Southeastern Gabon Research Articles

High prevalence of asymptomatic Anaplasma spp. infection in school-aged children in southeastern Gabon

ObjectivesThe objective of this study was to evaluate the detection rates of asymptomatic Anaplasma spp. and Ehrlichia spp. infections in children in southeastern Gabon. MethodsWe conducted a cross-sectional study among school-aged children in southeastern Gabon between May and June 2021. Blood samples were collected. Anaplasmataceae, Anaplasma spp., and Ehrlichia spp. were detected by microscopy and polymerase chain reaction. ResultsOf the 452 blood samples collected, 57.5% (n/N=260/452) of the samples were positive for Anaplasma spp. and/or Ehrlichia spp. by microscopy, 86.9% (n/N=393/452) of the samples were positive for both Anaplasmataceae and Anaplasma spp., and none of the samples were found positive for Ehrlichia spp. PCR was more sensitive and specific than microscopy for detection of Anaplasma spp.. ConclusionsIn our study, a significant number of positive blood samples for Anaplasma spp. were found in school-aged children in southeastern Gabon. Further studies are needed to determine the prevalence of different species of Anaplasma, their pathogenicity, and their transmission patterns.

Ethnopharmacological Survey, Phytochemical Screening and Antimicrobial Activities of Medicinal Plants Used in the Treatment of Diarrhea in Southeastern Gabon.

Diarrhea is a condition that particularly affects children under five the age of years old in developing countries. The aim of this study was to evaluate the efficacy of medicinal extracts plants used in treatment and to characterize their inhibitory capacity in the growth of bacteria isolates in childhood diarrhea in the southeast region of Gabon. An ethnobotanical survey on the plants used in the treatment of diarrhea in southeastern Gabon was carried out and a phytochemical screening of the collected plants was performed. The antimicrobial activity of aqueous extracts was evaluated; 33 plant species were identified, representing 28 genera and 19 families. Bark (39.5%) was the most commonly used plant part, followed by powder formulations (28.9%). The preferred method of preparation and chewing (44.7%), together with drinking (36.8%), were the most prevalent modes of administration. Phytochemical screening showed a plethora of secondary metabolites (terpenoids, alkaloids and phenolic compounds), and a marked level of anti-diarrheal activity was found with Sida acuta and Santiria. ebo against Shigella spp. (16.22 ± 0.7 mm and 14.05 ± 1.4 mm) and Yersinia pestis (16.35 ± 0.5 mm and 15.51 ± 0.5 mm). The high diversity of secondary plant metabolites and their inhibitory ability against enteric pathogens would justify their use at the local level to treat diarrheal infections.

Carrying Asymptomatic Malaria In Ouéllé Locality, And Surrounding Villages, In Southeastern Gabon: An Epidemiological Analysis, In Rural Central Africa

Background: Malaria remains a major public health problem in sub-Saharan Africa, and particularly in Gabon. In an epidemiological analysis in a rural area, the present study assessed asymptomatic malaria carriage in Ouéllé, and surrounding villages, in South-eastern Gabon: an epidemiological analysis, in a rural area of central Africa. Patients and method: This prospective, cross-sectional study was conducted from June 26 to 28, 2023. The sociodemographic characteristics of the participants were obtained. A small portion of blood collected by finger prick from each participant was used for qualitative detection of malaria-causing Plasmodium infection, using a Malaria Test MeriScreenTM Pf/PAN Ag lateral flow immunochromatographic assay. Results of analysis by R software version 4.0.3, were considered significant at p≤0.05.Results: Of the 321 people registered for the present study, 97 (30.22%) (95% CI: 0.25 - 0.36) (n=97), tested positive for malaria, compared with 224 (69.78%) ((95% CI: 0.64 - 0.75) (n=224). While a univariate analysis of the prevalence of malaria carriage according to gender showed no statistically significant association between the variables p=0.56, a univariate analysis of the prevalence of malaria carriage according to age group indicated that only participants aged between 28 and 57 (OR =0.17; 95% CI: [0.04 - 0.73] p=0. 007*), and according to each locality, the analysis showed that participants from Mvengué (OR =0.17; CI 95% : [0.04 - 0.73] p=0.007*), Djoutou (OR =0.17; CI 95% : [0.04 - 0.73] p=0. 007*), and Mouyabi (OR =0.17; 95% CI: [0.04 - 0.73] p=0.007*), were statistically susceptible to malaria were significantly associated with malaria carriage in the present study.Conclusion: These results, which indicate the persistence of asymptomatic malaria in Ouéllé and surrounding villages, call on Gabon's health authorities to redouble their efforts to combat malaria throughout the country.

