Populations In Gabon Research Articles

Eosinophils, basophils and myeloid-derived suppressor cells in chronic Loa loa infection and its treatment in an endemic setting.

Chronic infection by Loa loa remains an unsolved immunological paradox. Despite harboring subcutaneously migrating adult worms and often high densities of microfilariae, most patients experience only relatively mild symptoms, yet microfilaricidal treatment can trigger life-threatening inflammation. Here, we investigated innate cell populations hypothesized to play a role in these two faces of the disease, in an endemic population in Gabon. We analyzed numbers and activation of eosinophils and basophils, as well as myeloid-derived suppressor cell (MDSC) subsets and associated circulating cytokine levels by flow cytometry in sex- and age-matched L. loa-uninfected (LL-), -amicrofilaraemic (MF-) and -microfilaraemic (MF+) individuals (n = 42), as well as microfilaraemic individuals treated with albendazole (n = 26). The percentage of eosinophils was lower in LL- (3.0%) than in the combined L. loa-infected population, but was similar in MF+ (13.1%) and MF- (12.3%). Upon treatment of MF+, eosinophilia increased from day 0 (17.2%) to day 14 (24.8%) and had decreased below baseline at day 168 (6.3%). Expression of the eosinophil activation marker CD123 followed the same pattern as the percentage of eosinophils, while the inverse was observed for CD193 and to some extent CD125. Circulating IL-5 levels after treatment followed the same pattern as eosinophil dynamics. Basophil numbers did not differ between infection states but increased after treatment of MF+. We did not observe differences in MDSC numbers between infection states or upon treatment. We demonstrate that both chronic infection and treatment of L. loa microfilaraemia are associated with eosinophil circulation and distinct phenotypical activation markers that might contribute to inflammatory pathways in this setting. In this first ever investigation into MDSC in L. loa infection, we found no evidence for their increased presence in chronic loiasis, suggesting that immunomodulation by L. loa is induced through other pathways.

Phytochemical study of Barteria fustolisa mast bark traditionally used against infantile colics by local population in Gabon

Phytochemical study of Barteria fustolisa mast bark traditionally used against infantile colics by local population in Gabon

Phytochemical study of Barteria fustolisa mast bark traditionally used against infantile colics by local population in Gabon

Phytochemical study of Barteria fustolisa mast bark traditionally used against infantile colics by local population in Gabon

Trend of expansion of SARS-CoV-2 infection and COVID-19 burden in Gabon (Central Africa) in mid-2021, based on a serological survey

ObjectiveTo estimate the seroprevalence of anti-SARS-CoV-2 antibodies in the general population in Gabon, Central Africa.MethodsFrom May to July 2021, a cross-sectional study involving participants recruited in the general population in three districts in Gabon was conducted. Eligible participants who provided written informed consent were tested for anti-SARS-CoV-2 antibodies using a simple rapid diagnostic assay.ResultsOverall, 1609 participants were recruited, 1361 (84.6%) from urban sites and 248 (15.4%) from a rural area. The estimated overall seroprevalence was 13.1% (95% CI 11.4–14.8%). The risk of seropositivity increased with age, and the prevalence in the different age groups ranged from 12.9% (8.0–19.4%) in those aged 15–24 years to 23.3% (14.2–34.6%) in those ≥ 65 years old. A higher prevalence was found in the rural population (17.3%; 12.8–22.6%) compared with urban regions (12.3%; 10.6–14.1%). Being a woman was also associated with higher risk of infection (p < 0.001).ConclusionsThis seroprevalence survey revealed a moderate seroprevalence in Gabon, illustrating a relatively low rate of circulation of the virus in the country and correlating with low numbers of confirmed cases and deaths reported to date.

Demographic and Clinical Characteristics Associated With Severity, Clinical Outcomes, and Mortality of COVID-19 Infection in Gabon

