Search

Background: Chronic carriage of intestinal parasitic infections (IPIs) can induce chronic inflammation and dysbiosis, which are risk factors for non-communicable diseases. The objective of this study was to determine the relationship between IPI carriage and inflammation in a population of volunteers living in Gabon., Methodology and Principal Findings: A cross-sectional study was conducted from September 2020 to November 2021 in asymptomatic volunteers aged 18 years old and over, residing in different areas of Gabon: Libreville (urban area) and Koula-Moutou and Bitam (rural areas). The detection of IPIs was carried out using four common microscopic techniques. C-reactive protein (CRP), and high-sensitivity C-reactive protein (hsCRP) were measured and levels were compared according to the presence or absence of IPI. Overall, 518 participants were included, 64.5% (n = 334) of whom resided in urban area and 35.5% (n = 184) in rural areas. The median age was 35 years (27; 46). The prevalence of asymptomatic IPIs was 29.9% (n = 155), with a significantly higher frequency in rural areas than in urban area (adjusted OR 6.6 (CI 3.2-13.8), p < 0.01). Protozoa were more frequent than soil-transmitted helminths (STHs) in both areas: 81.6% (n = 40) in urban area and 69.8% (n = 74) in rural areas. STHs were predominant in rural areas (48.1% vs 22.4% in urban area. In case of IPI, the median values of CRP (15 (13-15) mg/L vs 13.0 (11.1-14.9) mg/L) and hsCRP (4.2 (1.4-13.0) mg/L vs 2.2(0.4-6.1) mg/L) were higher (p<0.01). Elevated hsCRP and CRP were significantly more frequent in parasitized individuals (for hsCRP: 22.6%, n = 35; for CRP: 52.9%, n = 82); in particular among STH carriers (for hsCRP: 65.9%, n = 27, for CRP: 36.6%, n = 15) (p < 0.01)., Conclusions/significance: This first study showed that asymptomatic IPIs, particularly STH carriage are associated with high CRP and hsCRP levels. Further larger and longitudinal studies are needed to elucidate the global and specie-specific enteropathogens link with chronic inflammation., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Kono et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: The aim of this study was to determine performance indicators of thick blood smears of 50 µl (TBS-50), following the Standards for the Reporting of Diagnostic Accuracy Studies-Bayesian Latent Class Model (STARD-BLCM) guidelines. TBS-50 was compared with two common parasitological techniques-direct examination of 10 µl blood and a leukoconcentration of 5 ml-for the diagnosis of microfilaremic loiasis., Methods: The study population was recruited among patients of the Department of Parasitology-Mycology-Tropical Medicine over a period of 1 year. Age, sex, symptoms, and eosinophilia variables were recorded from laboratory registers and medical files. Direct examination of 10 µl of blood, TBS-50, and the leukoconcentration technique with 5 ml of blood were performed for each patient. The classical formula and BLCM were used to determine the diagnostic accuracy of the three techniques as well as the prevalence of microfilaremic loiasis. Three models were built within the framework of BLCM-the BLCM model I and alternative models II and III-for sensitivity analysis., Results: In total, 191 patients consented to be included. The direct blood examination and TBS-50 yielded comparable qualitative and quantitative results. Hence, they are reported together. The prevalence of Loa loa microfilaremia was 9.4% (95% CI 5.7-14.5; n = 18/191) with direct blood examination/TBS-50 and 12.6% [8.2-18.1] (n = 24/191) for leukoconcentration. Comparing TBS-50 with the leukoconcentration method using the classical formula, the sensitivity was 75.0% [53.3-90.2], specificity was 100.0% [97.8-100.0], the positive predictive value was 100.0% [81.5-100.0], and the negative predictive value was 96.5% [92.6-98.7]. The prevalence of microfilaremic loiasis was estimated at 9.7% [6.2-13.7] using BLCM model I. The outputs of BLCM model I showed sensitivity of 78.9% [65.3-90.3], specificity of 100.0% [99.3-100.0], a positive predictive value of 99.1% [87.2-100.0], and a negative predictive value of 93.0% [87.3-97.7] for direct blood examination/TBS-50., Conclusions: TBS-50 demonstrates low sensitivity relative to two other techniques. In one in five cases, the result will be falsely declared negative using these methods. However, this method can be deployed with limited funds., (© 2024. The Author(s).)

