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Background: Chronic carriage of intestinal parasitic infections (IPIs) can induce chronic inflammation and dysbiosis, which are risk factors for non-communicable diseases. The objective of this study was to determine the relationship between IPI carriage and inflammation in a population of volunteers living in Gabon., Methodology and Principal Findings: A cross-sectional study was conducted from September 2020 to November 2021 in asymptomatic volunteers aged 18 years old and over, residing in different areas of Gabon: Libreville (urban area) and Koula-Moutou and Bitam (rural areas). The detection of IPIs was carried out using four common microscopic techniques. C-reactive protein (CRP), and high-sensitivity C-reactive protein (hsCRP) were measured and levels were compared according to the presence or absence of IPI. Overall, 518 participants were included, 64.5% (n = 334) of whom resided in urban area and 35.5% (n = 184) in rural areas. The median age was 35 years (27; 46). The prevalence of asymptomatic IPIs was 29.9% (n = 155), with a significantly higher frequency in rural areas than in urban area (adjusted OR 6.6 (CI 3.2-13.8), p < 0.01). Protozoa were more frequent than soil-transmitted helminths (STHs) in both areas: 81.6% (n = 40) in urban area and 69.8% (n = 74) in rural areas. STHs were predominant in rural areas (48.1% vs 22.4% in urban area. In case of IPI, the median values of CRP (15 (13-15) mg/L vs 13.0 (11.1-14.9) mg/L) and hsCRP (4.2 (1.4-13.0) mg/L vs 2.2(0.4-6.1) mg/L) were higher (p<0.01). Elevated hsCRP and CRP were significantly more frequent in parasitized individuals (for hsCRP: 22.6%, n = 35; for CRP: 52.9%, n = 82); in particular among STH carriers (for hsCRP: 65.9%, n = 27, for CRP: 36.6%, n = 15) (p < 0.01)., Conclusions/significance: This first study showed that asymptomatic IPIs, particularly STH carriage are associated with high CRP and hsCRP levels. Further larger and longitudinal studies are needed to elucidate the global and specie-specific enteropathogens link with chronic inflammation., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Kono et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: The prevalence of cardiometabolic risk factors (CMRFs) is increasing in sub-Saharan Africa and represents a serious public health issue. Accurate data are required to implement adapted prevention programs and healthcare strategies. Thus, the aim of this study was to estimate the prevalence rates of CMRFs according to the level of urbanization, age and gender in Gabon., Methods: A cross-sectional study was conducted in northern (Bitam), western coast (Libreville, Melen) and southeast (Koulamoutou) areas of Gabon using the World Health Organization's (WHO) stepwise approach for the surveillance of chronic disease risk factors. Participants over 18 years of age, without known underlying disease, living in rural and urban areas of Gabon were included. Sociodemographic, biological, and behavioral data were collected. Univariate and multivariate analysis were used to identify the CMRFs., Results: Of the 978 participants, 499 lived in urban and 479 in rural areas. Their median age was 38[28-50] years. Tobacco (26.1% vs 6.2%; p < 0.01) and excessive alcohol consumption (19.4% vs 9.6%; p < 0.01) predominated in rural than in urban areas, respectively. Urban dwellers had more often insufficient physical activity than rural people (29.5% vs 16.3%; p < 0.01). In total, 79.9% of participants aged under 54 years had a high blood pressure;10.6% of the younger participants had pre-hypertension. Metabolic syndrome was more frequent in women (21.7%) than in men (10.0%) (p < 0.01); 6.4% of men and 2.5% of women had a high Framingham score (p = 0.03). Finally, 54.0% of the participants had three or four CMRFs. The multivariate analysis showed that men were more likely to be smokers and to be at risk of pre-hypertension or high blood pressure (p < 0.01). Women were more likely to be obese or to have a metabolic syndrome (p < 0.01). Living in urban areas was also a risk factor for hypertension, diabetes, metabolic syndrome and high LDL cholesterol level., Conclusion: The prevalence of CMRFs was high in the study population. Disparities were observed according to urban and rural areas, gender and age. National prevention and healthcare strategies for cardiometabolic diseases in Gabon should consider these observed differences., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Mengome et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: The aim of this study was to determine performance indicators of thick blood smears of 50 µl (TBS-50), following the Standards for the Reporting of Diagnostic Accuracy Studies-Bayesian Latent Class Model (STARD-BLCM) guidelines. TBS-50 was compared with two common parasitological techniques-direct examination of 10 µl blood and a leukoconcentration of 5 ml-for the diagnosis of microfilaremic loiasis., Methods: The study population was recruited among patients of the Department of Parasitology-Mycology-Tropical Medicine over a period of 1 year. Age, sex, symptoms, and eosinophilia variables were recorded from laboratory registers and medical files. Direct examination of 10 µl of blood, TBS-50, and the leukoconcentration technique with 5 ml of blood were performed for each patient. The classical formula and BLCM were used to determine the diagnostic accuracy of the three techniques as well as the prevalence of microfilaremic loiasis. Three models were built within the framework of BLCM-the BLCM model I and alternative models II and III-for sensitivity analysis., Results: In total, 191 patients consented to be included. The direct blood examination and TBS-50 yielded comparable qualitative and quantitative results. Hence, they are reported together. The prevalence of Loa loa microfilaremia was 9.4% (95% CI 5.7-14.5; n = 18/191) with direct blood examination/TBS-50 and 12.6% [8.2-18.1] (n = 24/191) for leukoconcentration. Comparing TBS-50 with the leukoconcentration method using the classical formula, the sensitivity was 75.0% [53.3-90.2], specificity was 100.0% [97.8-100.0], the positive predictive value was 100.0% [81.5-100.0], and the negative predictive value was 96.5% [92.6-98.7]. The prevalence of microfilaremic loiasis was estimated at 9.7% [6.2-13.7] using BLCM model I. The outputs of BLCM model I showed sensitivity of 78.9% [65.3-90.3], specificity of 100.0% [99.3-100.0], a positive predictive value of 99.1% [87.2-100.0], and a negative predictive value of 93.0% [87.3-97.7] for direct blood examination/TBS-50., Conclusions: TBS-50 demonstrates low sensitivity relative to two other techniques. In one in five cases, the result will be falsely declared negative using these methods. However, this method can be deployed with limited funds., (© 2024. The Author(s).)