Since the emergence of COVID-19 in central China, sub-Saharan African countries, with the exception of South Africa, have been relatively spared during the COVID-19 pandemic. Consequently, few descriptive studies from this region are available. To describe the clinical characteristics and outcomes of patients with COVID-19 infection in Gabon, from March to June 2020. A single-center, cross-sectional study of 837 patients with COVID-19 was conducted from March to June 2020 in the Armed Forces Hospital in Libreville, Gabon. Demographic and clinical characteristics and imaging findings of hospitalized patients with COVID-19. Of the 837 patients enrolled, 572 (68.3%) were men, and 264 (31.5%) were women (male to female ratio, 2:1); the median (interquartile range [IQR]) age was 35 (30-45) years (mean [SD] age, 38.0 [12.2] years. The mortality rate associated with COVID-19 was low (1.4%). Of these 837 patients, 524 (62.6%) were categorized as having no symptoms, 282 (33.7%) as having mild symptoms, and 31 (3.7%) as having severe symptoms. Patients with severe symptoms were older (mean [SD] age, 46.1 [14.7] years) than patients with mild symptoms (mean [SD] age, 41.3 [12.5] years) and those with no symptoms (mean [SD] age, 35.7 [11.3] years) (Kruskal-Wallis χ22 = 53.5; P < .001). History of diabetes was the principal risk factor associated with both severe symptoms in 5 of 31 patients (16.1%) and mild symptoms in 11 of 282 (3.9%) compared with no symptoms in 5 of 524 (0.9%) (Pearson χ22 = 30.9; P < .001). Patients with severe symptoms and a fatal outcome were older (mean [SD] age, 53.4 [15.1] years) than survivors (mean [SD] age, 41.5 [12.9] years) (t20.83 = 2.2; P = .03). In this single-center, cross-sectional study in Libreville, Gabon, the mortality rate associated with COVID-19 infection from March to June 2020 was low, and patients who died of COVID-19 infection were younger on average than reported elsewhere, possibly reflecting a smaller elderly population in Gabon.

Immunomics-guided discovery of serum and urine antibodies for diagnosing urogenital schistosomiasis: a biomarker identification study

SummaryBackgroundSensitive diagnostics are needed for effective management and surveillance of schistosomiasis so that current transmission interruption goals set by WHO can be achieved. We aimed to screen the Schistosoma haematobium secretome to find antibody biomarkers of schistosome infection, validate their diagnostic performance in samples from endemic populations, and evaluate their utility as point of care immunochromatographic tests (POC-ICTs) to diagnose urogenital schistosomiasis in the field.MethodsWe did a biomarker identification study, in which we constructed a proteome array containing 992 validated and predicted proteins from S haematobium and screened it with serum and urine antibodies from endemic populations in Gabon, Tanzania, and Zimbabwe. Arrayed antigens that were IgG-reactive and a select group of antigens from the worm extracellular vesicle proteome, predicted to be diagnostically informative, were then evaluated by ELISA using the same samples used to probe arrays, and samples from individuals residing in a low-endemicity setting (ie, Pemba and Unguja islands, Zanzibar, Tanzania). The two most sensitive and specific antigens were incorporated into POC-ICTs to assess their ability to diagnose S haematobium infection from serum in a field-deployable format.FindingsFrom array probing, in individuals who were infected, 208 antigens were the targets of significantly elevated IgG responses in serum and 45 antigens were the targets of significantly elevated IgG responses in urine. Of the five proteins that were validated by ELISA, Sh-TSP-2 (area under the curve [AUC]serum=0·98 [95% CI 0·95–1·00]; AUCurine=0·96 [0·93–0·99]), and MS3_01370 (AUCserum=0·93 [0·89–0·97]; AUCurine=0·81 [0·72–0·89]) displayed the highest overall diagnostic performance in each biofluid and exceeded that of S haematobium-soluble egg antigen in urine (AUC=0·79 [0·69–0·90]). When incorporated into separate POC-ICTs, Sh-TSP-2 showed absolute specificity and a sensitivity of 75% and MS3_01370 showed absolute specificity and a sensitivity of 89%.InterpretationWe identified numerous biomarkers of urogenital schistosomiasis that could form the basis of novel antibody diagnostics for this disease. Two of these antigens, Sh-TSP-2 and MS3_01370, could be used as sensitive, specific, and field-deployable diagnostics to support schistosomiasis control and elimination initiatives, with particular focus on post-elimination surveillance.FundingAustralian Trade and Investment Commission and Merck Global Health Institute.

Epidemiology and Genetic Variability of HHV-8/KSHV among Rural Populations and Kaposi's Sarcoma Patients in Gabon, Central Africa. Review of the Geographical Distribution of HHV-8 K1 Genotypes in Africa.

