/C59R/N51I/S436A/A437G multiple mutation (17.9% versus 75.6%) significantly increased between 2005 and 2011 (p

Mutations in the Plasmodium falciparum K13-propeller domain have recently been shown to be important determinants of artemisinin resistance in Southeast Asia. This study investigated the prevalence of K13-propeller polymorphisms across sub-Saharan Africa. A total of 1212 P. falciparum samples collected from 12 countries were sequenced. None of the K13-propeller mutations previously reported in Southeast Asia were found, but 22 unique mutations were detected, of which 7 were nonsynonymous. Allele frequencies ranged between 1% and 3%. Three mutations were observed in >1 country, and the A578S was present in parasites from 5 countries. This study provides the baseline prevalence of K13-propeller mutations in sub-Saharan Africa.

Following the observed increase of malaria prevalence among older children in Gabon, a descriptive observational study was carried out in 2012 to determine the prevalence of malaria in adults presenting with fever in two health centres of Libreville, the capital city of Gabon. Thick- and thin-blood smears for malaria diagnosis were performed in febrile individuals aged more than 15 years old. Age, use of bed nets, previous antimalarial drug treatment, clinical symptoms, chest radiography results, and available haemoglobin data were also recorded. Among the 304 patients screened, the global malaria frequency was of 42.1%(n=128/34).Plasmodium (P). falciparumwas the only species identified. The proportion of patients with a clinical malaria requiring parenteral treatment was 38.5%, whereas 47.5% of outpatients had uncomplicated malaria. According to WHO classification, 14 (19.7%) infected patients had severe malaria; neurological and respiratory symptoms tended to be more frequent in case ofP. falciparuminfection. Anaemia was found in 51.5% adults and none had severe anaemia. Almost half of adults consulting for fever in two health centres of the urban city of Libreville have malaria. The use of insecticide-treated bed nets, the screening, and the treatment of individuals withP. falciparummicroscopic and submicroscopic asymptomatic infection or clinical malaria should be emphasized to reduce the transmission.

Submicroscopic infections account for more than 50% of all Plasmodium (P.) infections in areas with decreasing malaria prevalence and might contribute to poor pregnancy outcomes. The frequency of submicroscopic P. falciparum infections was assessed in matched peripheral and placental blood samples with microscopy negative or discordant results according to IPTp administration. Methods. P. falciparum infection was detected by nested PCR in matched blood samples collected from delivering women with a history of antimalarial drug treatment and living in Gabon. Results. Submicroscopic P. falciparum infections were detected in 87% (n=33) of the 44 selected matched samples. Plasmodial DNA was found in 90% (n=35/39) and 87% (n=33/38) of microscopy negative peripheral and placental blood samples, respectively. Overall, 95% of samples obtained during the high IPTp-SP coverage period had a submicroscopic infection versus 79% among those from the low coverage period. Conclusion. Submicroscopic infections frequency is high in peripheral and placental blood samples from delivering women with a history of antimalarial treatment whatever the level of IPTp coverage. These data highlight the need of accurate diagnostic tools for a regular antenatal screening of malaria during the pregnancy in endemic areas.

Background Considering malaria prevalence declines in parts of sub-Saharan Africa, such as Gabon, identification of the human infectious reservoir is important for successful malaria control. Microscopic and sub-microscopic parasites contribute to malaria transmission. The aim of the present study was to evaluate the proportion of microscopic and sub-microscopic gametocyte carriers among febrile patients in two different areas of Gabon. Methods Samples from febrile children aged less than 11 years old were collected from February 2008 to January 2009 at two health centres of Gabon. Patients were screened for the presence of asexual Plasmodium falciparum parasites. Gametocyte carriage was determined by microscopy and QT-NASBA. Results Gametocytes were detected in 5.3% (n = 16/304) of children by microscopy compared to 45.7% (n = 139/304) by QT-Nasba. Sub-microscopic gametocyte carriage (ie microscopy negative and QT-Nasba positive) was found in 89.2% (n = 124/139) of patients. Among patients with microscopically detected trophozoites, the proportion of sub-microscopic gametocyte (SMG) carriers was 58.4% (n = 118/202) and 6% in samples from children with negative slides (p < 0.01). In Oyem, where malaria prevalence is three-fold higher than in Owendo, SMG carriage was more frequent (49.0% vs 32.6% in Owendo; p < 0.01). Conclusion Sub-microscopic gametocytaemia is common among Gabonese febrile children. They might strongly contribute to maintain malaria transmission. However, further analysis of sub-microscopic parasite carriage among asymptomatic individuals will be helpful to better characterize malaria transmission.

