Jean-Claude Biteghe-Bi-Essone

Malaria is highly prevalent in Gabon. The objective of this study was to assess adherence to WHO recommendations in the management of paediatric malaria in Franceville, south-east Gabon, and to identify factors influencing clinical decision making. This was a prospective observational study conducted from January 2021 to July 2023. Information regarding clinical examination, thick blood smear results, and the prescription of antimalarial drugs of paediatric children were collected anonymously following informed consent from parents or legal guardians. Data were analysed using R software (version 4.0.5), with descriptive statistics, Chi-square tests, and binary logistic regression to estimate crude and adjusted odds ratios with 95% confidence intervals at a significance level of p < 0.05. A total of 3,195 children aged 0-16 years presenting with fever or a history of fever were included. Overall, 41.6% of patients tested positive by thick blood smear, and 21.4% of them had severe malaria. Despite negative thick blood smear results, 86.7% of patients received a presumptive diagnosis and 98.8% of them were treated with antimalarials. Symptoms significantly associated with a presumptive diagnosis were asthenia (aOR = 1.41; 95% CI [1.01–2.00]), headache (aOR = 1.71; 95% CI [1.02–3.03]), and nausea-vomiting (aOR = 1.95, 95% CI [1.20–3.31]). Despite access to parasitological testing, presumptive diagnosis remains common, exposing patients to potential overprescription and increased risk of drug resistance. Strengthening diagnostic capacity and continuous training of healthcare providers are essential to improve case management.

Background: Urogenital schistosomiasis is endemic in Gabon. Our study aimed to detect the prevalence of urinary schistosomiasis and to evaluate the diagnostic performance of the qPCR technique compared to microscopy for the detection of Schistosoma haematobium at the community level in a semi-rural area. Method: A cross-sectional survey was carried out. Urine samples were examined using Urine TICK test strips, a filtration technique, and qPCR. Schistosoma haematobium was detected by targeting the Dra1 gene. Results: The prevalence of urogenital schistosomiasis was determined and the performance of real-time PCR and urine strips was compared with that of urinary filtration. A total of 281 participants were enrolled in the study. The prevalence of urogenital schistosomiasis was increased slightly with the molecular technique (40.9%) compared to microscopy (36.7%), and the hematuria rate with Urine STICK was 33.5%. SAC (5–14 years old), Pre-SAC (>5 years old), and adolescents (15–17 years old) were the most affected group according to, respectively, whatever method was used. qPCR showed good agreement with microscopy, as well as excellent sensitivity (99.03%) and specificity (93.3). There was a good correlation between the number of eggs per 10 mL and the cycle threshold range. Conclusion: These results show the importance of using a combination of diagnostic tools in the surveillance of schistosomiasis, particularly in preschool children, adolescents, women of childbearing age, and chronic and asymptomatic cases.

Seroconversion surveys of anti-SARS-CoV-2 antibodies provide accurate estimates of the SARS-CoV-2 infection. This nationwide population-based cross-sectional serosurvey aimed to evaluate the prevalence of SARS-CoV-2 antibodies among residents in Gabon and compare the estimated cumulative number of COVID-19 cases with the officially registered number of laboratory-confirmed cases up to December 2021. Households in each province were randomly selected. Twenty-eight localities including 16 urban and 12 rural, were randomly selected to participate in the study. Whole blood samples were collected in dry tubes from all study participants around the country within 15 days. Serum samples were used to measure the total Immunoglobulin antibodies. Overall, data of 1672 households were analyzed. Out of the 3659 participants, 3175 were found positive for SARS-CoV-2 antibodies, resulting in a crude seroprevalence of 86.77%. Stratification of study participants by age group has shown highest seroprevalences in 20–29 and 40-49 age groups with 91.78% (95% CI:89.5–93.6) and 91.42% (95% CI:88.7–93.5), respectively. Nyanga province had the lowest prevalence (72,8%), and Estuaire and Ogoué-Lolo provinces had the highest prevalence (90 and 92%, respectively). Our results suggest a high transmission rate in the Gabonese population, 21 months after the first SARS-CoV-2 case in the country. This high seroprevalence estimate could indicate that the applied infection control measures may not have been adequately implemented or appropriately adhered to by the population.