Background: Efficacy of sulfadoxine-pyrimethamine, the malaria chemoprophylaxis used in pregnant women, and in children when combined with amodiaquine, is threatened by the accumulation of mutations in the Plasmodium falciparum dihydropteroate synthase (pfdhps) and dihydrofolate reductase (pfdhfr) genes. Data on the prevalence of resistant alleles in central Africa and the new pfdhps I431V mutation, particularly associated with other mutations to form the pfdhps vagKgs allele, are scarce. We explored the frequency and geographical distribution of pfdhps and pfdhfr mutations in central Africa in 2014-18, and assessed the evolutionary origin of the vagKgs allele., Methods: Samples were collected at 18 health-care centres in seven countries (Angola, Cameroon, Central African Republic, Democratic Republic of the Congo, Gabon, Nigeria, and Republic of the Congo) from patients who showed possible symptoms of malaria between March 1, 2014, and Oct 31, 2018. Samples that were positive for P falciparum were transported to a laboratory in Toulouse, France, and genotyped. The frequency of pfdhfr and pfdhps mutations was studied in 1749 samples. Microsatellites in pfdhps flanking regions and whole-genome analysis compared with parasite genomes from the data-sharing network MalariaGEN were performed on samples carrying the vagKgs allele., Findings: Mapping of the prevalence of single nucleotide polymorphisms and corresponding alleles of pfdhfr and pfdhps showed a substantial spread of alleles associated with sulfadoxine-pyrimethamine resistance in central Africa during the 2014-18 period, especially an increase going west to east in pfdhps alleles carrying the K540E and A581G mutations. A high prevalence of the pfdhps I431V mutation was observed in Cameroon (exceeding 50% in the northern region) and Nigeria. Genomic analysis showed a recent African emergence and a clonal expansion of the most frequent pfdhps vagKgs allele., Interpretation: Reduced sulfadoxine-pyrimethamine efficacy due to increased resistance is a worrying situation, especially because the malaria transmission level is high in central Africa. Although the resistance phenotype remains to be confirmed, the emergence and spread of the vagKgs allele in west and central Africa could challenge the use of sulfadoxine-pyrimethamine., Funding: Toulouse Institute for Infectious and Inflammatory Diseases., Competing Interests: Declaration of interests We declare no competing interests., (Copyright © 2023 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 license. Published by Elsevier Ltd.. All rights reserved.)

To implement the appropriate strategies for scale-up interventions to eliminate onchocerciasis without severe adverse events, clinical and biological factors associated with loiasis were analyzed in onchocerciasis-endemic areas. Blood was collected from volunteers after examination by a physician. Detection of microfilariae and measurement of Ov16 IgG4 were performed using direct microscopic examination of blood and onchocerciasis rapid test detection, respectively. Areas with sporadic, hypoendemic, and hyperendemic onchocerciasis endemicity were found. Participants with microfilaremia were considered microfilaremic, and those without microfilaremia were seen as amicrofilaremic. Of the 471 study participants, 40.5% (n = 191) had microfilariae. Among them, Mansonella spp. was the most common (78.2%, n = 147), followed by Loa loa (41.4%, n = 79). The association between the two species represented 18.3% (n = 35). The specific immunoglobulins of Onchocerca volvulus were detected in 24.2% of participants (n = 87/359). Overall prevalence of L. loa was 16.8%. Hypermicrofilaremia was found in 3% (N = 14), and one participant had more than 30,000 microfilaremiae per milliliter. The frequency of L. loa did not vary according to the level of onchocerciasis transmission. Pruritus was the most common clinical sign (60.5%, n = 285) reported, mainly in microfilaremic participants (72.2%, n = 138/191). The prevalence of L. loa microfilaria in the study population was below the threshold at risk for the occurrence of serious side effects due to ivermectin. Clinical manifestations frequently observed could be exacerbated by microfilaremia in areas where onchocerciasis transmission is high.

The objective of this study was to analyze the relationship between the frequency of artemisinin-based combination (ACT) drug resistance molecular markers and clinical forms of P. falciparum malaria and parasitemia. A cross-sectional study was carried out between January and April 2014 at the Operational Clinical Research Unit of Melen in febrile children aged 12 to 240 months with a Plasmodium sp. infection. A total of 3 mL of peripheral blood collected from an EDTA tube was used for leukocyte depletion. DNA mutation detection was performed by next generation sequencing (NGS). A total of 1075 patients were screened for malaria. Among them, 384 had a Plasmodium infection. P. falciparum mono-infection was found in 98.9% of the patients. Pfcrt -326T mutation was found in all isolates, while 37.9% had Pfmdr2 -484I mutant allele. The highest median parasite densities were found in patients infected by parasites carrying the CVIET haplotype of the Pfcrt gene. The different genetic profiles found here, and their variations according to clinical and biological signs of severe malaria, are additional arguments for the surveillance of P. falciparum strains.