Background The World Health Organization (WHO) recommends that intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-SP) and insecticide treated bed nets (ITNs) must be provided during antenatal care (ANC) visits for malaria prevention during pregnancy. The aim of this study was to determine the level of ANC attendance and its relationship with IPTp-SP and bed net coverage in Gabonese pregnant women. Methods This was a cross-sectional survey performed in 2011 in sentinel sites for malaria: two ANC units (Melen and Owendo) and one delivery unit (CHL). A validated structured questionnaire was used to collect the following data: age, parity, history of the current pregnancy including gestational age at the interview, number of ANC visits already performed, date of first visit, use of malaria preventive measure and details on IPTp-SP administration. Results During the study, 1030 women were interviewed, 735 at their ANC visit and 295 at the delivery. Their median age was 24[20–29] years and 21.0% were primigravidae. More than 70.0% attended their first ANC visit during the second trimester. Among the 442 women who were at the end of their pregnancy, 71.5% had a correct attendance, at least four ANC visits, most frequently women with no education and older women; IPTp-SP was offered to 84.1% of them and 57.4% received at least two doses. The number of SP doses was correlated to the number of ANC visits. Bed net coverage was 59.0%, not associated with ANC attendance. Among the women with correct ANC attendance, only 49.5% had a complete IPTp-SP course associated with bed net use during pregnancy. In the site where SP administration was supervised, 80% had four ANC visits and 97.4% received a full 2-dose course of IPTp-SP. Conclusions Despite a high level of correct ANC attendance in Gabon, the goal of 80% of women with 2-dose IPTp-SP during pregnancy is not achieved. Evaluations, training of health workers, as well as surveys from other areas of the country are needed to further measure the implementation and the impact of these strategies.

Background Although a substantial decline of Plasmodium falciparum infection is observed in Africa following implementation of new control strategies, malaria is still considered as the major cause of febrile illness in hospitalized African children. The present study was designed to assess the management of febrile illness and to determine the proportion of children with febrile illness hospitalized for primary diagnosis of malaria who had confirmed complicated malaria after implementation of new malaria control strategies in Libreville, Gabon. Methods Demographic, clinical and biological data from hospitalized children with fever or a history of fever, with a primary diagnosis of clinical malaria, aged less than 18 years old, who benefited from hematological measurements and microscopic malaria diagnosis, were recorded and analyzed during a prospective and observational study conducted in 2008 in the Centre Hospitalier de Libreville. Results A total of 418 febrile children were admitted at hospital as malaria cases. Majority of them (79.4%) were aged below five years. After medical examination, 168 were diagnosed and treated as clinical malaria and, among them, only 56.7% (n = 95) had Plasmodium falciparum positive blood smears. Age above five years, pallor, Blantyre Coma Score ≤2 and thrombocytopenia were predictive of malaria infection. Respiratory tract infections were the first leading cause of hospitalization (41.1%), followed by malaria (22.7%); co-morbidities were frequent (22%). Less than 5% of suspected bacterial infections were confirmed by culture. Global case fatality rate was 2.1% and 1% for malaria. Almost half (46%) of the children who received antimalarial therapy had negative blood smears. Likewise, antibiotics were frequently prescribed without bacteriological confirmation. Conclusions The use of clinical symptoms for the management of children febrile illness is frequent in Gabon. Information, training of health workers and strengthening of diagnosis tools are necessary to improve febrile children care.