A better understanding of malaria epidemiology in both asymptomatic and symptomatic individuals is essential for developing strategies to control the disease. This study was conducted to determine Plasmodium infection prevalence and its associated factors among people living in Franceville (urban area) and in the villages of Pana and Mvengue (rural areas) in south‐east Gabon between April and July 2022. This cross‐sectional study was conducted among all consenting residents of Franceville, Mvengue, and Pana between April and July 2022. After obtaining informed consent, Plasmodium sp. infection was screened by microscopy, and a structured questionnaire was developed to record sociodemographic data, attitudes, and practices regarding malaria. A total of 976 participants were included, with 491 in urban areas and 485 in rural areas. The overall prevalence of Plasmodium sp. infection was 21.62% (211/976; 95% confidence interval (CI) [19.15–24.31]). The prevalence was highest in children aged 6–11 years. In urban areas, the prevalence was 19.35% (95/491; 95% CI [16.10–23.07]), and 96.84% of infections were asymptomatic. The most infected age group was 18–23 years. In rural areas, the prevalence was 23.92% (116/485, 95% CI [20.34–27.91], and 93.97% (109/116) of infections were asymptomatic. Socioeconomic characteristics, attitudes, and practices towards Plasmodium sp. infection were not associated with a risk of asymptomatic malaria infection. This study highlights the importance of asymptomatic Plasmodium sp. infection in south‐east Gabon and the need for control strategies adapted to different areas and age groups. Detection and treatment of asymptomatic carriers could be an important lever for malaria control and elimination in the country.

Due to the difficulty of obtaining blood samples, which is the invasive method that is currently used for the detection of Plasmodium spp., alternative diagnostic sampling methods that are effective and non-invasive are needed, particularly for long-term studies. Saliva and stool samples from malaria-infected individuals contain trace amounts of Plasmodium DNA and therefore could be used as alternatives. Malaria was screened using rapid diagnosis tests and confirmed via microscopy. Nested PCR tests targeting the Plasmodium falciparum-specific STEVOR gene were performed for blood, saliva and stool samples that were positive for malaria. Three hundred sixty-seven (367) children were enrolled and eighty (22.22%) were confirmed to be positive for malaria. Matched blood, saliva and stool samples were available for 35 children. By using blood smears as the gold standard for the diagnosis of malaria, our study indicates that Plasmodium DNA was more detectable in blood (100%) than in saliva (22.86%) and stools (14.29%). Applying qPCR to the STEVOR gene to detect Plasmodium falciparum DNA in saliva and stool samples cannot be considered as an alternative to the current malaria detection processes using blood specimens.

Oxidative stress and inflammation play a key role in the occurrence of neurodegenerative diseases. Traditionally, Pentaclethra eetveldeana leaves are used in dementia treatment. Therefore, this study aimed to evaluate the antioxidant and anti-inflammatory activities as well as the phytochemical composition of Pentaclethra eetveldeana leaves from four Congo-Brazzaville regions. The 1.2-diphenyl-1-picrylhydrazyl radical-scavenging, β-carotene bleaching and molybdenum reduction assays were used to assess the antioxidant activity. The protein denaturation and erythrocyte membrane stabilization tests were used to analyze the anti-inflammatory activity. Phytochemical screening, the quantification of polyphenols by spectrophotometry, as well as the determination of extraction yields were carried out. It was found that the extracts reduced molybdenum; furthermore, compared to ascorbic acid, they showed better antiradical activity and inhibited lipid peroxidation. Moreover, globally, the membrane-stabilizing power of the aqueous extracts was superior or comparable to diclofenac, while the same extracts were less effective for the inhibition of denaturation. All of the aqueous extracts contained polyphenols, saponins, alkaloids, anthraquinones, reducing sugar and cardiotonic glycosides. The total polyphenols, tannins and proanthocyanidins are produced proportionally from one region to another. Finally, the leaves from Brazzaville and Boundji contain flavonols, while those from Makoua and Owando contain flavones. Thus, Pentaclethra eetveldeana leaves contribute to traditional dementia treatment through their antioxidant and anti-inflammatory properties.

Plasmodium falciparum infection can progress unpredictably to severe forms including respiratory distress and cerebral malaria. The mechanisms underlying the variable natural course of malaria remain elusive. The cerebral microvascular endothelial cells-D3 and lung endothelial cells both from human were cultured separately and challenged with P. falciparum field isolates taken directly from malaria patients or 3D7 strain (in vitro maintained culture). The capacity of these P. falciparum isolates to induce endothelial cell apoptosis via cytoadherence or not was then assessed. Overall, 27 P. falciparum isolates were collected from patients with uncomplicated malaria (n = 25) or severe malaria (n = 2). About half the isolates (n = 17) were able to bind brain endothelial cells (12 isolates, 44%) or lung endothelial cells (17 isolates, 63%) or both (12 isolates, 44%). Sixteen (59%) of the 27 isolates were apoptogenic for brain and/or lung endothelial cells. The apoptosis stimulus could be cytoadherence, direct cell-cell contact without cytoadherence, or diffusible soluble factors. While some of the apoptogenic isolates used two stimuli (direct contact with or without cytoadherence, plus soluble factors) to induce apoptosis, others used only one. Among the 16 apoptogenic isolates, eight specifically targeted brain endothelial cells, one lung endothelial cells, and seven both. These results indicate that the brain microvascular cell line was more susceptible to apoptosis triggered by P. falciparum than the primary pulmonary endothelial cells and may have relevance to host-parasite interaction.