The objective of this study was to analyze the relationship between the frequency of artemisinin-based combination (ACT) drug resistance molecular markers and clinical forms of P. falciparum malaria and parasitemia. A cross-sectional study was carried out between January and April 2014 at the Operational Clinical Research Unit of Melen in febrile children aged 12 to 240 months with a Plasmodium sp. infection. A total of 3 mL of peripheral blood collected from an EDTA tube was used for leukocyte depletion. DNA mutation detection was performed by next generation sequencing (NGS). A total of 1075 patients were screened for malaria. Among them, 384 had a Plasmodium infection. P. falciparum mono-infection was found in 98.9% of the patients. Pfcrt -326T mutation was found in all isolates, while 37.9% had Pfmdr2 -484I mutant allele. The highest median parasite densities were found in patients infected by parasites carrying the CVIET haplotype of the Pfcrt gene. The different genetic profiles found here, and their variations according to clinical and biological signs of severe malaria, are additional arguments for the surveillance of P. falciparum strains.

Background: The level of blood filariasis parasitaemia as well as the frequency of and the relationship between cotrimoxazole prophylaxis (CTX-P), antiretroviral therapy (ART) intake and CD4 cell count among people living with human immunodeficiency virus (PLHIV) in rural areas of Gabon were being studied., Methods: Sociodemographic data and recent biological tests of PLHIV and HIV-negative participants were collected. Loa loa and Mansonella perstans microfilaria were detected by direct microscopy examination and leucoconcentration., Results: Overall, 209 HIV-positive and 148 HIV-negative subjects were enrolled. The overall prevalence of microfilaria was comparable between PLHIV (19.9% [n=41/206]) and HIV-negative participants (14.8% [n=22/148]) (p=0.2). The L. loa infection rate was comparable between HIV-positive (9.2%) and HIV-negative participants (6.8%) (p=0.2), while the M. perstans infection rate was 14-fold higher among PLHIV (p<0.01). L. loa parasitaemia was 6-fold lower in PLHIV receiving CTX-P (median 150 mf/mL [interquartile range {IQR} 125-350]) than in patients without (900 [550-2225]) (p<0.01). Among subjects with a CD4 cell count <200 cells/μL, the prevalence of M. perstans was 7-fold higher than that of L. loa (20.6% vs 2.9%)., Conclusions: This study suggests a similar exposure to L. loa infection of PLHIV and HIV-negative patients while M. perstans is more frequently found in HIV-positive individuals, notably those with a CD4 count <200 cells/μL., (© The Author(s) 2022. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene.)

Background: Patients with acute febrile illness need to be screened for malaria and coronavirus disease 2019 (COVID-19) in malaria-endemic areas to reduce malaria mortality rates and to prevent the transmission of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)., Objectives: To estimate the frequency of children and adolescents with COVID-19 and/or malaria among febrile patients attending for malaria diagnosis., Method: This cross-sectional study was conducted in a sentinel site for malaria surveillance during the SARS-CoV-2 pandemic (Omicron variant), from October 2021 to December 2021 in Gabon. All febrile patients were tested for malaria using microscopy. Severe acute respiratory syndrome coronavirus 2 was detected by real time polymerase chain reaction (RT-PCR) and rapid antigen tests developed by Sansure Biotech ® ., Results: A total of 135 patients were screened. Their median age was 6 (interquartile range [IQR]: 3-14) years. Malaria was confirmed for 49 (36.3%) patients, 29 (32.5%) children, 13 (59.0%) adolescents and 7 (29.2%) adults. The frequency of COVID-19 cases was 7.4% ( n = 10/135), and it was comparable between children ( n = 6; 6.7%), adolescents ( n = 2; 9.1%) and adults ( n = 2; 8.3%) ( p = 0.17). Malaria and COVID-19 co-infections were diagnosed in 3 (6.1%) patients from all the age groups. Participants with a co-infection had a higher median temperature, a higher median parasitaemia, and were mostly infected with non- falciparum malaria., Conclusion: COVID-19 cases and cases of malaria/COVID-19 co-infections were found in febrile children and adolescents. SARS-CoV-2 testing should be included in the screening of suspected malaria cases., Contribution: This study highlights the presence of malaria-COVID-19 coinfection among children and adolescents who should also be screened for both diseases, like for adults., Competing Interests: The authors declare that they have no financial or personal relationships that may have inappropriately influenced them in writing this article., (© 2022. The Authors.)

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., Competing Interests: The authors have declared that no competing interests exist.