Resistance by Plasmodium falciparum to antimalarial drugs has strongly hampered strategies for malaria control and elimination. Therefore, one of the goals of the World Health Organisation's new malaria control strategies is the rational and appropriate use of antimalarial drugs and in particular of artemisinin-based combination therapy (ACTs), currently used for the treatment of uncomplicated malaria; in order to delay the appearance of drug-resistant parasites. The unprescribed use of antimalarial drugs (self medication and parental administration to children) is a key component in the development of antimalarial drug resistance and must be controlled among patients living in malaria-endemic areas. The aim of our study was to estimate the frequency of this parental administration among febrile children and to identify the specific drugs used. Data were collected in two studies evaluating the proportion of malaria cases and the performance of rapid drug tests among febrile children seen in 2008-2009 at 3 hospitals, one in a rural area, one in an urban area, and the third in a semi-urban area. This parental medication administration was found among 21.4% of the 2543 children included in the studies. It was most common at the rural hospital (29%), which is also where malaria prevalence was highest (39%). Of the 548 children "medicated", 421, that is, almost 80%, were not infected. The antimalarial drugs used most frequently were ACTs (43.8%) and quinine (12%). In Gabon, as in other sub-Saharan countries, use of antimalarial drugs before consultation is common and is an obstacle to malaria control. Therefore, improving the rational use of these drugs by the population requires active outreach to the community about the risks of unprescribed medication.

The African continent continues to bear the greatest burden of malaria and the greatest diversity of parasites, mosquito vectors, and human victims. The evolutionary plasticity of malaria parasites and their vectors is a major obstacle to eliminating the disease. Of current concern is the recently reported emergence of resistance to the front-line drug, artemisinin, in South-East Asia in Plasmodium falciparum , which calls for preemptive surveillance of the African parasite population for genetic markers of emerging drug resistance. Here we describe the Plasmodium Diversity Network Africa (PDNA), which has been established across 11 countries in sub-Saharan Africa to ensure that African scientists are enabled to work together and to play a key role in the global effort for tracking and responding to this public health threat.

International audience; Pediatric drug formulations of artemisinin combination therapies are urgently needed for improving the treatment of children suffering from uncomplicated malaria. The aim of this clinical trial was to evaluate the efficacy, safety and tolerability of a novel pediatric fixed-dose granule formulation of artesunate-mefloquine and a new co-blister tablet formulation. A total of 71 children aged 1-13 years suffering from uncomplicated falciparum malaria were stratified into two groups according to weight: 10-20 kg, pediatric group (n = 41); 20-40 kg, tablet group (n = 30). All the children were treated once daily for three days: the pediatric group received the novel granule formulation, the tablet group received the co-blister tablets. The PCR-corrected cure rate on day 28 was evaluated. There was no reappearance of parasitemia during the follow-up period and the day-28 cure rate was therefore 100% in per-protocol analysis. In intention-to-treat analysis the cure rates were 95% in the pediatric group and 97% in the tablet group. The most frequent adverse events were vomiting (17%), abdominal pain (11%) and headache (17%). This study confirms the excellent efficacy and favorable safety and tolerability profile of a novel pediatric artesunate-mefloquine formulation for treatment in African children.

The ability of natural killer (NK) cells to produce gamma interferon (IFN-gamma) after ex vivo stimulation with crude schizont lysate of Plasmodium falciparum was studied in uninfected and P. falciparum-infected pregnant Gabonese women segregated according to the gravidity at the time of delivery. This activity was measured in purified NK cells as well as in whole blood from the periphery and cord. Crude schizont lysate-stimulated NK cells from primiparous women produced significantly more IFN-gamma than those from multiparous women (P0.001). Women with malaria infection produced more IFN-gamma than negative women in peripheral blood (P0.001) indicating that immunological determinants regulating the susceptibility to malaria in pregnant women are parasite-specific. These findings reveal that NK cells are major source of IFN-gamma when exposed to P. falciparum antigens in vitro in absence of any other co-stimulant.

Background Improving the understanding of childhood malarial anaemia may help in the design of appropriate management strategies. Methods A prospective observational study over a two-year period to assess the burden of anaemia and its relationship to Plasmodium falciparum infection and age was conducted in 8,195 febrile Gabonese children. Results The proportion of children with anaemia was 83.6% (n = 6830), higher in children between the ages of six and 23 months. Those under three years old were more likely to develop moderate to severe anaemia (68%). The prevalence of malaria was 42.7% and P. falciparum infection was more frequent in children aged 36–47 months (54.5%). The proportion of anaemic children increased with parasite density (p < 0.01). Most of infected children were moderately to severely anaemic (69.5%, p < 0.01). Infants aged from one to 11 months had a higher risk of developing severe malarial anaemia. In children over six years of age, anaemia occurrence was high (>60%), but was unrelated to P. falciparum parasitaemia. Conclusion Malaria is one of the main risk factors for childhood anaemia which represents a public health problem in Gabon. The risk of severe malarial anaemia increases up the age of three years. Efforts to improve strategies for controlling anaemia and malaria are needed.