Background: The contribution of artefenomel to the clinical and parasiticidal activity of ferroquine and artefenomel in combination in uncomplicated Plasmodium falciparum malaria was investigated., Methods: This Phase 2a, randomized, open-label, parallel-group study was conducted from 11th September 2018 to 6th November 2019 across seven centres in Benin, Burkina Faso, Gabon, Kenya, and Uganda. Patients aged ≥ 14-69 years with microscopically confirmed infection (≥ 3000 to ≤ 50,000 parasites/µL blood) were randomized 1:1:1:1 to 400 mg ferroquine, or 400 mg ferroquine plus artefenomel 300, 600, or 1000 mg, administered as a single oral dose. The primary efficacy analysis was a logistic regression evaluating the contribution of artefenomel exposure to Day 28 PCR-adjusted adequate clinical and parasitological response (ACPR). Safety was also evaluated., Results: The randomized population included 140 patients. For the primary analysis in the pharmacokinetic/pharmacodynamic efficacy population (N = 121), the contribution of artefenomel AUC 0-∞ to Day 28 PCR-adjusted ACPR was not demonstrated when accounting for ferroquine AUC 0-d28 , baseline parasitaemia, and other model covariates: odds ratio 1.1 (95% CI 0.98, 1.2; P = 0.245). In the per-protocol population, Day 28 PCR-adjusted ACPR was 80.8% (21/26; 95% CI 60.6, 93.4) with ferroquine alone and 90.3% (28/31; 95% CI 74.2, 98.0), 90.9% (30/33; 95% CI 75.7, 98.1) and 87.1% (27/31; 95% CI 70.2, 96.4) with 300, 600, and 1000 mg artefenomel, respectively. Median time to parasite clearance (Kaplan-Meier) was 56.1 h with ferroquine, more rapid with artefenomel, but similar for all doses (30.0 h). There were no deaths. Adverse events (AEs) of any cause occurred in 51.4% (18/35) of patients with ferroquine 400 mg alone, and 58.3% (21/36), 66.7% (24/36), and 72.7% (24/33) with 300, 600, and 1000 mg artefenomel, respectively. All AEs were of mild-to-moderate severity, and consistent with the known profiles of the compounds. Vomiting was the most reported AE. There were no cases of QTcF prolongation ≥ 500 ms or > 60 ms from baseline., Conclusion: The contribution of artefenomel exposure to the clinical and parasitological activity of ferroquine/artefenomel could not be demonstrated in this study. Parasite clearance was faster with ferroquine/artefenomel versus ferroquine alone. All treatments were well tolerated., Trial Registration: ClinicalTrials.gov, NCT03660839 (7 September, 2018)., (© 2023. The Author(s).)

Background: The level of blood filariasis parasitaemia as well as the frequency of and the relationship between cotrimoxazole prophylaxis (CTX-P), antiretroviral therapy (ART) intake and CD4 cell count among people living with human immunodeficiency virus (PLHIV) in rural areas of Gabon were being studied., Methods: Sociodemographic data and recent biological tests of PLHIV and HIV-negative participants were collected. Loa loa and Mansonella perstans microfilaria were detected by direct microscopy examination and leucoconcentration., Results: Overall, 209 HIV-positive and 148 HIV-negative subjects were enrolled. The overall prevalence of microfilaria was comparable between PLHIV (19.9% [n=41/206]) and HIV-negative participants (14.8% [n=22/148]) (p=0.2). The L. loa infection rate was comparable between HIV-positive (9.2%) and HIV-negative participants (6.8%) (p=0.2), while the M. perstans infection rate was 14-fold higher among PLHIV (p<0.01). L. loa parasitaemia was 6-fold lower in PLHIV receiving CTX-P (median 150 mf/mL [interquartile range {IQR} 125-350]) than in patients without (900 [550-2225]) (p<0.01). Among subjects with a CD4 cell count <200 cells/μL, the prevalence of M. perstans was 7-fold higher than that of L. loa (20.6% vs 2.9%)., Conclusions: This study suggests a similar exposure to L. loa infection of PLHIV and HIV-negative patients while M. perstans is more frequently found in HIV-positive individuals, notably those with a CD4 count <200 cells/μL., (© The Author(s) 2022. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene.)

Background: Patients with acute febrile illness need to be screened for malaria and coronavirus disease 2019 (COVID-19) in malaria-endemic areas to reduce malaria mortality rates and to prevent the transmission of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)., Objectives: To estimate the frequency of children and adolescents with COVID-19 and/or malaria among febrile patients attending for malaria diagnosis., Method: This cross-sectional study was conducted in a sentinel site for malaria surveillance during the SARS-CoV-2 pandemic (Omicron variant), from October 2021 to December 2021 in Gabon. All febrile patients were tested for malaria using microscopy. Severe acute respiratory syndrome coronavirus 2 was detected by real time polymerase chain reaction (RT-PCR) and rapid antigen tests developed by Sansure Biotech ® ., Results: A total of 135 patients were screened. Their median age was 6 (interquartile range [IQR]: 3-14) years. Malaria was confirmed for 49 (36.3%) patients, 29 (32.5%) children, 13 (59.0%) adolescents and 7 (29.2%) adults. The frequency of COVID-19 cases was 7.4% ( n = 10/135), and it was comparable between children ( n = 6; 6.7%), adolescents ( n = 2; 9.1%) and adults ( n = 2; 8.3%) ( p = 0.17). Malaria and COVID-19 co-infections were diagnosed in 3 (6.1%) patients from all the age groups. Participants with a co-infection had a higher median temperature, a higher median parasitaemia, and were mostly infected with non- falciparum malaria., Conclusion: COVID-19 cases and cases of malaria/COVID-19 co-infections were found in febrile children and adolescents. SARS-CoV-2 testing should be included in the screening of suspected malaria cases., Contribution: This study highlights the presence of malaria-COVID-19 coinfection among children and adolescents who should also be screened for both diseases, like for adults., Competing Interests: The authors declare that they have no financial or personal relationships that may have inappropriately influenced them in writing this article., (© 2022. The Authors.)