This study aims at establishing specimens pooling approach for the detection of SARS-CoV-2 using the RT-PCR BGI and Sansure-Biotech kits used in Gabon. To validate this approach, 14 positive samples, stored at -20°C for three to five weeks were analyzed individually (as gold standard) and in pools of five, eight and ten in the same plate. We created 14 pools of 5, 8 and 10 samples using 40 μL from each of the selected positive samples mixed with 4, 7 and 9 confirmed negative counterparts in a total volume of 200 μL, 320 μL and 400 μL for the pools of 5, 8 and 10 respectively. Both individual and pooled samples testing was conducted according to the BGI and Sansure-Biotech RT-PCR protocols used at the Professor Daniel Gahouma Laboratory (PDGL). Furthermore, the pooling method was also tested by comparing results of 470 unselected samples tested in 94 pools and individually. Results of our experiment showed that using a BGI single positive sample with cycle threshold (Ct) value of 28.42, confirmed by individual testing, detection occurred in all the pools. On the contrary samples with Ct >31 were not detected in pools of 10 and for these samples (Ct value as high as 37.17) their detection was possible in pool of 8. Regarding the Sansure-Biotech kit, positive samples were detected in all the pool sizes tested, irrespective of their Ct values. The specificity of the pooling method was 100% for the BGI and Sansure-Biotech RT-PCR assays. The present study found an increase in the Ct values with pool size for the BGI and Sansure-Biotech assays. This trend was statistically significant (Pearson's r = 0.978; p = 0,022) using the BGI method where the mean Ct values were 24.04±1.1, 26.74±1.3, 27.91±1.1 and 28.32±1.1 for the individual, pool of 5, 8 and 10 respectively. The testing of the 470 samples showed that one of the 94 pools had a positive test similar to the individual test using the BGI and Sansure-Biotech kits. The saving of time and economizing test reagents by using the pooling method were demonstrated in this study. Ultimately, the pooling method could be used for the diagnosis of SARS-CoV-2 without modifying the accuracy of results in Gabon. We recommend a maximum pool size of 8 for the BGI kit. For the Sansure-Biotech kit, a maximum pool size of 10 can be used without affecting its accuracy compared to the individual testing., Competing Interests: The authors have declared that no competing interests exist.

Introduction: Intestinal parasites infections are endemic in Gabon. Nevertheless, they are rarely described in people living with HIV (PLHIV)., Objective: The frequency of intestinal parasite infection was estimated and compared between HIV-positive and HIV uninfected individuals in Gabon; factors associated with intestinal parasites were also analysed., Material and Methods: Using a cross-sectional study design sociodemographic data, life style habits, antiretroviral therapy, cotrimoxazole use and CD4 cell count were recorded.. Stool samples from participants living in Koulamoutou and Oyem were analysed using microscopy. Chi-squared or fisher's exact tests and logistic regression were performed., Results: Among participants (n=332), female gender was predominant (73.7%; n=135/183) and the median age was 45 [33-57] years old. Among 183 samples, 53.6% (n = 98/183) were infected by intestinal parasites. The proportion was higher (72.1%) in HIV negative participants compared to PLHIV (42.6%) (p <0.01). PLHIV were more frequently poly-infected. Infection was frequent in patients using external toilets and tap water (>70.0%)., Conclusion: Prevalence of intestinal parasites is higher in seronegative participants but polyparasitism is more frequent in PLHIV. Strategies are focused on HIV negative population, but this study shows the importance of sensitization for PLHIV to improve their quality of life., (© 2020 Lengongo JVK et al.)

Purpose: Artesunate-amodiaquine (AS-AQ) and artemether-lumefantrine (AL) have been widely used for the treatment of uncomplicated Plasmodium falciparum malaria since 2005 in Gabon. Since 2011, a rebound of malaria morbidity has been observed in this country, while no survey evaluating ACT efficacy was performed. During the same period, parasite resistance against artemisinin has been reported in Asia. The aim of this study was to assess the efficacy and tolerability of these two drugs in two sentinel sites of Gabon 10 years after their implementation., Methods: Children aged from 12 to 144 months with uncomplicated malaria were recruited at the Regional Hospital of Melen, Libreville and in the Urban Health Center of Franceville between March 2014 and September 2015. The therapeutic efficacy was evaluated according to the WHO 2008 protocol of 28-day follow-up and PCR-uncorrected/corrected treatment outcomes were assessed., Results: One hundred and eighty-five children (98 ASAQ and 89 AL) were followed up until day 28. The PCR-corrected ACPR was 98.9% for AS-AQ and 96.4% for AL. Late therapeutic failure rate was 3.6% and 1.1% for AL and AS-AQ, respectively (p = 0.2). Adverse events and serious adverse events were rarely observed with both treatments., Conclusion: AS-AQ and AL are still efficacious and well-tolerated for the treatment of uncomplicated malaria in Gabonese children.

Unfortunately two errors appeared in this article.

Unfortunately, the original article [1] contained some errors. The table title of Tables 4, 5, 6, 7 were interchanged by mistake and displayed incorrectly in the article. The correct table titles of Tables 4, 5, 6, 7 can be found below.