Objectives Paediatric drug formulations of artemisinin combination therapies and pharmacokinetic data supporting their use in African children are urgently needed for the effective treatment of young children suffering from falciparum malaria in sub-Saharan Africa. Patients and methods In this study, the pharmacokinetic characteristics of a novel paediatric granule formulation of artesunate-mefloquine therapy were evaluated in comparison to the standard tablet formulation in the treatment of uncomplicated malaria in paediatric patients. Twenty-four patients were assigned to treatment according to body weight with either a fixed-dose paediatric granule co-formulation (10-20 kg body weight) or a free-dose co-blister tablet formulation of artesunate-mefloquine (>20-40 kg body weight). Results Median values for C(max) (861 and 930 ng/mL), T(max) (1.5 and 1.5 h) and AUC(0-)(t) (2,050 and 2,470 ng.h/mL) were comparable for dihydroartemisinin in the two groups. Exploratory analysis of mefloquine plasma levels revealed a trend towards higher concentrations in the younger age group during the absorption phase (2,550 and 1,815 ng/mL, 54 h after initiation of treatment, respectively). Median mefloquine concentrations at day 28 were 197 and 343 ng/mL, respectively. Conclusions The pharmacokinetic characteristics of the two paediatric dosage forms, i.e. the novel fixed-dose co-formulation and the standard co-blister of artesunate-mefloquine show comparable results in the two treatment groups. The novel fixed-dose paediatric formulation is an interesting option for outpatient treatment of uncomplicated malaria in African children.

Intermittent preventive treatment in pregnancy (IPTp) with sulfadoxine–pyrimethamine has recently been adopted by many African countries to reduce maternal and neonatal morbidity and mortality associated with malaria in pregnancy. We assessed the impact of a newly established national IPTp program on maternal and neonatal health in Gabon. Data on prevalence of maternal Plasmodium falciparum infection, anemia, premature birth, and birth weight were collected in cross-sectional surveys in urban and rural regions of Gabon before and after the implementation of IPTp in a total of 1403 women and their offspring. After introduction of IPTp, the prevalence of maternal Plasmodium falciparum infection decreased dramatically (risk ratio 0.16, P < 0.001). Whereas only a modest effect on the rate of anemia in pregnant women was observed, there was a marked benefit on the prevalence of low birth weight and premature birth for women adhering to national recommendations. These effects were most pronounced in primi- and secundigravid women.

In areas where malaria transmission is stable, infants are often born to mothers who had Plasmodium falciparum infections during pregnancy. A significant number become exposed to infected erythrocytes or soluble parasite products with subsequent fetal immune priming or tolerance in utero. We performed ELISA to asses IgG and IgM seropositivity rates against three PfEMP1 DBL-alpha domains from 42 maternal-cord paired samples obtained at delivery from a hyperendemic area in Gabon. IgG was present in up to 80% of the cord serum samples, while IgM was found in only 20% of the same samples. These levels were not dependent on the parity of the mother or the peripheral and placental infectious status. The presence of IgM against DBL-alpha domain in cord serum samples suggests that this component is able to cross the placental barrier and mount a fetal immune response.

SummaryThe surface density of the triggering receptors (e.g. NKp46 and NKp30) responsible for natural killer (NK) cell-mediated cytotoxicity determines the ability of NK cells to kill susceptible target cells. In this study, we show that prolactin up-regulates and cortisol down-regulates the surface expression of NKp46 and NKp30. The prolactin-mediated activation and the cortisol-mediated inhibition of natural cytotoxicity receptor (NCR) surface expression reflects gene regulation at the transcriptional level. NKp46 and NKp30 are the major receptors involved in the NK-mediated killing of K562, a human chronic myelogenous leukaemia cell line. Accordingly, the prolactin dramatically increased the NK-mediated killing of the K562 cell line, whereas cortisol abolished this activity. Our data suggest a mechanism by which prolactin activates the lytic function of NK cells, and cortisol inhibits the NK-mediated attack.

