Randomized, open-label, phase 2a study to evaluate the contribution of artefenomel to the clinical and parasiticidal activity of artefenomel plus ferroquine in African patients with uncomplicated Plasmodium falciparum malaria.

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 AUC0-∞ to Day 28 PCR-adjusted ACPR was not demonstrated when accounting for ferroquine AUC0-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).

Allelic Diversity of MSP1 Gene in Plasmodium falciparum from Rural and Urban Areas of Gabon.

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.

Low diagnostic performance of thick blood smears of 50 µl in comparison with direct examination of 10 µl blood and the leukoconcentration technique of 5ml blood among loiasis-suspected patients with low microfilaremia in Gabon, Central Africa, using the STARD-BLCM guidelines.

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.

Prevalence of cardiometabolic risk factors according to urbanization level, gender and age, in apparently healthy adults living in Gabon, Central Africa.

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.

C-reactive protein and high-sensitivity C-reactive protein levels in asymptomatic intestinal parasite carriers from urban and rural areas of Gabon.

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.

Sub-microscopic gametocyte carriage in febrile children living in different areas of Gabon.

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.

Antenatal care visit attendance, intermittent preventive treatment and bed net use during pregnancy in Gabon.

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.

Sociodemographics, Clinical Factors, and Biological Factors Associated with Loiasis in Endemic Onchocerciasis Areas in Southern Gabon.

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.

Drug Resistance Molecular Markers of Plasmodium falciparum and Severity of Malaria in Febrile Children in the Sentinel Site for Malaria Surveillance of Melen in Gabon: Additional Data from the Plasmodium Diversity Network African Network.

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.

Evolution and spread of Plasmodium falciparum mutations associated with resistance to sulfadoxine-pyrimethamine in central Africa: a cross-sectional study.

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.

Complicated malaria and other severe febrile illness in a pediatric ward in Libreville, Gabon.

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.

Circulating IL-6, IL-10, and TNF-alpha and IL-10/IL-6 and IL-10/TNF-alpha ratio profiles of polyparasitized individuals in rural and urban areas of gabon.

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.

[Parental administration of unprescribed antimalarial drugs to treat febrile children in Gabon]. / Usage des antipaludiques en automédication pour le traitement de la fièvre chez les enfants au Gabon.

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.

[Trends in the prevalence of malaria and anemia at delivery in Libreville from 1995 to 2011]. / Infection plasmodiale et anémie chez des parturientes du Centre hospitalier de Libreville entre 1995 et 2011.

In 1995, 2005 and 2011, cross-sectional studies of 611 parturients at the Centre Hospitalier de Libreville in Gabon assessed the prevalence of maternal malaria and anaemia; two indicators of poor pregnancy outcomes. The prevalence of Plasmodium falciparum infection in maternal peripheral blood decreased from 25% in 2005 to 6% in 2011. Parasite density was significantly lower in 2005 (31 p/µL) than in 1995 (1,240 p/µL) or 2011 (35,055 p/µL). Anaemia prevalence was high (>50%) in 1995 and in 2005, but fell by more than 50% (24%) in 2011. After implementation of new malaria prevention strategies during pregnancy, the prevalence of both maternal peripheral P. falciparum infection and anaemia fell. Studies are necessary to assess the efficacy of these strategies and to seek other causes of anaemia.

Plasmodium falciparum Allelic Diversity: A Comparison of DNA Extraction from Isolates Collected on Rapid Diagnostic Tests (Rdts) and Filter Paper.

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.

High prevalence of sulfadoxine/pyrimethamine-resistant alleles of Plasmodium falciparum isolates in pregnant women at the time of introduction of intermittent preventive treatment with sulfadoxine/pyrimethamine in Gabon.

OBJECTIVES: The frequency of dhfr and dhps point mutations was assessed in Plasmodium falciparum isolates from pregnant women in Libreville. METHODS: 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. RESULTS: 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 was >90% for both genes. CONCLUSIONS: 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.

Prevalence and associated factors of intestinal parasite infection by HIV infection status among asymptomatic adults in rural Gabon.

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.

Comparative performance of four malaria rapid diagnostic tests, Vikia Malaria Pf/Pan, Meriline-Meriscreen Pf/Pv/Pan, Right Sign Malaria Pf/Pan, and Right Sign Malaria Pf, among febrile patients in Gabon.

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.

Evidence of decline of malaria in the general hospital of Libreville, Gabon from 2000 to 2008.

BACKGROUND: Substantial decline in malaria transmission, morbidity and mortality has been reported in several countries where new malaria control strategies have been implemented. In Gabon, the national malaria policy changed in 2003, according to the WHO recommendations. The trend in malaria morbidity was evaluated among febrile children before and after their implementation in Libreville, the capital city of Gabon. METHODS: From August 2000 to December 2008, febrile paediatric outpatients and inpatients, under 11 years of age, were screened for malaria by microscopic examination at the Malaria Clinical Research Unit (MCRU) located in the largest public hospital in Gabon. Climatic data were also collected. RESULTS: In total, 28,092 febrile children were examined; those under five years always represented more than 70%. The proportion of malaria-positive slides was 45% in 2000, and declined to 15% in 2008. The median age of children with a positive blood smear increased from 24(15-48) to 41(21-72) months over the study period (p < 0.01). Rainfall patterns had no impact on the decline observed throughout the study period. CONCLUSION: The decrease of malaria prevalence among febrile children during the last nine years is observed following the introduction of new strategies of malaria cases management, and may announce epidemiological changes. Moreover, preventive measures must be extended to children older than five years.

Variations of Glossina sp. and trypanosome species frequency within different habitats in a sleeping sickness focus, Gabon.

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.