Morphometric variability of Praomys misonnei (Rodentia: Muridae) in west central African forests reveals complex relationships between populations

This study addresses the morphological biometrics of Praomys misonnei and the signatures of its population history through a survey of external morphological characters measured on 133 individuals from eight West Central African (Gabon and Cameroon) localities. Four standard external characters were measured: head + body length, tail length, hindfoot length, and ear length. Using univariate and multivariate statistics, we inferred inter-population relationships from these morphometric characteristics and tested hypotheses of historical patterns of local adaptation (phylogenetic relationships) or of association with ecological gradients. We also tested the influence of sex on morphometric parameters. Our results support the existence of two morphometrically distinct groups of P. misonnei. The first one includes individuals from northern, central, and southern Gabon, while the second one includes individuals from southern Cameroon and one locality in southern Gabon (Mbaya). This result could be explained by the fact that the first group inhabits an area mainly covered by dense rainforest (about 90% of Gabon), while the second group is found in degraded forest or mosaics of forest-savanna habitats (Cameroon and southeastern Gabon). Another reason could be seasonal reversal, which has been postulated right at border between Gabon and Cameroon. The pattern of morphometric variation was correlated with local environmental factors. No sexual dimorphism was recorded.

Knowledge, attitudes, and practices of mothers regarding childhood malaria in southeastern Gabon

BackgroundIn Gabon, children under 5 years of age and pregnant women are the populations who are most at risk of malaria. Despite the presence of accessible health facilities, the community-based management of childhood fever remains a very common practice in Gabon, which may have serious consequences on child health. As such, the objective of this descriptive cross-sectional survey is to assess the mothers’ perception and knowledge of malaria and its severity.MethodsDifferent households were selected using the simple random sampling method.ResultsA total of 146 mothers from different households were interviewed in the city of Franceville, in southern Gabon. Among the households interviewed, 75.3% had a low monthly income (below the minimum monthly income of $272.73). Among the respondents, 98.6% of mothers had heard of malaria and 55.5% had heard of severe malaria. Regarding preventive measures, 83.6% of mothers used an insecticide-treated net as a means of protection. Self-medication was practiced by 68.5% of women (100/146).DiscussionThe use of health facilities was motivated by better care, the decision of the head of the family, but above all by the severity of the disease. Women identified fever as the main symptom of malaria, which could be beneficial for a quicker and more efficient management of the disease in children. Malaria educational campaigns should also increase awareness of severe forms of malaria and its manifestations. This study shows that Gabonese mothers react quickly when their children have fever. However, several external factors lead them to practice self-medication as a first resort. In this survey population, the practice of self-medication did not depend on social status, marital status, level of education, on the young age or inexperience of mothers (p > 0.05).ConclusionsThe data revealed that mothers may underestimate severe malaria and delay medical care by self-medicating, which can have detrimental effects for children and hinder the regression of the disease.

A search for life in Palaeoproterozoic marine sediments using Zn isotopes and geochemistry