We measured cortisol and prolactin concentrations in the peripheral venous blood of 23 non-pregnant and 59 pregnant Gabonese women from the second trimester of pregnancy until delivery. Cortisol concentrations were significantly higher in primigravidae women than in multigravidae women between 20 and 25 weeks' gestational age (166 vs. 132 ng/ml, respectively), between 28 and 37 weeks (226 vs. 161 ng/ml) and at delivery (287 vs. 188 ng/ml). Conversely, plasma prolactin levels were highest in multigravidae women. Cortisol and prolactin concentrations both increased with the period of pregnancy (P = 0.01 and P < 0.01, respectively), suggesting that a sustained increase in cortisol level underlies the increased susceptibility of pregnant women, particularly primigravidae women, to malaria. In support of this hypothesis, we found a significant association between cortisol concentration and Plasmodium falciparum infection, on the one hand, and strong correlations with parasite load in P. falciparum-infected primigravidae women, on the other hand (rho between 0.35 and 0.45 with P < 0.01).

During gestation, inflammatory cytokines are sometimes more abundant than growth-promoting cytokines, and via direct or indirect effects, proinflammatory cytokines lead to intrauterine growth retardation. We used an enzyme-linked immunosorbent assay to measure the concentrations of three proinflammatory cytokines, tumor necrosis factor alpha (TNF-alpha), interleukin-12 (IL-12p40), as well as interleukin-15 (IL-15) and monocyte chemotactic protein-1 (MCP-1), in plasma from peripheral, placental and cord blood of thirty pregnant Gabonese women. All of these women lived in Libreville and Lambaréné, two malaria hyperendemic areas. IL-12p40 concentrations were higher in cord blood than in placental or peripheral blood. The MCP-1 concentration was higher in placental blood, than in peripheral or cord blood. IL-15 concentrations were similar at the three sites. MCP-1 concentrations were higher in the placentas of primiparous women than in those of multiparous women. The highest concentrations were found in infected placentas. IL-15 concentrations were significantly higher in peripheral and placental plasma from uninfected women than in plasma from infected women. Strong positive correlations were found between placental and cord IL-12p40 and IL-15 plasma concentrations. Likewise, a strong positive correlation was found between IL-12p40 and MCP-1 concentrations in cord and peripheral plasma. These results suggest that placental, maternal peripheral and cord blood present different cytokine profiles in response to P. falciparum.

0 d Malaria caused byPlasmodium falciparum is a major pubic health problem with significant economic and social conequences for many developing countries. Estimates of global ncidence of the disease range from 300 to 500 million cases er year, with up to 2.7 million deaths, primarily children in frica [1,2]. Despite years of intensive research, an effective accine is not available and the parasite displays growing esistance to currently available drugs. Rapid progress in geomic research, of the human malaria parasite P. falciparum 3], has stimulated basic research by creating the basis for the dentification and study of parasite proteins that can be used s targets for new drugs and vaccine development. In view f a vaccine for malaria, the construction of a multivalent ubunit vaccine is being considered a major way forward. he selection of protein antigens for such a vaccine has been ampered by the lack of a reliably and readily accessible hallenge system for P. falciparum. Efforts to identify plasodial antigens that trigger protective responses have and ill continue to benefit from studies of rodent malaria parsites [4]. Although, it is argued that these models are quite ifferent from the human system, it is, however, generally agreed that studies in these models can give valuable information in selecting vaccine candidates. The P. yoelii and P. chabaudi models have been effectively used to investigate immunity against blood stage parasites [5,6]. In related studies, two highly enriched membrane proteins of P. yoelii were shown to mediate protective immunity in mice [7,8]. Further studies implicated specific antigens termed pypAg-1 and pypAg-3 characterised by tryptophanrich domains. In a recent study, we identified and characterised a P. falciparum homologue of pypAg-1. Based on its amino acid sequence, we termed it Tryptophan–Threoninerich Antigen (TryThrA), that has typical characteristics of an exported P. falciparum protein [9]. Further searching the malaria database predicted paralogues in P. falciparum. In this study, we identified and characterized the second member of this gene family, which has features similar to the pypAg-3 gene of P. yoelii, which we have termed Merozoiteassociated Tryptophan-rich Antigen (MaTrA). We have also investigated the natural immune responses of TryThrA and MaTrA using serum samples from semi-immune individuals from Lambarene, Gabon.