Alphonse Ouédraogo

Background: Intestinal parasitic infections are among the most common infections in humans and a major public health problem, affecting around 3.5 billion people, of whom about 450 million develop symptomatic illness and more than 200,000 die each year. Preschool- and school-age children bear much of this burden, and the impact falls disproportionately on people living in low- and middle-income countries (LMICs), where access to health care, safe drinking water and sanitation is limited. This study aimed to determine the prevalence of intestinal parasites, and its variation over time and with age, in children under five years of age in a peri-urban area of Ouagadougou, Burkina Faso, West Africa. Methods: We followed a community-based cohort of children under five years of age in a peri-urban area of Ouagadougou, with stool examinations at enrolment (M0, December 2020-March 2021) and at 6 (M6) and 12 months (M12). The cohort was established to estimate the incidence of shigellosis before a clinical evaluation of the oral shigella vaccine candidate in Burkina Faso. Fresh stool samples were examined by direct microscopy on the day of collection. Changes in prevalence across visits were analysed with generalised estimating equations to account for repeated measurements on the same children. Results: At enrolment, 38.04% (264/694) of children carried at least one intestinal parasite, and 60.1% (440/732) were positive at least once during follow-up. Predominant parasite was Giardia intestinalis, detected in 29.09% of the 1894 stool examinations. Other parasites included Entamoeba genus; Entamoeba histolytica, Hymenolepis nana, Endolimax nana and Isospora belli. Conclusions: Intestinal parasites, mainly Giardia intestinalis, were common in this peri-urban setting, with 33.05% of all stool examinations positive. §Persistence of these parasites across the three visits points denote a permanent reservoir of asymptomatic carriers that must be addressed to interrupt transmission. These results can guide interventions to reduce childhood morbidity and to improve the management of intestinal parasitic infections.

Background: Africa seemed to have had low SARS-CoV-2 infection and COVID-19 morbidity and mortality. While several studies reported high SARS-CoV-2 seropositivity among healthy Africans, others hypothesized that this could have resulted from pre-existing cross-reactive antibodies. Our study tracks trends in seropositivity across three West African countries during the Delta and Omicron pandemic waves using a validated test kit with 98.9% predictive accuracy, 97% sensitivity, and 99% specificity.Methods: Cross-sectional studies were conducted across three West African countries (Burkina Faso, Ghana, and Nigeria) with study sites conveniently selected in each country. Using the validated immunoassay kits, with already published validation procedures, SARS-CoV-2 antibodies were detected in peripheral blood during the ‘Delta’ and ‘Omicron’ waves. Participants' demographic and clinical data were obtained using a semi-structured questionnaire, and the primary outcome was the proportion of each population with SARS-CoV-2 antibodies.Findings: Across the 3 countries, 20,748 participants were recruited, and the results showed SARS-CoV-2 IgG seropositivity ranging between 24.1% to 77.0%, which increased during the Omicron wave. All sites showed low self-reported vaccination rates, delinking seropositivity and vaccination. While there was a significant positive association between seropositivity and age across all sites, the association with other demographic factors was country-dependent, and most participants expressed positive opinions of vaccination.Interpretation: This is one of the largest population-based SARS-CoV-2 seroepidemiology studies in Africa, confirming widespread mild SARS-CoV-2 infection in West Africa. This confirms a marked disconnect between high population exposure and low reported clinical burden, underscoring the need for strengthened community surveillance.

Background: The clinical research laboratory plays a pivotal role in the execution of clinical studies. The accurate and consistent registration of patients is dependent on the competent use of laboratory equipment and manual techniques by technicians, ensuring the reliability of the data collected. To support these activities, the Groupe de Recherche Action en Santé (GRAS) has been registered with the College of American Pathologists (CAP) and the Clinical Laboratories Services (CLS) in Johannesburg, South Africa, for external proficiency testing (EPT) of its laboratory, as part of our commitment to quality assurance. The following report details the performance achievements over the past five years. Methods: Proficiency testing (PT) samples are dispatched to GRAS Lab three times a year (quarterly) and the results are generally returned within two to three weeks. In the field of parasitology, challenge specimens were prepared as follows: thick and thin blood films were stained with Giemsa and mounted with strips to protect them for multiple uses. Photographs, also known as whole slide images (WSIs), were also taken. For the biochemistry and haematology tests, a set of five samples were received for processing. All evaluations were carried out in accordance with the GRAS laboratory’s internal procedures. Results: The CAP laboratory’s performance in terms of the diagnosis of malaria and other blood parasites from 2020 to 2024 was 97.3% accurate (ranging from 93.33% to 100%), with 93.33%, 100%, 100%, 93.33% and 100% achieved in 2020, 2021, 2022, 2023 and 2024, respectively. The number of microscopists evaluated annually has been subject to variation according to operational staff at the time of evaluation. A total of 31 microscopists were enrolled in the CLS PT scheme, of which 73.9% were classified as ‘experts’ and 19.2% as ‘reference’ microscopists. In the field of haematology, the PT demonstrated 100% accuracy over the four-year study period. This outcome is indicative of the high-performance levels exhibited by the automated systems under scrutiny and the comparable nature of the data produced by these systems. The same trend was observed in the biochemistry PT results, with an overall score of 92.12%, ranging from 78% to 100%. Conclusions: Proficiency testing has been shown to be an effective tool for quality assurance in laboratories, helping to ensure the accuracy of malaria and other blood parasite diagnoses made by microscopists, as well as the results generated by automated systems. It has been instrumental in assisting laboratories in identifying issues related to test design and performance.