Malaria, blood-borne filarial worms and intestinal parasites are all endemic in Gabon. This geographical co-distribution leads to polyparasitism and, consequently, the possibility of immune-mediated interactions among different parasite species. Intestinal protozoa and helminths could modulate antimalarial immunity, for example, thereby potentially increasing or reducing susceptibility to malaria. The aim of the study was to compare the cytokine levels and cytokine ratios according to parasitic profiles of the population to determine the potential role of co-endemic parasites in the malaria susceptibility of populations. Blood and stool samples were collected during cross-sectional surveys in five provinces of Gabon. Parasitological diagnosis was performed to detect plasmodial parasites, Loa loa, Mansonella perstans, intestinal helminths (STHs) and protozoan parasites. Nested PCR was used to detect submicroscopic plasmodial infection in individuals with negative blood smears. A cytometric bead array was used to quantify interleukin (IL)-6, IL-10 and tumour necrosis factor (TNF)-α in the plasma of subjects with different parasitological profiles. Median IL-6 and IL-10 levels and the median IL-10/TNF-α ratio were all significantly higher among individuals with Plasmodium (P.) falciparum infection than among other participants (p<0.0001). The median TNF-α level and IL-10/IL-6 ratio were higher in subjects with STHs (p = 0.09) and P. falciparum-intestinal protozoa co-infection (p = 0.04), respectively. IL-6 (r = -0.37; P<0.01) and IL-10 (r = -0.37; P<0.01) levels and the IL-10/TNF-α ratio (r = -0.36; P<0.01) correlated negatively with age. Among children under five years old, the IL-10/TNF-α and IL-10/IL-6 ratios were higher in those with intestinal protozoan infections than in uninfected children. The IL-10/TNF-α ratio was also higher in children aged 5-15 years and in adults harbouring blood-borne filariae than in their control counterparts, whereas the IL-10/IL-6 ratio was lower in those aged 5-15 years with filariae and intestinal parasites but higher in adults with intestinal parasitic infections. Asymptomatic malaria is associated with a strong polarization towards a regulatory immune response, presenting high circulating levels of IL-10. P. falciparum/intestinal protozoa co-infections were associated with an enhanced IL-10 response. Immunity against malaria could differ according to age and carriage of other parasites. Helminths and intestinal protozoa can play a role in the high susceptibility to malaria currently observed in some areas of Gabon, but further investigations are necessary., Competing Interests: The authors have declared that no competing interests exist.

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: Msp1 gene 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., Competing Interests: Conflict of interest The authors declare none conflict of interest whatever the aspect financial and personal that could bias their work. They also declare that all the data presented in the manuscript are their own original work and they take complete responsibility for the integrity of the data and the accuracy of the data analysis., (Copyright © 2021 Mawili-Mboumba et al. Published by Tehran University of Medical Sciences.)

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 < 70 years, from six African countries and Vietnam. Patients were followed up for 63 days to assess treatment efficacy, safety and pharmacokinetics. The primary efficacy endpoint was the polymerase chain reaction (PCR)-adjusted adequate clinical and parasitological response (ACPR) at Day 28 in the Per-Protocol [PP] Set comprising only African patients ≤ 5 years. The exposure-response relationship for PCR-adjusted ACPR at Day 28 and prevalence of 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.

Introduction: Intestinal parasites infections are endemic in Gabon. Nevertheless, they are rarely described in people living with HIV (PLHIV)., Objective: The frequency of intestinal parasite infection was estimated and compared between HIV-positive and HIV uninfected individuals in Gabon; factors associated with intestinal parasites were also analysed., Material and Methods: Using a cross-sectional study design sociodemographic data, life style habits, antiretroviral therapy, cotrimoxazole use and CD4 cell count were recorded.. Stool samples from participants living in Koulamoutou and Oyem were analysed using microscopy. Chi-squared or fisher's exact tests and logistic regression were performed., Results: Among participants (n=332), female gender was predominant (73.7%; n=135/183) and the median age was 45 [33-57] years old. Among 183 samples, 53.6% (n = 98/183) were infected by intestinal parasites. The proportion was higher (72.1%) in HIV negative participants compared to PLHIV (42.6%) (p <0.01). PLHIV were more frequently poly-infected. Infection was frequent in patients using external toilets and tap water (>70.0%)., Conclusion: Prevalence of intestinal parasites is higher in seronegative participants but polyparasitism is more frequent in PLHIV. Strategies are focused on HIV negative population, but this study shows the importance of sensitization for PLHIV to improve their quality of life., (© 2020 Lengongo JVK et al.)

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., (© The Author(s) 2020. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene.)

Introduction: Rapid diagnostic tests (RDTs) are selected based on their performances. Here, we compared the diagnostic performance of different malaria RDTs., Methods: Febrile patients were tested for malaria using Vikia Malaria Pf/Pan, Meriline-Meriscreen Pf/Pv/Pan, Right Sign Malaria Pf/Pan, and Right Sign Malaria Pf RDTs at Melen Regional Hospital in Gabon., Results: In total, 120 of 274 tested children (43.8%) had malaria. The sensitivity was > 95% for all RDTs, while the specificity was > 85% for two tests. One test generated invalid tests (8%)., Conclusions: Based on their performances, all tests except one may be recommended for malaria diagnosis.