Sediments from the 2.1- to 1.9-billion-year-old Francevillian Group in southeastern Gabon include centimeter-sized pyritized structures suggestive of colonial organisms (El Albani et al., 2010), some of which may have been motile (El Albani et al., 2019). However, these interpretations were largely based on morphological and geochemical characteristics that lack metabolic clues and/or can be explained by abiotic processes. To move this work forward, we describe other centimeter-sized specimens, loosely referred to as lenticular forms (LF), from the same area and apply a more holistic approach including morphology, mineralogy, and geochemistry. The objects are 0.2–4 cm in diameter, and most of them are endowed with a regular brim that scales proportionally to external diameter reminiscent of biological order, hence rendering the LF putative biogenic traces. The LF are perfectly delineated in every direction and deflect the sedimentary layers on which they rest. X-ray microtomography further demonstrates that the LF are syn-depositional features and not concretions, while lead isotope systematics indicate that the geochemical imprint of diagenesis is inconsequential. Low sulfur content is largely concentrated in the organic matrix, and scarcity of pyrite and its persistence as micron-sized crystals show that the role of sulfate reduction is minor. Most interestingly, the fillings of the LF cavities show large and correlated excesses of organic carbon and zinc, with the latter being distinctly enriched in its light isotopes. The geochemical anomalies of the fillings relative to the host rock, notably those associated with Zn, clearly were buried with the LF, and further imply biogenicity. In this regard, a ten-fold increase in LF size towards the top of the black shale series hosting the LF might be related to increasing Zn (nutrient) availability. Although we cannot conclude with any certainty what these remnant organisms were, their features all taken together are evocative of very large agglutinate protists that grazed on bacterial biomass either in the water column or as benthic mats.

Severe malaria in children and adolescents in Southeast Gabon

IntroductionMalaria remains a significant public health problem in sub-Saharan Africa. Child mortality due to severe malaria remains high in developing countries despite improvements in malaria management and a better understanding of its pathophysiology. To address the lack of epidemiological studies on severe malaria in Gabon, this study describes the epidemiological aspects of severe malaria in rural, semi-rural, and urban areas of southeast Gabon.MethodsDemographic, clinical, and laboratory data for children and adolescents aged 0–18 years were collected in 2019 from hospital records at three health facilities in southeastern Gabon. The patients included in the study were positive for P falciparum malaria diagnosed by microscopy with at least one of the malaria severity criteria.ResultsSevere malaria accounted for 18.8% (667/3552) of malaria cases. Children aged 0–5 years accounted for 71.8% (479/667) of all severe malaria cases. Adolescents over 15 years of age were the least affected by severe malaria with 4.2% (28/667). Across the study, severe anemia (49.0%, 327/667), convulsions (43.0%, 287/667), respiratory distress (5.1%, 34/667), and altered consciousness (4.8%, 32/667) were the most frequent clinical signs of severe malaria in children. Franceville was the locality most affected by severe malaria with 49.2% (328/667), followed by Koulamoutou with 42.0% (280/667) and Lastourville with 8.8% (59/667). Convulsions (50.6%, 166/328) and coma (6.1%, 20/328) were more frequent in children living in urban areas. In contrast, severe anemia (56.7%, 186/339) and jaundice (6.8%, 23/339) were more common in children living in semi-rural areas.ConclusionSevere malaria is more prevalent in urban areas in regions with a high malaria transmission intensity. However, in this study, the epidemiological characteristics of severe malaria were similar in the three settings (urban, rural, and semi-rural areas) despite different levels of urbanization. Nevertheless, the various signs of severity were more frequent in Franceville, an urban area. Children under 5 years of age remain the most vulnerable age group.

Molecular Prevalence of Diarrheal Pathogens in Children with Acute Diarrhea in Southeastern Gabon.

Diarrheal diseases are a major cause of morbidity and mortality in infants and young children, particularly in sub-Saharan countries. In Gabon, there are few data on the prevalence of diarrheal pathogens in children. The aim of this study was to assess the prevalence of diarrheal pathogens in children with diarrhea in southeastern Gabon. Stool samples (n = 284) from Gabonese children 0 to 15 years of age with acute diarrhea were analyzed using polymerase chain reaction targeting 17 diarrheal pathogens. At least one pathogen was detected in 75.7% of samples (n = 215). Coinfection with multiple pathogens was observed in 44.7% of patients (n = 127). Diarrheagenic Escherichia coli was the most commonly detected pathogen (30.6%, n = 87), followed by adenovirus (26.4%, n = 75), rotavirus (16.9%, n = 48), Shigella sp. (16.5%, n = 47), Giardia duodenalis (14.4%, n = 41), norovirus GII (7.0%, n = 20), sapovirus (5.6%, n = 16), Salmonella enterica (4.9%, n = 14), astrovirus (4.6%, n = 13), Campylobacter jejuni/coli (4.6%, n = 13), bocavirus (2.8%, n = 8), and norovirus GI (2.8%, n = 8). Our study provides useful information on the possible causes of diarrheal diseases affecting children in southeastern Gabon. A similar study with a control group of healthy children is needed to assess the burden of the disease attributed to each pathogen.