Human herpesvirus 8 (HHV-8) is the etiological agent of all forms of Kaposi’s sarcoma (KS). K1 gene studies have identified five major molecular genotypes with geographical clustering. This study described the epidemiology of HHV-8 and its molecular diversity in Gabon among Bantu and Pygmy adult rural populations and KS patients. Plasma antibodies against latency-associated nuclear antigens (LANA) were searched by indirect immunofluorescence. Buffy coat DNA samples were subjected to polymerase chain reaction (PCR) to obtain a K1 gene fragment. We studied 1020 persons; 91% were Bantus and 9% Pygmies. HHV-8 seroprevalence was 48.3% and 36.5% at the 1:40 and 1:160 dilution thresholds, respectively, although the seroprevalence of HHV-8 is probably higher in Gabon. These seroprevalences did not differ by sex, age, ethnicity or province. The detection rate of HHV-8 K1 sequence was 2.6% by PCR. Most of the 31 HHV-8 strains belonged to the B genotype (24), while the remaining clustered within the A5 subgroup (6) and one belonged to the F genotype. Additionally, we reviewed the K1 molecular diversity of published HHV-8 strains in Africa. This study demonstrated a high seroprevalence of HHV-8 in rural adult populations in Gabon and the presence of genetically diverse strains with B, A and also F genotypes.

Six years surveillance of Plasmodium falciparum malaria among febrile patients reporting in Centre de Santé d’Okala, North West Gabon

Background : Malaria remains a threat to the health of the population of Gabon based on the high hospitalizations and deaths caused by this disease. This study aimed at determining the prevalence and associated risk factors of malaria in febrile patients visiting the Centre de Sante d’Okala (CSO). Methods : A six years study was conducted on febrile patients seeking for health services at the CSO from the year 2014 to 2019. Blood samples of 2388 patients were tested for antigens specific to Plasmodium falciparum using the Beacon® rapid diagnostic kit. Results : The overall prevalence of P. falciparum malaria was 29.857%. The year 2014 (35.553%) recorded the highest prevalence rate. Individuals from Okala (44.137%) community recorded the highest number of cases. Females (56.886%) had higher infection prevalence than their male (43.114%) counterparts. Children ≤ 10 years old (57.412%) had the highest prevalence rates than other age cohorts. Conclusions : The number of malaria cases reported in the CSO are currently increasing and community sensitisation on preventive measures against this disease is required inorder to flatten the curve of positive cases.

Anaemia in asymptomatic parasite carriers living in urban, rural and peri-urban settings of Gabon.

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. 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. 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 (7.1g/dl [interquartile range {IQR} 6.8-7.5]), Schistosoma intercalatum (6.9g/dl), Trichuris trichiura (10.1g/dl [IQR 8.9-11.5]) and Plasmodium falciparum (10.0g/dl [IQR 9.1-11.2]) compared with filariaemia (12.1g/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. The prevalence of anaemia is high. Asymptomatic parasite carriage is associated with anaemia in this surveyed population in Gabon.

Revisiting human T-cell lymphotropic virus types 1 and 2 infections among rural population in Gabon, central Africa thirty years after the first analysis.

HTLV-1 infection is considered as highly endemic in central Africa. Thirty years ago, a first epidemiological study was performed in Gabon, central Africa, and revealed that the prevalence varied from 5.0 to 10.5%. To evaluate current distribution of HTLVs in Gabon, 4.381 samples were collected from rural population living in 220 villages distributed within the 9 provinces of country. HTLVs prevalence was determined using two ELISA tests and positive results were confirmed by Western Blot. The overall HTLV-1 seroprevalence was of 7.3% among the rural Gabonese population; with 5.4% for men and 9.0% for women. Prevalence of HTLV-1 differed by province, ranging from 2.3% to 12.5% into the rain forest. Being a woman older than 51 years represented a high risk for HTLV-1 acquisition. Hospitalization, operation/surgery, transfusion and medical abortion or fever, arthritis and abdominal pain are also significant risk factors. In addition, 0.1% of samples were found as HTLV-2 positive, while 12.0% had an indeterminate HTLV serological pattern. HTLV-3 and HTLV-4 were not found. Phylogenetic analysis was performed on 87 samples and demonstrated that HTLV-1 present in Gabon belongs mostly to subtype B, however the rare subtype D was also found. Altogether, our results demonstrate that almost thirty years after the first epidemiological study prevention of HTLVs infection is still an issue in Gabon.

Risk factors for HTLV-1 infection in Central Africa: A rural population-based survey in Gabon.