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.

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Background: Studying malaria parasites cross resistance to sulfadoxine-pyrimethamine (SP) and trimethoprim-sulfamethoxazole (cotrimoxazole, CTX) is necessary in areas coendemic for malaria and HIV. Polymorphism and frequency of drug resistance molecular markers, Pfdhfr and Pfdhps genes have been assessed in Plasmodium falciparum isolates from HIV-infected adults, in Gabon., Materiel and Methods: A cross-sectional study was conducted in three HIV care and treatment centers, at Libreville, the capital city of Gabon and at Oyem and Koulamoutou, two rural cities between March 2015 and June 2016. P. falciparum -infected HIV adults were selected. Analysis of Pfdhfr and Pfdhps genes was performed using high resolution melting (HRM) technique., Results: Pfdhps A581G mutation was found in 23.5% (8/34) of the isolates. Triple Pfdhfr mutation (51I-59R-108N) was predominant (29.4%; n=10) while 17.6% (n=6) of the isolates carried a quadruple mutation (Pfdhfr 51I-59R-108N + Pfdhps 437G; Pfdhfr 51I-108N + Pfdhps 437G- Pfdhps 581G; Pfdhfr 51I-59R-108N + Pfdhps 581G). Highly resistant genotype was detected in around 10% (n=3) of the isolates. The quintuple mutation (triple Pfdhfr 51I-59R-108N and double Pfdhps 437-581) was only found in isolates from two patients who did not use CTX. The most frequent haplotypes were those with a single mutation ( N CNIAKA) (36%) and a quadruple mutation ( N C I I G K G , NRI I G KA, and NRI IAK G ). Mixed unknown genotypes were found at codon 164 in three isolates. Mixed genotypes were more frequent at codons 51 (23.5%; n=8) and 59 (20.5%; n=7) ( p <0.01)., Conclusion: Pfdhps A581G mutation as well as new combination of quintuple mutations is found for the first time in isolates from HIV-infected patients in Gabon in comparison to a previous study. The detection of these genotypes at a nonnegligible frequency underlines the need of a regular surveillance of antifolates drug resistance.

Introduction: Knowledge of the infectious status of the Glossina is an indicator of risk of resurgence of Human African Trypanosomiasis (HAT). Environmental conditions have an impact on the density and diversity of both vector and Trypanosoma. The aim of the study was to determine the diversity and the infection rate of Glossina as well as the diversity of trypanosome species within habitats of an old HAT focus, in Gabon., Methodology: Glossina were captured in September 2012 in three ecological sites. Vavoua traps were installed for twelve days. All captured flies were identified. Glossina were selected for trypanosome identification by Polymerase Chain Reaction., Results: 1178 Glossina were captured: 55.8% in degraded forest, 28.9% in flood area and 15.4% in secondary forest. Glossina fusca congolensis (37%) and G.palpalis palpalis (36.4%) were the most abundant vector species. G. fusca congolensis was predominant in secondary forest and in flood area, while in degraded forest, it was G.palpalis palpalis. Trypanosoma infection rate was 30.7%, 42% in secondary forest, 32% in degraded forest and 18% in flood area. Trypanosoma congolense savannah was the main species detected (18.7%) followed by T.brucei brucei (10.7%) and T. brucei gambiense (4%). T. congolense savannah type was predominant in the secondary forest and in degraded forest (66.7% versus 55.5%)., Conclusion: Glossina density and trypanosome infection rate varied according to the habitat within HAT focus. The density of tsetse was the highest in degraded forest while the infection rate was highest in secondary forest. Continuous disease surveillance and control measures are needed., Competing Interests: No Conflict of Interest is declared, (Copyright (c) 2019 Ornella Mbang Nguema, Marielle Bouyou Akotet, Jacques Mavoungou, Denise Patricia Mawili Mboumba.)

The aim of this study was to assess the proportion of Pfcrt -76T mutant allele four years after the adoption of new malaria control guidelines in Gabon and Ivory Coast. Frequency of K76T mutation of Pfcrt gene was compared between Plasmodium falciparum isolates from Gabon and Ivory Coast. Samples were collected in 2008 in Gabon and in 2009 in Ivory Coast. In total, 151 isolates were selected and analysed by nested-PCR-RFLP for Pfcrt- 76 allele identification: 63 in Abobo (Ivory Coast) and 78 in Oyem (Gabon). The proportion of Pfcrt- 76T mutant allele was higher in Oyem (70%) compared to Abobo (46%) (p=0.005). This allele was more frequently detected in patients less than 5 years old in Oyem (75 %) compared to Abobo (52%) ( p <0.01). The present work showed different prevalence of Pfcrt -76T allele between both sites probably due to a different drug pressure on P. falciparum strains circulating in these areas. Moreover, a decrease of the mutation frequency is observed compared to data obtained in 2005. Therefore, a continuous monitoring of this allele and other drug resistance molecular markers is required in these countries., Competing Interests: The authors have no conflicts of interest to declare

Unfortunately, the original article [1] contained some errors. The table title of Tables 4, 5, 6, 7 were interchanged by mistake and displayed incorrectly in the article. The correct table titles of Tables 4, 5, 6, 7 can be found below.