Cytokine response in asymptomatic and symptomatic Plasmodium falciparum infections in children in a rural area of south-eastern Gabon.

Plasmodium falciparum is a parasite that causes asymptomatic or symptomatic malaria infections in humans depending on various factors. These infections are also a major cause of anemia in intertropical countries such as Gabon. Past studies have clearly demonstrated that inflammatory markers such as cytokines play a key role in the pathogenesis of malaria disease. However, the clinical manifestations of severe malaria vary according to the level of transmission and more information is needed to gain a better understanding of the factors involved. As such, the objective of this study was to investigate the circulating levels of nine cytokines in asymptomatic and symptomatic P. falciparum infections in Gabonese children and their roles in the pathogenesis of anemia. Blood samples were collected from 241 children aged 3 to 180 months in Lastourville, south-eastern Gabon. Diagnosis of P. falciparum infection was performed using Rapid Diagnosis Tests, microscopy and nested PCR. Levels in the plasma of the Th1 (IFN-γ, TNF-α, IL-6 and IL-12p70), Th17 (IL-17A and IL-22) and Th2 (IL-10, IL-4 and IL-13) cytokines were measured by ELISA. Data showed that IL-6, IFN-γ, IL-12p70, IL-10, and IL-13 levels were significantly higher in children with symptomatic P. falciparum infection compared to uninfected children. IL-10 levels were significantly higher in symptomatic children than in asymptomatic children, who had moderately increased levels compared to uninfected controls. Moreover, only IL-10 and IL-6 levels were significantly higher in children with severe malarial anemia compared to children with uncomplicated malaria who had significantly lower IL-10 levels than children with moderate malarial anemia. These data indicate that the progression of P. falciparum infection towards an advanced stage in children is accompanied by a significant increase in type Th1 and/or Th2 cytokines. These inflammatory mediators could serve as potential predictors of anemia for malaria patients.

Intermittent preventive treatment and malaria amongst pregnant women who give birth at the Centre Hospitalier Régional Paul Moukambi de Koula-Moutou in southeastern Gabon

BackgroundEvaluating malaria control strategies for pregnant women is essential. The objective of this study was to determine the factors influencing antenatal care (ANC) visit attendance, complete intermittent preventive treatment with sulfadoxine-pyrimethamine (IPTp-SP) and its impact on the health of pregnant women and their newborn babies living in semi-urban and rural areas of southeastern Gabon.MethodsThis transversal study was performed at the Centre Hospitalier Régional Paul Moukambi de Koula-Moutou (CHRPMK). Information regarding age, frequency of prenatal consultations, obstetric history, use of malaria control measures, use of IPTp-SP, malaria diagnostic of women and their newborns, were collected: (i): from birth registers from 1 January, 2018 to 31 December, 2019 and, (ii): a questionnaire from January to April 2020.ResultsIn total, 1,851 and 323 pregnant women were included during the first and the second sub-set of study, respectively. In the first sub-set of data, the mean age was 26.18 ± 7.02 years and 96.54% (1,787/1,851) of pregnant women had attended ANC service but 54.45% had complete ANC visit attendance (at least 4 ANC). The complete ANC visit was linked with age (p < 0.001) and profession (p < 0.001). The complete IPTp-SP (at least 3 doses) was 58.87%. Complete IPTp-SP was linked to profession (aOR = 1.49, 95% CI [1.04–2.18], p < 0.001), ANC visit (aOR = 0.176, 95% CI [0.14–0.22], p < 0.034) and age (p = 0.03). Birth weight was higher for babies whose mothers had received complete IPTp-SP (p < 0,001) but the Apgar score was not influenced by the use of IPTp-SP (p = 0.71). In the second sub-set of data, the prevalence of plasmodial infection was 3.10% (95% IC [1.21–5]) and Plasmodium falciparum was responsible for 100% of infections. The prevalence of plasmodial infection was the same for all age groups (p = 0.69), gravidity (p = 0.13) and domestic control measures (p > 0.05). A low birth weight was statistically linked to the mother’s plasmodial infection (p < 0.01). Furthermore, plasmodial infection was statistically linked to premature birth (p < 0.001).ConclusionsIt was observed that attendance of women to ANC service and a complete IPTp-SP course is insufficient.