Background: Submicroscopic malaria infections contribute to malaria transmission. Describing the extent of the parasite reservoir is of importance. In people living with human immunodeficiency virus (HIV), the frequency of subpatent malaria infections is rarely reported. The aim of the present study was to determine the frequency of submicroscopic infections in people living with HIV in Gabon and its relationship with cotrimoxazole (CTX) use., Methods: A survey was conducted in two health care centres in rural areas (Koulamoutou and Oyem) and three in urban areas (Libreville) of Gabon from March 2015 to June 2016. Blood samples were collected from consenting people living with HIV with a negative blood smear. Information on CTX and antiretroviral therapy intake was recorded from the medical file of the patient and through an interview. For molecular analysis, the Plasmodium small subunit ribosomal RNA gene was amplified by nested polymerase chain reaction., Results: Submicroscopic infections were detected in 10.1% (n=12/119) of the people living with HIV, more frequently in those residing in rural areas (15.1%) compared with urban areas (2.1%) (p<0.01). The proportion of anaemic patients was 1.74-fold more frequent in malaria-infected patients, although not statistically significant. Submicroscopic infections frequency did not vary according to CTX intake (p=0.6)., Conclusions: The present pilot study highlights a non-negligible frequency of submicroscopic malaria infections in people living with HIV from rural areas, but no relationship with CTX intake was found.

Background: Malaria, filariasis, and intestinal parasitic infections (IPIs) are common and frequently overlap in developing countries. The prevalence and predictors of these infections were investigated in three different settlements (rural, semi-urban, and urban) of Gabon., Methods: During cross-sectional surveys performed from September 2013 to June 2014, 451 individuals were interviewed. In addition, blood and stool samples were analysed for the presence of Plasmodium, filarial roundworm, intestinal protozoan, and helminth infections., Results: Intestinal parasitic infections (61.1%), including intestinal protozoa (56.7%) and soil-transmitted helminths (STHs) (22.2%), predominated, whereas Plasmodium falciparum (18.8%), Loa loa (4.7%), and Mansonella perstans (1.1%) were less prevalent. Filariasis and STHs were mainly found in rural settlements, whereas a higher plasmodial infection prevalence rate was observed in the periurban area. The most common IPI was blastocystosis (48.6%), followed by ascaridiasis (13.7%), trichuriasis (11.8%), amoebiasis (9.3%), giardiasis (4.8%), and strongyloidiasis (3.7%). Hookworm was detected in one adult from rural Dienga. Adults had a higher prevalence of Blastocystis hominis and STHs, whereas Giardia duodenalis was more frequently observed among children aged below 5 years (P < 0.01). The polyparasitism rate was 41.5%, with 7.0% Plasmodium-IPIs and 1.8% Plasmodium-STH co-infections. The multivariate analysis showed that living in a suburban area, belonging to the age group of 5-15 years, having none or a secondary education, or having an open body water close to home were significant risk factors for malaria (P ≤ 0.01). For STH infections, identified risk factors were drinking untreated water and living in a rural area (P ≤ 0.04). No significant predictors were identified for IPIs and malaria-IPI co-infection., Conclusions: This study reports a high prevalence of IPIs and intestinal protozoa, but a low rate of malaria-IPI co-infections in the study sites. Improvements in the living conditions of the population such as adequate water supply and proper health education and sanitation should be integrated into control strategies for malaria, STHs, and IPIs.

We assessed Plasmodium (P.) falciparum allelic diversity based on clinical severity and age. The study was conducted from 2011 to 2012 in Libreville, Gabon where malaria prevalence was 24.5%. The polymorphism of the merozoite surface protein-1 (msp1) locus was analyzed in isolates from patients with complicated and uncomplicated malaria. Blood was collected on filter paper. After DNA extraction, genotyping of the msp1 gene was performed using nested PCR. The K1, Ro33, and Mad20 allelic families were detected in 71 (63%), 64 (57%), and 38 (34%) of the 112 analyzed samples, respectively. Overall, 17 K1 and 11 Mad20 alleles were detected. There was no association between msp1 allelic families and age. Mad20 allelic diversity increased with the severity of malaria. The number of K1 and Mad20 alleles decreased with age. The multiplicity of infection (MOI) was 1-6 genotypes and the complexity of infection (COI) 1.8 ± 1. The COI differed based on age: it was 1.9 (±1.1) in the isolates from adults, 1.8 (±1.1) in those from 0-5 year-old children, whereas it tended to be lower (1.6 ± 0.8) in those from 6-15 year-old children. Extensive genetic diversity is found in P. falciparum strains circulating in Libreville. The number of specific msp1 alleles increased with clinical severity, suggesting an association between the diversity and the severity of malaria., (© M.K. Bouyou-Akotet et al., published by EDP Sciences, 2015.)