BackgroundHuman T-Lymphotropic Virus type 1 (HTLV-1) is a human oncoretrovirus that infects at least 5 to 10 million people worldwide and is associated with severe diseases. Africa appears as the largest HTLV-1 endemic area. However, the risk factors for the acquisition of HTLV-1 remain poorly understood in Central Africa.MethodsWe conducted an epidemiological survey between 2013 and 2017, in rural areas of 6 provinces of Gabon, in a rainforest environment. Epidemiological data were obtained and blood samples were collected after informed consent. Plasma were screened for HTLV-1 antibodies by ELISA and the positive samples were then tested by Western blot (WB). Genomic DNA derived from buffy-coat was subjected to two semi-nested PCRs amplifying either HTLV-1 env gene or LTR region fragments.ResultsWe recruited 2,060 individuals over 15 years old, including 1,205 men and 855 women (mean age: 49 years). Of these, 299 were found to be ELISA HTLV-1/2 seropositive. According to WB criteria, 136 were HTLV-1 (6.6%), 25 HTLV-1/2 (1.2%) and 9 HTLV seroreactive (0.4%). PCR results showed that 146 individuals were positive for at least one PCR: 104 for the env gene and 131 for the LTR region. Based on both serological and molecular results, 179 individuals were considered infected with HTLV-1, leading to an overall prevalence of 8.7%. The distribution of HTLV-1 infection was heterogeneous across the country. Based on multivariable analyses, female gender, increasing age, ethnicity (Pygmy) and multiple hospitalizations (more than 5 times) were found to be independent risk factors for HTLV-1 infection. Furthermore, a non-human primate bite appeared to be marginally associated with a higher risk of HTLV-1 infection.ConclusionBased on state-of-the-art serological and molecular methods, we have demonstrated that rural adult populations in Gabon are highly endemic for HTLV-1. Our results regarding risk factors should lead to public health actions aiming to reduce HTLV-1 transmission.

Forest elephant movement and habitat use in a tropical forest-grassland mosaic in Gabon.

Poaching of forest elephants (Loxodonta cyclotis) for ivory has decimated their populations in Central Africa. Studying elephant movement can provide insight into habitat and resource use to reveal where, when, and why they move and guide conservation efforts. We fitted 17 forest elephants with global positioning system (GPS) collars in 2015 and 2016 in the tropical forest-grassland mosaic of the Wonga Wongué Presidential Reserve (WW), Gabon. Using the location data, we quantified movement distances, home ranges, and habitat use to examine the environmental drivers of elephant movements and predict where elephants occur spatially and temporally. Forest elephants, on average, traveled 2,840 km annually and had home ranges of 713 km2, with males covering significantly larger home ranges than females. Forest elephants demonstrated both daily and seasonal movement patterns. Daily, they moved between forest and grassland at dawn and dusk. Seasonally, they spent proportionally more time in grassland than forest during the short-wet season when grasses recruit. Forest elephants also traveled faster during the short-wet season when fruit availability was greatest, likely reflecting long, direct movements to preferred fruiting tree species. Forest elephants tended to select areas with high tree and shrub density that afford cover and browse. When villages occurred in their home ranges elephants spent a disproportionate amount of time near them, particularly in the dry season, probably for access to agricultural crops and preferred habitat. Given the importance of the grassland habitat for elephants, maintenance of the forest-grassland matrix is a conservation priority in WW. Law enforcement, outreach, and education should focus on areas of potential human-elephant conflict near villages along the borders of the reserve. GPS-tracking should be extended into multi-use areas in the peripheries of protected areas to evaluate the effects of human disturbance on elephant movements and to maintain connectivity among elephant populations in Gabon.

Spatial and temporal distribution of Pfmsp1 and Pfmsp2 alleles and genetic profile change of Plasmodium falciparum populations in Gabon

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.

Phylogenetic tests of a Cercopithecus monkey hybrid reveal X-chromosomal polyphyly of C. cephus and emerging patterns in the cephus species group radiation

A captive Cercopithecus nictitans × C. cephus male was examined at loci on the X- and Y-chromosomes as a test of previously described phylogenetic methods for identifying hybrid Cercopithecus monkeys. The results confirm the reliability of such assays, indicating that they can be of immediate utility for studies of wild populations in Gabon, where the two species have hybridised. A closer examination of the resultant sex chromosomal topologies, combined with recent mitochondrial studies, reveals two emerging patterns in the evolution of the cephus species group. First, all three genetic systems (X-DNA, Y-DNA and mtDNA) agree that the earliest divergence separates West African from Central African species, consistent with a major faunal transition zone in the vicinity of the Cross River. Second, the X-DNA and mtDNA trees reveal polyphyly of C. cephus lineages. It is unclear at present whether these polyphylies are due to ancestral hybridisation or incomplete lineage sorting, or both.