New evidence on the role of past human activities and edaphic factors on the fine-scale distribution of an important timber species: Cylicodiscus gabunensis Harms

Despite the implementation of management plans, commercial tree species densities are declining in the forests of Central Africa. In the region, Cylicodiscus gabunensis Harms (Fabaceae-Caesalpinioideae; common name ‘okan’), is one such species most exploited, but its ecology remains poorly understood. The rarity of its regeneration in evergreen forest suggests that, like other commercial light-demanding species, the conditions that allowed populations to become established are no longer present. Using a combined archaeobotanical and pedological approach, the aim of this study is to identify the factors explaining the current distribution of C. gabunensis individuals at local scale. Within a plot of 1050 ha in a forest concession in south-eastern Gabon, we installed 40 archaeological pits equally divided between sites with and without C. gabunensis. The artefacts encountered were collected and analysed. Charcoal masses were quantified and 18 charcoals were dated. These ages were compared with the average age of the tree population, using growth data from 50 individuals and heartwood dating from 4 individuals. An analysis of the physico-chemical properties of the soil was carried out on composite samples from each archaeological pit. Pottery sherds were found in two pits while charcoal was present in all pits, suggesting widespread human occupation and fire throughout the study area. Human occupation occurred in two phases: between 2480 and 1010 BP and from 590 to 80 BP. The abandonment of agricultural land at the end of this second phase could coincide with the establishment of the C. gabunensis cohort whose average age has been estimated at between 90 and 148 years. Soil analyses showed that C. gabunensis individuals were located on soils that were comparatively richer in element potentially toxic (Fe) and in some plant nutrients (K, P) and total nitrogen. The current scarcity of young trees argues for the implementation of a silviculture that integrates the light requirements of the species as well as the chemical fertility of the soil.

Effect of problem-based learning strategy on upper basic education Students interest, achievement and cognitive load in basic science in Katsina-ala local government area

Introduction: With a high burden among pregnant women and children under five years of age, malaria infection remains a real health problem, for these vulnerable segments of the population. The objective of this study was to assess the prevalence of malaria infection in children aged 0-5 years attending the Moanda medical centre in south-eastern Gabon. Methods: A retrospective, descriptive and cross-sectional survey was conducted among children aged 0-5 years who came to the Moanda medical centre in January to December 2021, using the results of microscopic examinations (thick drops) recorded in the laboratory registers of the centre. Results: Out of 770 children aged 0 to 5 years registered for this study, 302 were positive for malaria infection, a total prevalence of 39.22%. With a mean age of 24.21 months, boys (415 cases, 53.90%) were more prevalent than girls (355 cases, 46.10%). While the 0-12 months age group was in the majority with 113 cases of malaria infection, i.e. 37.42%, the study showed no significant correlation between gender, age groups and malaria infection. The distribution of malaria infection by type of quater showed that it was more prevalent in the under-integrated (disadvantaged) quaters with n=182, i.e. 60.26% cases, than in the integrated quaters. The seasonal evolution of malaria infection according to age groups revealed two peaks, which represented periods of higher prevalence. The periods between the months of February and March, which are included in the short rainy season, and the month of June, which had the highest peak, corresponding to the long dry season. Conclusion: The prevalence of malaria infection in the study area showed seasonal variation during the study period. The results of this survey may be useful for a future update of the epidemiological profile of malaria infection in children aged 0-5 years. This may be essential to guide resource allocation, evaluation and prioritisation of malaria interventions at Moanda Medical Centre.

First Assessment of Nocturnal Lepidopteran Communities in the Forest Savannah Mosaic of the Plateaux Batéké, Southeastern Gabon