Background: Submicroscopic malaria infections contribute to malaria transmission. Describing the extent of the parasite reservoir is of importance. In people living with human immunodeficiency virus (HIV), the frequency of subpatent malaria infections is rarely reported. The aim of the present study was to determine the frequency of submicroscopic infections in people living with HIV in Gabon and its relationship with cotrimoxazole (CTX) use., Methods: A survey was conducted in two health care centres in rural areas (Koulamoutou and Oyem) and three in urban areas (Libreville) of Gabon from March 2015 to June 2016. Blood samples were collected from consenting people living with HIV with a negative blood smear. Information on CTX and antiretroviral therapy intake was recorded from the medical file of the patient and through an interview. For molecular analysis, the Plasmodium small subunit ribosomal RNA gene was amplified by nested polymerase chain reaction., Results: Submicroscopic infections were detected in 10.1% (n=12/119) of the people living with HIV, more frequently in those residing in rural areas (15.1%) compared with urban areas (2.1%) (p<0.01). The proportion of anaemic patients was 1.74-fold more frequent in malaria-infected patients, although not statistically significant. Submicroscopic infections frequency did not vary according to CTX intake (p=0.6)., Conclusions: The present pilot study highlights a non-negligible frequency of submicroscopic malaria infections in people living with HIV from rural areas, but no relationship with CTX intake was found.

Objective : This study determined the prevalence of asymptomatic Plasmodium (P.) falciparum infection and anemia in adults living with HIV/AIDS (PLHIV) and compared malaria prevalence between 858 HIV-infected (PLHIV) and 272 uninfected individuals in Gabon where such information are lacking. Factors influencing malaria and anemia were also investigated., Patients and Methods: Participants were screened for malaria. Available hemoglobin level, socio-demographic and use of prevention or treatment data were compared between both groups., Results: The prevalence of asymptomatic parasitemia was 13.5%, lower in PLHIV (7.1%) than uninfected individuals (33.8%) (p<0.01). Among the PLHIV, females (p<0.01), those aged below 25 years old (p=0.03), those with primary education (p=0.03) and those with a CD4 cell count below 200/mm3 (p=0.03) had a higher median parasitemia. Cotrimoxazole use was associated with a lower prevalence of malaria (p<0.01). Age below 25 years was independently associated with malaria in PLHIV (p<0.01). Anemia prevalence was 42.1% among the PLHIV, higher in the youngest and those with low CD4 cell count (p<0.01). P.falciparum-infected PLHIV aged below 25 years old, not under ART, with low CD4 cell count and under cotrimoxazole had the lowest median hemoglobin level., Conclusion: The prevalence of asymptomatic malaria is low among the PLHIV while the burden of anemia is considerable. Age below 25 years and CD4 cell count are associated factors. The cotrimoxazole use reduces the frequency of malaria.

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 (p<0.01) 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 (p<0.01) and Mad20 (p<0.01) 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., (Copyright © 2017 Elsevier B.V. All rights reserved.)

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 < 0.01). The polyparasitism rate was 41.5%, with 7.0% Plasmodium-IPIs and 1.8% Plasmodium-STH co-infections. The multivariate analysis showed that living in a suburban area, belonging to the age group of 5-15 years, having none or a secondary education, or having an open body water close to home were significant risk factors for malaria (P ≤ 0.01). For STH infections, identified risk factors were drinking untreated water and living in a rural area (P ≤ 0.04). No significant predictors were identified for IPIs and malaria-IPI co-infection., Conclusions: This study reports a high prevalence of IPIs and intestinal protozoa, but a low rate of malaria-IPI co-infections in the study sites. Improvements in the living conditions of the population such as adequate water supply and proper health education and sanitation should be integrated into control strategies for malaria, STHs, and IPIs.

AbstractCharacterization of the parasite reservoir is required to improve malaria control. Asymptomatic patients with subpatent parasitemia have been identified in Gabon, but the prevalence of such infections among febrile subjects is unclear. We assessed the prevalence of submicroscopic Plasmodium falciparum infections on an island (Port-Gentil), and in urban (Libreville), semiurban (Melen), and rural (Oyem) settings in Gabon. Blood samples ( N = 310) from febrile patients were tested for malaria parasites by quantitative nucleic acid sequence-based amplification (QT-NASBA). Parasites were detected in 55.8% (173/310) of samples by microscopy and in 66.4% (206/310) of samples by 18S rRNA QT-NASBA. The proportion of submicroscopic infections differed considerably between sites. Gametocytes were found in 1% (3/310) of the individuals by microscopy and in 32% (99/310) by Pfs25 mRNA QT-NASBA. Thus, submicroscopic parasitemia is frequent in febrile patients, and the detection of this condition is important, to improve disease control.

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.

The relationship between the frequency of loiasis objective symptoms and microfilaraemic or amicrofilaraemic infection was assessed in 1148 exposed patients also infected, or not, with Mansonella perstans. Filarial infections were detected by direct microscopy, leucoconcentration and serology, with prevalence values of 39.5% Loa loa, 5.6% M. perstans and 3.4% co-infection with both filarial species. Amicrofilaraemic or occult loiasis (OL) predominated among L. loa-infected individuals, with a prevalence of 58.2%. Hypermicrofilaraemia (>8000 microfilariae (mf)/ml) was found in 18.4% of L. loa microfilaraemic patients, with 25.7% of them harbouring more than 30,000 mf/ml. Up to 34% of patients with OL showed evidence of Calabar swelling, compared with 26.3% of microfilaraemic patients (P= 0.03). Overall 5.3% of patients presented with adult worm migration across the eye, representing 16.3% of microfilaraemic individuals and 11.4% of amicrofilaraemic patients (P= 0.13). This symptom was similarly found in patients with more than 30,000 mf/ml (22%), those with microfilaraemia between 8 and 30,000 mf/ml (15.4%) and also in individuals with low or without microfilaraemia (16.1%) (P= 0.7). Five (14.3%) hypermicrofilaraemic patients did not present any L. loa-specific objective symptoms, as well as all the patients with single M. perstans infection. The presence of adult eye worm migration as a strong predictor of high microfilaraemia density would obscure the real burden of L. loa hypermicrofilaraemia in exposed individuals. For epidemiological purposes and control strategies, the mapping of L. loa in endemic areas should also take into account the group of patients with occult loiasis.