Mixed connective tissue disease: prevalence and clinical characteristics in African black, study of 7 cases in Gabon and review of the literature

La littérature rapporte que la connectivite mixte semble plus fréquente dans la population noire et chez les asiatiques. Le but de l'étude était de déterminer la prévalence de la connectivite mixte (CM) parmi les connectivites et l'ensemble des pathologies rhumatologiques dans une population hospitalière au Gabon; de décrire ensuite les caractéristiques cliniques de la maladie. Il s'agissait d'une étude rétrospective des dossiers de patients suivis pour connectivite mixte (critères de Kasukawa) et les autres entités de connectivites (critères ACR) en rhumatologie au CHU de Libreville entre janvier 2010 et décembre 2015. Pour chaque cas de CM, les manifestations articulaires et extra-articulaires, le taux d'anticorps anti-U1RNP, l'évolution, étaient les paramètres étudiés. Sept cas ont été colligés en 6 ans parmi 6050 patients et 67 cas de connectivites soit une prévalence de 0,11% et de 10,44% respectivement. Il s'agissait de 7 femmes (100%), d'âge moyen de 39,5 ans. Les signes articulaires comprenaient: polyarthrite, myalgies, doits boudinés et phénomène de Raynaud dans 87,5%, 87,5%, 28,6% et 14% respectivement. Les 7 patients avaient un taux d'anti-U1RNP élevé entre 5 et 35N (N≤7 UI). Un cas de décès par HTAP était constaté. Il s'agit de la série de CM la plus importante rapportée en Afrique noire. La maladie semble rare chez le noir africain, la raison pourrait être génétique. Les aspects démographiques et cliniques paraissent similaires chez les caucasiens, les asiatiques et les noirs hormis une faible fréquence du phénomène de Raynaud chez les noirs.

Seroprevalence of Toxocara spp. in a rural population in Central African Gabon

Toxocara spp. are zoonotic parasites with global distribution infecting humans by incidental ingestions of eggs shed in feces of dogs or cats. High seroprevalences have been reported from several regions of Africa, however data from the Central African region remain limited. Although several clinical entities caused by larvae of Toxocara spp. have been described, the public heath impact of this infection has so far often been neglected. This study was conducted to estimate the prevalence in a rural central African population.The population based study was performed in volunteers in a rural region of Gabon. A two-step testing approach was applied using an ELISA as screening test and a Western Blot (immunoblot) as confirmatory assay. Basic demographic data and risk factors were collected and compared between seropositive and negative participants.In total, 199 out of 332 serum samples were tested positive for Toxocara spp. antibodies (59.9%). After standardization for age to the overall Gabonese population seroprevalence was 53.6% (95% CI 48.2–59.0%). There was a trend towards higher seroprevalence in participants with agricultural activity.Seroprevalence of antibodies against Toxocara spp. is high in this rural population in Gabon. These results are comparable with previous reports from other sub-regions of Africa and add to our understanding of the epidemiology of toxocariasis in Africa. Given the high prevalence of toxocariasis in tropical regions, it may be speculated that clinically relevant presentations (e.g. visceral or ocular larva migrans syndrome) may occur in considerable numbers. A formal assessment of the burden of disease and the public health impact of human toxocariasis is therefore warranted.

Assessment of the effect of Schistosoma haematobium co infection on malaria parasites and immune responses in rural populations in Gabon: study protocol.

BackgroundMalaria and helminth co infection are common in tropical and subtropical areas where they affect the life of millions of people. While both helminth and malaria parasites have immunomodulatory activities, little is known about the consequence of co-infections on malaria antigen specific immune responses.Method/DesignThis study will be conducted in two rural areas of the Moyen Ogooué province in Gabon, endemic for both Plasmodium falciparum and Schistosoma haematobium infections. Participants, 5 to 50 years old, will be enrolled and grouped according to their infection status. S. haematobium and malaria parasites will be detected, demographic and clinical data will be recorded and blood will be collected for hematological as well as for immunological assays. The level of antibody specific to Plasmodium falciparum blood stage and gametocyte antigens will be measured using ELISA. PBMC will be isolated for phenotyping of different T cell subsets ex vivo by flow cytometry and for culture and cytokine response assessment.DiscussionWe will provide a comprehensive picture of the interaction between schistosomes and malaria parasites which co-localize in peripheral blood. We will test the hypothesis that schistosome infection has an impact on specific humoral as well as on cellular immune responses to malaria antigens.