Lepidopterans are an important component of central African biodiversity. Indeed, they play an important role as plant pollinators, food source, bio-indicators, and even pests for local crops. However, almost nothing is known about these moths in central Africa, while they are being increasingly threatened by significant landscape changes due mainly to infrastructure constructions and climate change. So, the mosaic of forests and savannah in the Plateaux Batéké (southeastern Gabon) constitutes a unique opportunity to study how Lepidopteran communities might evolve along an ecological gradient with upcoming changes in forest cover in the region. A total of 2824 specimens, representing 14 distinct families or subfamilies, were sampled using light-trapping and sorted into morphospecies, while a subset of 95 samples was further investigated using both morphological and molecular methods. Community comparison of nocturnal Lepidopteran showed that there was a significant difference in terms of abundance only between sampling sessions. Indeed, this could be due to food availability between sampling sessions. In May and June in Gabon, most plants have flowers and fruits and moth families such as Geometridae and Sphingidae emerge at that time. The most represented family in our sampled specimens was the Geometridae, which prefers habitats with permanent river courses as is the case in our sampling area. However, a more comprehensive study using various trapping methods, during several seasonal cycles and with more replicates in each habitat type is needed for a better understanding of the community structure and ecological traits that characterize nocturnal Lepidopteran in the Plateaux Batéké of Gabon.

Flower morphological differentiation and plant-pollinator interactions among sympatric Aframomum species (Zingiberaceae) with floral trumpet type in the tropical African rainforest

Background and aims – Diversification in plant-pollinator interactions based on floral diversity is potentially a mechanism of coexistence in angiosperms. However, besides high floral diversity, some genera seemingly exhibit the same floral type in many of their species. This contradicts some expectations of competitive exclusion. We thus tested on a finer flower morphological scale whether five sympatric Aframomum species (61 spp., Zingiberaceae) in southeastern Gabon exhibiting the same general floral type (trumpet) were differentiated, and whether this resulted in different “pollinator niches”.Material and methods – We carried out a detailed survey measuring 18 flower morphological parameters as well as nectar volume (μl) and sugar concentration (% Brix) on five flowers per species and locality. Furthermore, we observed inflorescence phenology and pollinator activity from 8 am to 4 pm for 12 to 50 hours per species and conducted pollinator exclusion experiments.Key results – This study proves fine-scale flower morphological and resource differentiation within the trumpet floral type. Pollination-relevant parts of the flowers, however, remain constant across species. Our pollinator observations reveal the same broad bee pollinator spectrum for all observed simultaneously flowering sympatric species.Conclusion – As we could not detect a pollinator-based differentiation in the studied sympatric Aframomum species we assume that species boundaries developed randomly by genetic drift during geographic isolation in the past. The trumpet floral type and its pollinator guild, however, were maintained due to similar selection pressures in comparable habitats during isolation and are potentially an advantage for increased pollinator attraction through co-flowering.

Inflammatory cytokine responses in children with asymptomatic malaria infection living in rural, semi-urban and urban areas in south-eastern Gabon.

Cytokines are soluble mediators of the immune response, and their evolution influences the disease outcome. Gaining knowledge on cytokines has become important, as they can constitute biomarkers allowing the diagnosis of malaria and preventing severe forms of the disease. Here, we investigated 10cytokines and their circulating levels in asymptomatic Gabonese children with Plasmodium falciparum infection living in urban, semi-urban and rural areas. Blood samples were collected from 273 schoolchildren (153 uninfected and 120 infected) aged 6 to 192months. Hematological parameters were determined and P. falciparum diagnosis was performed using a rapid diagnosis test, microscopy and nested polymerase chain reaction (PCR). Plasma pro- [interferon (IFN)-γ, tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-12p70, IL-17A and IL-22] and anti-inflammatory [IL-10, IL-4, IL-13 and transforming growth factor (TGF)-β] cytokine levels were measured by enzyme-linked immunosorbent assay (ELISA) and compared between asymptomatic-infected and uninfected children. Results revealed that without distinction of area, IL-10 and IL-6 levels were higher in infected compared to uninfected children; however, the pro- and anti-inflammatory ratios (IL-6/IL-10 and TNF-α/IL-10) were similar. Furthermore, with area distinction significantly elevated levels of IL-10 in these asymptomatic children were always accompanied by either significantly low or high levels of a proinflammatory cytokine. Also, comparison between asymptomatic-infected children from the three areas showed significantly lower IL-17A, IL-22 and TGF-β levels in urban area compared to semi-urban and rural areas. These results suggest that asymptomatic malaria infections induce significantly high inflammatory cytokine levels without modifying the balanced between pro- and anti-inflammatory cytokines and underline the higher exposure to infections of children in rural areas.

