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.

Background: Early detection of hypertension is necessary to reduce the risk of cardiovascular events. The aim of our study was to determine the prevalence of hypertension in high school students from Libreville, the capital city of Gabon and to identify their associated factors. Methods: This was a cross-sectional and analytical study carried out on a population of students enrolled in two professional technical high schools in Libreville during the 2018-2019 school years. The collection of students was done randomly in the two establishments after parental consent and administrative authorizations. The sample size was calculated using the Daniel Sharwtz's formula. The parameters collected were anamnestic, socio-demographic and clinical. The National High Blood Pressure and European Cardiology Society 2017 classifications were used for the analysis of blood pressure in children and young adults respectively. Results: A total of 613 students with mean an age of 20.3±2.5 years were included. Sex ratio was 2.3. Prevalence of hypertension was 19.4% and the following factors were found to be independently associated with hypertension:

Introduction: Blastocystis sp. is an intestinal protozoan that is commonly reported, but whose clinical significance remains controversial. Clinical forms of this infection range from asymptomatic carriage to clinical signs, specifically gastrointestinal ones. There is a lack of data on the epidemiology of this protist in Gabon. This study was carried out to provide data on the frequency of Blastocystis sp. infection and its association with clinical signs and the haemoglobin rate. Methods: A cross-sectional study was conducted between September 2018 and November 2019. Stool samples were collected in five of the nine provinces of Gabon from children and adults. Sociodemographic and clinical data were recorded using a standardised pre-tested questionnaire. Haematological parameters and temperature were reported in a laboratory register. Parasitological diagnosis was performed using stool direct examination and a Merthiolate-Iodine-Formaldehyde (M.I.F) concentration to detect Blastocystis sp. Results: In total, 843 participants were interviewed and examined; 414 brought back stool samples. The frequency of Blastocystis sp. infection was 45.2% (n = 187/414), and it increased with age: from 20.0% in young children to 49.5% in adults (P = 0.0057). Being a male (P = 0.08) tended to be associated with Blastocystis sp. carriage. In the multivariate logistic regression, only males were associated with Blastocystis sp. infection and had a 4.3-fold higher risk of being infected than females did (adjusted odds ratio = 4.3; 95% CI = 1.2–15.6; P = 0.03). Diarrhoea, abdominal pain and colitis were observed in some patients with Blastocystis sp. monoinfection. No relation between Blastocystis sp. carriage and anaemia was found. Conclusion: The frequency of Blastocystis sp. infection was high. Males were more at risk of being infected. Blastocystis sp. could be used as indicator in the improvement of environmental sanitation and hygiene, coupled with improved housing. Additional investigations in a population with clinical symptoms should be performed.

Background: 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 between different parasite species. Intestinal protozoa and helminths could modulate anti-malarial immunity, for example, thereby potentially increasing or reducing susceptibility to malaria. Methods: 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 (STH) and protozoan parasites. Nested PCR was used to detect submicroscopic plasmodial infection in individuals with negative blood smears. Cytometric Bead Array was used to quatify interleukin (IL)-6, IL-10 and Tumor Necrosis Factor (TNF)-α in plasma of subjects with different parasitological profiles. Results: Median IL-6 and IL-10 levels and the median IL-10/TNF- α ration were all significantly higher among individuals with Plasmodium (P.) falciparum infection compared to other groups ( P ≤0.0001). The median TNF-α level and IL-10/IL-6 ratio were higher in subjects with STH ( 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=-0.37; 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 compared to uninfected children. The IL-10/TNF-α ratio was also higher in children aged 5-15 years and in adults harbouring blood-borne filariae compared to 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. Conclusion: 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 are associated with an enhanced IL-10 response. Immunity against malaria could differ according to age and carriage of other parasites.

Background 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 between different parasite species. Intestinal protozoa and helminths could modulate anti-malarial immunity, for example, thereby potentially increasing susceptibility to malaria.Methods 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 and Mansonella perstans, intestinal helminths (STH) and protozoan parasites. Nested PCR was used to detect submicroscopic plasmodial infection in individuals with negative blood smears. Cytometric Bead Array was used to quantify interleukin (IL)-6, IL-10 and Tumor Necrosis Factor (TNF)-α in plasma of subjects with different parasitological profiles i.e. malaria only, filariasis only, intestinal protozoan only, soil-transmitted helminths (STH) only, malaria/filariasis, malaria/STH, malaria/intestinal protozoa co-infections and in uninfected individuals/control group.Results Median IL-6 (124.5 [36.9–433.9] pg/mL) and IL-10 (224.5 [78.0–657.9] pg/mL) levels and the median IL-10/TNF-α (69.9 [12.5–140-7]) ratio were all significantly higher among individuals with Plasmodium falciparum infection compared to other groups (p < 0.0001). The median TNF-α level (6.5 [3.5–11.7] pg/mL) and IL-10/IL-6 ratio (3.6 [2.0–11.9]) were higher in subjects with STH (p = 0.09) and P. falciparum-intestinal protozoa co-infection (p = 0.04), respectively. IL-6 (rho=-0.37; p < 0.01) and IL-10 (rho=-0.37; p < 0.01) levels, and the IL-10/TNF-α ratio (rho=-0.36; p < 0.01) correlated negatively with age, independently of infectious status. 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 compared to uninfected children. The IL-10/TNF-α ratio was also higher in children aged 5–15 years and in adults harbouring blood-borne filariae compared to 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.Conclusions Asymptomatic malaria is associated with a strong polarization towards a regulatory immune response, reflected by high circulating levels of IL-10. Co-infections with P. falciparum and intestinal protozoa are associated with an enhanced IL-10 response. Immunity against malaria could differ according to age and carriage of other parasites.