Human African trypanosomiasis became a neglected disease after the 1960s, when case numbers dropped dramatically. It again became a public health problem in sub-Saharan Africa at the end of the 1990s, when new cases were reported, notably in Central Africa, and specifically in Gabon, where historic foci existed and new cases have been reported. Therefore, the present study reports on an entomological survey conducted in May 2012 to determine the pathogenic trypanosome infection rate in tsetse flies and characterize the diversity of Trypanosoma species in the Ivindo National Park (INP) in northeastern Gabon. Nine Vavoua traps were used to catch tsetse over a 7-days period. All tsetse flies captured were identified to species, dissected, and trypanosome species identified using polymerase chain reaction (PCR). In total, 160 tsetse flies were analyzed, including Glossina palpalis palpalis, Glossina fusca congolense, and Glossina tachinoïdes The trypanosome infection rate of the flies was 6.3 and 31.9% using microscopy and PCR, respectively. The species identified were Trypanosoma congolense savannah type, Trypanosoma brucei brucei, Trypanosoma brucei gambiense, Trypanosoma vivax, and Trypanosoma congolense forest type. Trypanosoma risk index was 0.75 and 7.05 for humans and for animals, respectively. This study illustrates the diversity of Trypanosoma species infecting the tsetse flies in the INP. The simultaneous occurrence of Trypanosoma and tsetse from the palpalis group may suggest that the reservoirs of African animal trypanosomiasis should be carefully monitored in this area., (© The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

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<0.01). Birth weight significantly rose with increasing age (p<0.01), parity (p=0.03) and number of SP doses (p=0.03). A birth weight reduction of 230 g in case of peripheral parasitaemia (p=0.02) and of 210 g with placental parasitaemia (p=0.13) was observed., Conclusions: Microscopic P. falciparum prevalence during pregnancy significantly declined between 2005 and 2011, following IPTp-SP implementation in Gabon. Young women and paucigravidae remain the most susceptible to malaria and associated outcomes., (© The Author 2016. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

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 ≤ 7 g/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 Gabon, sulfadoxine-pyrimethamine (SP) is recommended for intermittent preventive treatment during pregnancy (IPTp-SP) and for uncomplicated malaria treatment through ACTs drug. P. falciparum strains resistant to SP are frequent in areas where this drug is highly used and is associated with the occurrence of mutations on Plasmodium falciparum dihydrofolate reductase (Pfdhfr) and dihydropteroate synthetase (Pfdhps) genes. The aim of the study was to compare the proportion of mutations on Pfdhfr and Pfdhps genes in isolates collected at Oyem in northern Gabon, in 2005 at the time of IPTp-SP introduction and three years later. Point mutations were analyzed by nested PCR-RFLP method. Among 91 isolates, more than 90% carried Pfdhfr 108N and Pfdhfr 59R alleles. Frequencies of Pfdhfr 51I (98%) and Pfdhps 437G (67.7%) mutant alleles were higher in 2008. Mutations at codons 164, 540, and 581 were not detected. The proportion of the triple Pfdhfr mutation and quadruple mutation including A437G was high: 91.9% in 2008 and 64.8% in 2008, respectively. The present study highlights an elevated frequency of Pfdhfr and Pfdhps mutant alleles, although quintuple mutations were not found in north Gabon. These data suggest the need of a continuous monitoring of SP resistance in Gabon.

Introduction. The characterization of genetic profile of Plasmodium isolates from different areas could help in better strategies for malaria elimination. This study aimed to compare P. falciparum diversity in two African countries. Methods. Isolates collected from 100 and 73 falciparum malaria infections in sites of Côte d'Ivoire (West Africa) and Gabon (Central Africa), respectively, were analyzed by a nested PCR amplification of msp1 and msp2 genes. Results. The K1 allelic family was widespread in Côte d'Ivoire (64.6%) and in Gabon (56.6%). For msp2, the 3D7 alleles were more prevalent (>70% in both countries) compared to FC27 alleles. In Côte d'Ivoire, the frequencies of multiple infections with msp1 (45.1%) and msp2 (40.3%) were higher than those found for isolates from Gabon, that is, 30.2% with msp1 and 31.4% with msp2. The overall complexity of infection was 1.66 (SD = 0.79) in Côte d'Ivoire and 1.58 (SD = 0.83) in Gabon. It decreased with age in Côte d'Ivoire in contrast to Gabon. Conclusion. Differences observed in some allelic families and in complexity profile may suggest an impact of epidemiological facies as well as immunological response on genetic variability of P. falciparum.

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.

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<0.01). Mutations I164L and A581G were not found, while higher proportions of 436 and 437 mutations were detected in 2011.A trend toward a higher frequency of isolates with five mutations was observed in women who received two SP doses (p<0.01). Pfs25mRNA was found in 6.8 % (n = 3/44) and 34.6% (n = 27/78) of the samples collected in 2005 and 2011 respectively (p<0.01). In 2011, 74.0% (n = 20/27) of women with detected submicroscopic gametocytes carried parasites with the S108N/C59R/N51/S436A/A437G multiple mutation. All the ten delivering women who received three IPTp-SP doses had a submicroscopic Plasmodium falciparum infection, but none had detected gametocytes. Following IPTp-SP implementation, an increase in the frequency of multiple mutant parasites and of submicroscopic gametocyte carriage was observed among pregnant women living in Gabon.