Population Structure, Growth Dynamics, Leaf Production and Soil Conditions of Megaphrynium macrostachyum, a Key Non-Wood Forest Product in Central Africa

Aims: Megaphrynium macrostachyum is a key non-wood forest product (NWFP) in Central Africa. This study aims to describe the soil characteristics and behaviour of the species Megaphrynium macrostachyum in a fallow land in southeastern Gabon.&#x0D; Methodology: Leaf growth was monitored weekly on a sample of 60 leaves for 10 weeks, after the unrolling of horns. Population structure and leaf production were quantified on 64 m² plots and then extrapolated to the hectare. Soil samples were collected at 30 cm depth.&#x0D; Results: Leaf growth and stem enlargement were observed to take place during the horn stage, while stem elongation became active after this stage. The stem reached its maximum height about 60 days after the leaf had fully unrolled. Within the same population, leaf length and leaf width were less heterogeneous (on average 55.6 ± 5.9 cm and 35.5 ± 4.5 cm, respectively); whereas leaf area, stem diameter and stem height were quite heterogeneous (on average 1475 ± 328.3 cm², 9 ± 2.2 mm and 154 ± 33.3 cm, respectively). Megaphrynium macrostachyum was observed to colonise its environment quite well (148,646 ± 66,623 stems per hectare), thus explaining its high leaf production (104,167 ± 45,271 usable leaves per hectare). The soil sample analysed revealed Megaphrynium macrostachyum to grow in sandy-silty or sandy-silty-clay soils (58.21% sand, 25.69% silt and 16.1% clay), and in soils that are wet (35% relative humidity), acidic (pH 4.01), low in phosphorus (9.38 ppm assimilable phosphorus) and total nitrogen (0.01% total nitrogen), and high in organic matter (19.3% organic matter).&#x0D; Conclusion: The leaf area exploited by local populations is variable. Megaphrynium macrostachyum is less demanding on soil characteristics, with high leaf production. From a cultivation perspective, the horn stage would be decisive.

Diversity of parasites in two captive chimpanzee populations in southern Gabon.

Captive chimpanzees living in confined environments like sanctuaries or primatology centers are frequently affected by gastrointestinal parasites. Some of these are likely to be transmitted to humans and may seriously affect public health. However little information is currently available on the gastrointestinal parasites of primates living in such environments. Here, we characterize the diversity and prevalence of gastrointestinal parasites in two populations of captive chimpanzees living in south-eastern Gabon. Our study reveals that at least nine parasite species infect the chimpanzees with high prevalence, including several helminths (Ascaris spp., Enterobius spp., Strongyloides spp., Trichuris spp., Hymenolepis spp., Mammomonogamus spp), three protozoa (Balantioides spp., Entamoeba spp. and Troglodytella spp) and several unidentified parasites. All the parasite taxa we identified had previously been identified in other primates, including humans. Age, sex and site type may influence infection rates and/or parasite diversity found in a particular host.

Vulvovaginal candidiasis among symptomatic women of childbearing age attended at a Medical Analysis Laboratory in Franceville, Gabon

BackgroundVulvovaginal candidiasis (VVC) is one of the most common lower genital tract infections in women; this unpleasant and extremely embarrassing pathology is one of the main reasons for gynaecological consultation. In Gabon, the prevalence of VVC remains poorly described even though VVC is known to be the leading gynaecological condition in several countries. This retrospective cross-sectional study sought to assess the prevalence of VVC among symptomatic women in southeastern Gabon. MethodsClinical samples were collected from patients suspected to have VVC during a 2-year period (from January 2016 to December 2017). Gram staining of vaginal smears provided indications of vaginal flora and confirmed the presence of yeast. Sabouraud-chloramphenicol and chromID Candida media were used to isolate yeast, and species identification was performed using morphological tests and the Vitek 2 Compact automated system. ResultsFor the 873 patients included in this study, the prevalence of VVC was 28.52%. Eleven Candida species were identified, with greater representation of Candidaalbicans (82.73%) than of Non C. albicanscandida (NCAC) (17.27%), which were distributed as follows: Candidafamata (4.02%), Candida spp. (3.61%), Candidarugosa (3.21%), Candidalipolytica (1.61%), Candidaparapsilosis (1.61%), Candidaglabrata (1.21%), Candidatropicalis (0.80%), Candidakrusei (0.40%), Candidadubliniensis (0.40%), and Candidasphaerica (0.40%). ConclusionThis study offers the first estimation of VVC among Gabonese women in childbearing age with the symptoms. It showed that VVC is very common in Gabon. C. albicans as the most commonly represented species.