Background/Objectives: Understanding the seroepidemiology of P. falciparum antibody responses is essential for assessing the acquisition of natural immunity and may guide interventions that impact the acquisition of immunity against malaria in endemic areas. This study assessed the association between antigen-specific IgG responses and protection against P. falciparum infection in children from Burkina Faso. Methods: Children aged 1.5 to 12 years were followed using cross-sectional and longitudinal approaches. IgG responses to 16 P. falciparum antigens were measured using a multiplex assay and analyzed by age group and malaria infection status. Associations between antibody levels and clinical malaria risk were assessed using incidence rate ratios (IRRs), and predictive performance of antibody combinations was evaluated using ROC analysis. Results: IgG responses to AMA1, CSP, and MSP2 CH150 showed weak but significant positive correlation with age. Children aged 5–12 years had higher antibody levels than younger children aged 1.5–5 years. Uninfected children had higher levels of antibodies to EBA181 RIII-V, Rh5.1, and SEA1, while infected children had elevated AMA1 and MSP2 CH150. Anti-GLURP R2 and anti-Rh5.1 antibodies were associated with reduced malaria risk (adjusted IRR = 0.52 and 0.40, respectively). The antibody combination of AMA1, GLURP R2, and Etramp5 Ag1 showed the best predictive performance (AUC = 0.70). Conclusions: This study underlines the value of less-studied antibodies (Etramp5 Ag1, Rh5.1, HSP40 Ag1) for diagnosing and protecting against malaria, opening up prospects for the development of more effective tests and targeted vaccine approaches. The variability of responses according to age and infection status calls for further studies to optimize prevention strategies.

Background: Clinical research lab is a key component of the conduct of clinical studies. Enrolment, follow up of patients is mainly based on the diagnosis skills of lab technicians and automates performance. To overcome this challenge, since 2020, as part of the quality assurance of its lab research activities, GRAS has registered with the College of American Pathologists (CAP) and the Clinical Laboratories Services (CLS) Johannesburg, South Africa for external proficiency testing (EPT) of its laboratory. The performances achieved during these last five years are reported. Methods: PT samples were couriered out three times a year (quadr-month) (hereafter referred to as Q) to GRAS Lab and results were generally due back two to three weeks later. For parasitology, challenges specimen are thick and thin blood films stained with Giemsa and mounted with strip to protected them for multiple use, or photographs also called ̎ whole slide images ̎ (WSI). For biochemistry and haematology, a set of 5 samples were received for processing. All the evaluations were performed according to the GRAS lab internal established procedures. Results: The overall CAP parasitological laboratory performance in term of diagnosis accuracy of malaria parasites and other blood parasites from 2020 to 2024 was 97.3% (ranging from 93,33 to 100%); with 93,33%, 100%, 100%, 93.33% and 100% achieved respectively in 2020, 2021, 2022, 2023 and 2024. Annually, the number of evaluated microscopists varied according to operational staff at the time of evaluation. In total, 31 microscopists were enrolled in CLS PT scheme, with 73.9% graded as “experts” microscopists and 19.2% graded as “reference” microscopists. For haematology, the PT showed 100% accuracy over the 4 years participation indicating the high-performance level of the tested automates and the comparability of data between automates. Same trend was observed for biochemistry PT results with an overall score of 92,12% ranging from 78% to 100%. Conclusion: The Proficiency testing has demonstrated value as an important laboratory quality assurance tool to guaranty the accuracy skill for malaria parasites and other blood parasites diagnosis by lab technicians and results generated by the automates. It has helped laboratories identify issues related to test design and performance.