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., (© M.K. Bouyou-Akotet et al., published by EDP Sciences, 2015.)

Background: Studies showed that chloroquine resistance may revert to sensitivity after its withdrawal mainly detected by a significant decrease of Plasmodium falciparum pfcrt 76T and pfmdr1 86Y alleles. Besides, self-medication is considered as a key factor of antimalarial drug resistance expansion. Thus, pfcrt 76T and pfmdr1 86Y allele frequency and its relationship with antimalarial drug self-medication was analyzed in P. falciparum isolates collected in Gabon., Methods: Samples were collected from febrile children screened for P. falciparum infection in 2005 and 2008 at the regional hospital of Oyem. Self-use of antimalarial drugs before the day of consultation was recorded. Polymorphic codons 76 and 86 of pfcrt and pfmdr1 genes were analyzed by PCR-RFLP., Results: The frequency of pfcrt 76T mutant allele was greater than 70.0% in 2005 and 2008. Wild type isolates were 1.7-fold more prevalent in 2008. The prevalence of pfmdr1 86Y mutant allele was comparable between 2005 and 2008 (p=0.1); the proportion of wild type allele reached 20.5% in 2008. The frequency of wild type allele pfcrt K76 or pfmdr1 N86 was higher among patients without anti-malarial drug self-medication compared to those who used it., Conclusions: An increase of the frequency of P. falciparum wild type allele pfcrt 76K and pfmdr1 86N was observed within a short period after chloroquine withdrawal. The proportion of mutant genotypes is still high, mainly among patients using self-medication with antimalarial drugs., (© The Author 2014. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The aim of the study was to re-assess the treatment outcomes of Gabonese children, treated with sulfadoxine-pyrimethamine (SP) and artesunate-mefloquine (AM) and categorized by microscopy as adequate clinical and parasitological response (ACPR), using polymerase chain reaction (PCR). Dried blood spots were collected at day 0 and day 28 and stevor gene amplification was performed to detect Plasmodium falciparum infections. Plasmodial DNA was found in 27.5% (n=19/69) of the isolates collected at day 28; this proportion was 34.3% (n=12/35) in the SP group and 20.6% (n=7/34) in the AM group. This study underlines the need of an accurate and more appropriate technique such as PCR to evaluate antimalarial drug efficacy during clinical trials., (Copyright © 2014 Elsevier B.V. All rights reserved.)

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.

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). falciparum was 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 of P. falciparum infection. 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 with P. falciparum microscopic and submicroscopic asymptomatic infection or clinical malaria should be emphasized to reduce the transmission.

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.

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.

The Malaria Pf Rapid Test Device Acon® (Acon Labs) and the pan HRP2/aldolase RDT, Malaria P.f/Pan Rapid Test Device Acon® (Acon Labs), performances were evaluated for malaria species diagnosis in 592 febrile patients living in Gabon using microscopy as gold standard. Sensitivities were equal or above 96.0% for Plasmodium falciparum detection, of 62.5% for non-P. falciparum malaria species detection and higher in younger children (100%). Negative predictive values were greater than 97.0%. Acon®HRP2 had a higher specificity (96.6%) and lower false-positive (FP) rate (9.3%) compared to Acon®Pf/Pan, which had a specificity of 87.3% and a FP rate of 27.1% (P < 0.01). Overall, 32.5% of all Acon® Pf/Pan tests resulted in a "faint band" with only 2 resulted from samples with a parasitemia below 100 p/μL. The accuracy of Acon®HRP2 RDT for the diagnosis of P. falciparum infection is confirmed. However, the high FP rate observed with Acon®Pf/Pan is a limitation for its use., (Copyright © 2013 Elsevier Inc. All rights reserved.)

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: Following the deployment of new recommendations for malaria control according to the World Health Organization, an estimation of the real burden of the disease is needed to better identify populations at risk and to adapt control strategies. The aim of the present study was to estimate the clinical burden of malaria among febrile children aged less than 11 years, before and after six-year of deployment of malaria control strategies in different areas of Gabon., Methods: Cross-sectional surveys were carried out in health care facilities at four locations: two urban areas (Libreville and Port-Gentil), one semi-urban area (Melen) and one rural area (Oyem), between 2005 and 2011. Febrile paediatric patients, aged less than 11 years old were screened for malaria using microscopy. Body temperature, history of fever, age, sex, and location were collected., Results: A total of 16,831 febrile children were enrolled; 78.5% (n=13,212) were less than five years old. The rate of Plasmodium falciparum-infection was the lowest in Port-gentil (below 10%) and the highest at Oyem (above 35%). Between 2005 and 2008, malaria prevalence dropped significantly from 31.2% to 18.3%, followed by an increase in 2011 in Libreville (24.1%), Port-Gentil (6.5%) and Oyem (44.2%) (p<0.01). Median age among the infected patients increased throughout the study period reaching 84 (60-108) months in Libreville in 2011 (p<0.01). From 2008, at all sites, children older than five years were more frequently infected; the risk of being infected significantly increased with time, ranging from 0.37 to 1.50 in 2005 and from 2.03 to 5.10 in 2011 in this group (p<0.01). The risk of being P. falciparum-infected in children aged less than five years old significantly decreased from 2008 to 2011 (p<0.01)., Conclusions: This study shows an increased risk of malaria infection in different areas of Gabon with over-five year-old children tending to become the most at-risk population, suggesting a changing epidemiology. Moreover, the heterogeneity of the malaria burden in the country highlights the importance of maintaining various malaria control strategies and redefining their implementation.

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.