Prevalence of Plasmodium falciparum antimalarial drug resistance genes in Southeastern Gabon from 2011 to 2014.

PurposeThe introduction of artemisinin-based combination therapies (ACTs) in treating uncomplicated malaria and sulfadoxine–pyrimethamine (SP) as intermittent preventive treatment during pregnancy drastically decreased the burden of malarial disease around the world. However, ACTs are known to select for drug resistance markers. In Gabon, artemether–lumefantrine induced an increase in the prevalence of N86-Pfmdr1, which is associated with treatment failure. However, little data are available regarding resistance markers in Southeastern Gabon. This study aimed to evaluate the evolution of resistance haplotypes in the Pfcrt, Pfdhps, Pfdhfr, and PfK13 genes from 2011 to 2014 in Southeastern Gabon.MethodsA total of 233 Plasmodium falciparum DNA samples were collected from febrile pediatric patients in South Gabon: Franceville, an urban area; Koulamoutou, a semi-urban area; and Lastourville, a rural area. Pfcrt, Pfdhps, Pfdhfr, and the propeller domain of PfK13 were sequenced for all isolates.ResultsThe overall prevalence (3.7%–11.5%) of the wild-type haplotype Pfcrt 72-76 CVMNK was not significantly different between 2011 and 2014 in Southeast Gabon. For Pfdhfr (codons 51, 59, 108, 164), the IRNI triple-mutant haplotype was the most prevalent (>89.0%). The ICNI and NCNI mutant haplotypes and the NCSI wild-type haplotype showed a minor prevalence. There were no differences in the distributions of these haplotypes across the 4 years and the three study sites. For Pfdhps, the AAKAA and SGKAA mutant haplotypes and the SAKAA wild-type haplotype were similarly present in the three areas during the study period. The AGKAA double mutant was first observed in 2013 in Franceville and in 2014 in Koulamoutou and Lastourville. Interestingly, only the A578S mutation (0.4%) and two new A494V (0.4%) and V504A (0.9%) mutations were found in PfK13.ConclusionDespite the withdrawal of chloroquine, the frequency of the resistant allele 76T remained high in the south of Gabon. Moreover, a high level of resistant haplotypes against IPTp-SP was found.

Pfmdr1 gene polymorphism of Plasmodium falciparum isolates from asymptomatic individuals of Dienga, southeastern Gabon

Background: In Gabon, studies on molecular epidemiology of malaria are mainly confined to urban and hospital settings; contrasting with rural areas where data are scarce, especially on asymptomatic P. falciparum infection. In this study, the polymorphism of P. falciparum multidrug resistance -1 gene (Pfmdr1) was investigated for the first time in P. falciparum specimens from asymptomatic individuals living in Dienga, a rural area in southeastern Gabon. Methods: P. falciparum specimens collected in 2013 and 2014 and diagnosed by standard microscopy (microscopic infection=MI) or by PCR (submicroscopic infection=SMI) were used in this study. The codons 86, 184 and 1246 of Pfmdr1 of P. falciparum specimens were genotyped by PCR and RFLP. Results: Among the three codons 86, 184 and 1246 of Pfmdr1, the wild-type alleles were the most prevalent in 2014. The frequency of mixed genotype N86Y was 19.23% in 2013 and 25.28% in 2014. The frequency of D1246Y mixed genotype was 10.40% in 2013 and 17.24% in 2014. On the other hand, no mixed genotype was observed for the codon 184. The most frequent haplotypes identified were NFY (33%) in 2013 and YYD (30.0%) in 2014. The frequencies of other haplotypes (YYY, YFD, NYD, YFY, NFD and NYY) did not show significant difference between 2013 and 2014. Conclusion: Data from Dienga showed moderate variations in the distribution of Pfmdr1 genotypes and a high haplotype diversity suggesting the low ACT drug pressure on parasites in this locality.