Prevalence, genetic diversity and antiretroviral drugs resistance-associated mutations among untreated HIV-1-infected pregnant women in Gabon, central Africa

BackgroundIn Africa, the wide genetic diversity of HIV has resulted in emergence of new strains, rapid spread of this virus in sub-Saharan populations and therefore spread of the HIV epidemic throughout the continent.MethodsTo determine the prevalence of antibodies to HIV among a high-risk population in Gabon, 1098 and 2916 samples were collected from pregnant women in 2005 and 2008, respectively. HIV genotypes were evaluated in 107 HIV-1-positive samples to determine the circulating subtypes of strains and their resistance to antiretroviral drugs (ARVs).ResultsThe seroprevalences were 6.3% in 2005 and 6.0% in 2008. The main subtype was recombinant CRF02_AG (46.7%), followed by the subtypes A (19.6%), G (10.3%), F (4.7%), H (1.9%) and D (0.9%) and the complex recombinants CRF06_cpx (1.9%) and CRF11_cpx (1.9%); 12.1% of subtypes could not be characterized. Analysis of ARVs resistance to the protease and reverse transcriptase coding regions showed mutations associated with extensive subtype polymorphism. In the present study, the HIV strains showed reduced susceptibility to ARVs (2.8%), particularly to protease inhibitors (1.9%) and nucleoside reverse transcriptase inhibitors (0.9%).ConclusionsThe evolving genetic diversity of HIV calls for continuous monitoring of its molecular epidemiology in Gabon and in other central African countries.

Haematological and biochemical reference intervals for infants and children in Gabon

To establish reference intervals for major haematological and biochemical parameters in Gabonese infants and children. The reference sample population consisted of 226 healthy infants (4-9 weeks of age) and 185 healthy children (18-60 months of age). Basic red cell parameters as well as total and differential white blood cell counts were performed. Clinical chemistry parameters consisted of glutamate-pyruvic transaminase and creatinine, and total bilirubin was measured in children. Statistical analysis was based on the guidelines of the Clinical and Laboratory Standards Institute. Nonparametric methods were used to determine 95% reference limits and their 90% confidence intervals. Compared to European populations, values for several red cell parameters (haemoglobin, haematocrit, red blood cell count, mean corpuscular volume) were lower and platelet counts were higher. Eosinophils were higher in the older age group, most likely caused by intestinal helminths. The study confirms the importance of establishing reference limits for local populations. The reference ranges could be used as a benchmark for similar populations in Central Africa.

Rift Valley Fever Virus Seroprevalence in Human Rural Populations of Gabon

BackgroundRift Valley fever (RVF) is a mosquito-borne viral zoonosis caused by a phlebovirus and transmitted by Aedes mosquitoes. Humans can also be infected through direct contact with blood (aerosols) or tissues (placenta, stillborn) of infected animals. Although severe clinical cases can be observed, infection with RVF virus (RVFV) in humans is, in most cases, asymptomatic or causes a febrile illness without serious symptoms. In small ruminants RVFV mainly causes abortion and neonatal death. The distribution of RVFV has been well documented in many African countries, particularly in the north (Egypt, Sudan), east (Kenya, Tanzania, Somalia), west (Senegal, Mauritania) and south (South Africa), but also in the Indian Ocean (Madagascar, Mayotte) and the Arabian Peninsula. In contrast, the prevalence of RVFV has rarely been investigated in central African countries.Methodology/Principal FindingsWe therefore conducted a large serological survey of rural populations in Gabon, involving 4,323 individuals from 212 randomly selected villages (10.3% of all Gabonese villages). RVFV-specific IgG was found in a total of 145 individuals (3.3%) suggesting the wide circulation of Rift Valley fever virus in Gabon. The seroprevalence was significantly higher in the lakes region than in forest and savannas zones, with respective rates of 8.3%, 2.9% and 2.2%. In the lakes region, RVFV-specific IgG was significantly more prevalent in males than in females (respectively 12.8% and 3.8%) and the seroprevalence increased gradually with age in males but not in females.Conclusions/SignificanceAlthough RVFV was suggested to circulate at a relatively high level in Gabon, no outbreaks or even isolated cases have been documented in the country. The higher prevalence in the lakes region is likely to be driven by specific ecologic conditions favorable to certain mosquito vector species. Males may be more at risk of infection than females because they spend more time farming and hunting outside the villages, where they may be more exposed to mosquito bites and infected animals. Further investigations are needed to determine the putative sylvan cycle of RVFV, including the mosquito species and the reservoir role of wild animals in the viral maintenance cycle.