Background In malaria vaccine clinical trials, immune responses after vaccination may be compromised due to immunosuppression caused by concurrent Plasmodium falciparum infection. This has a direct effect on the protective efficacy of the vaccine being evaluated. Therefore, parasite clearance prior to vaccination is being considered. Drugs with good safety and efficacy profiles and a short posttreatment prophylaxis period should be used. Two antimalarial drugs, artesunate (AS) as monotherapy and dihydroartemisinin-piperaquine (DHAPQ), have been evaluated in order to identify the most suitable option for use in future trials. Methods A cohort of children aged 1.5-12 years living in the Banfora Health District area was recruited. They were randomly assigned to receive supervised curative doses of AS monotherapy for 7 days or DHAPQ for 3 days. A polymerase chain reaction (PCR) was performed 21 days after treatment to confirm clearance of infection, and only those with a negative PCR were included in the study cohort for a 6-month longitudinal follow-up. Cohort children were actively visited fortnightly to collect blood samples for P. falciparum detection via microscopy and PCR. Passive surveillance was also conducted at the local health facility to record incident malaria episodes that occurred between two active visits. Results A total of 513 children were treated. Among these patients, 458 (89.3%) were free of P. falciparum malaria infection on day 21: 87.3% (226/259) in the AS group vs 91.3% (232/254) in the DHAPQ group (p = 0.053). The mean time to first malaria infection by microscopy was 154.9 (2.9) days in the DHAPQ arm and 129.0 (3.9) days in the AS arm (p < 0.01). The incidence rates of clinical malaria episodes during the follow-up period were 0.507 (0.369-0.645) and 0.293 (0.190-0.397) in the AS and DHAPQ arms, respectively (p < 0.05). Conclusions These findings suggest that although both drugs are effective in clearing P. falciparum infections, AS is likely to cause no more than minimal interference with the evaluation of vaccine efficacy endpoints and could, therefore, be considered for use. Trial registration: NCT04601714.

The aim of this study was to explore molecular measures of P. falciparum malaria burden (FOI and MOI) in the context of seasonal malaria chemoprevention. We analyzed malaria cases collected as part of a longitudinal cohort study. The cohort included P. falciparum-negative children aged 1.5 to 12, as confirmed by PCR 21 days after a radical cure using DHA-PQ or AS. Children were followed up for six months using active and passive case detection methods. At each visit, dried blood spots and blood smears were collected by finger prick, along with clinical data. Parasite DNA was extracted and analyzed by nested PCR for detection and genotyping of P. falciparum parasites. A total of 458 P. falciparum isolates collected during follow-up from October 2020 to March 2021 were genotyped. During the follow-up, children contracted 1.05 (95% IC [0.81–1.30]) new P. falciparum infections/child/time of exposure, and the MOI value was 3.00 (SD 1.60). Age is a protective factor (IRR: 0.74; 95% CI: 0.61, 0.90) against the occurrence of an episode of malaria, unlike an increase in MOI (IRR: 1.63; 95% CI: 1.04, 1.99), which is a favorable factor (p < 0.05). This study confirms the reduction in malaria transmission in our study area, probably due to the massive deployment of control tools.

Primaquine (PQ) has activity against mature P. falciparum gametocytes and proven transmission blocking efficacy (TBE) between humans and mosquitoes. WHO formerly recommended a single transmission blocking dose of 0.75 mg/kg but this was little used. Then in 2012, faced with the emergence of artemisinin-resistant P. falciparum (ARPf) in SE Asia, the WHO recommended a lower dose of 0.25 mg/kg to be added to artemisinin-based combination therapy in falciparum-infected patients in low transmission areas. This dose was considered safe in glucose-6-phosphate dehydrogenase deficiency (G6PDd) and not requiring G6PD testing. Subsequent single low-dose primaquine (SLDPQ) studies have demonstrated safety in different G6PD variants. Dosing remains challenging in children under the age of 5 because of the paucity of PQ pharmacokinetic (PK) data. We plan to assess the anti-infectivity efficacy of SLDPQ using an allometrically scaled, weight-based regimen, with a target dose of 0.25 mg/kg, in children with acute uncomplicated falciparum malaria. This study is an open label, randomised 1:1, phase IIb study to assess TBE, tolerability, pharmacokinetics and acceptability of artesunate pyronaridine (ASPYR) administered alone or combined with SLDPQ in 56 Burkinabe children aged ≥ 6 months– < 5 years, with uncomplicated P. falciparum and a haemoglobin (Hb) concentration of ≥ 5 g/dL. We will assess TBE, using direct membrane feeding assays (DMFA), and further investigate PQ pharmacokinetics, adverse events, Hb dynamics, G6PD, sickle cells, thalassaemia and cytochrome 2D6 (CYP2D6) status, acceptability of flavoured PQ [CAST—ClinSearch Acceptability Score Test®], and the population’s knowledge, attitude and practices on malaria. We expect children to accept tablets, confirm the TBE and gametocytocidal effects of SLDPQ and then construct a PK infectivity model (including age, sex, baseline Hb, G6PD and CYP2D6 status) to define the dose response TBE relationship that may lead to fine tuning our SLDPQ regimen. Our study will complement others that have examined factors associated with Hb dynamics and PQ PK. It will provide much needed, high-quality evidence of SLDPQ in sick African children and provide reassurance that SLDPQ should be used as a strategy against emerging ARPf in Africa. ISRCTN16297951. Registered on September 26, 2021