Amidou Z. Ouedraogo

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 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 estimates of enterotoxigenic Escherichia coli (ETEC) and Shigella burden in developing countries are limited by the lack of rapid, accessible, and sensitive diagnostics and surveillance tools. We used a “Rapid LAMP based Diagnostic Test (RLDT)” to detect ETEC and Shigella in diarrheal and non-diarrheal stool samples from a 12-month longitudinal cohort of children under five years of age in a peri-urban area of Ouagadougou in Burkina Faso (West Africa). To allow comparison with the RLDT-Shigella results, conventional culture methods were used to identify Shigella strains in the stool samples. As conventional culture alone cannot detect ETEC cases, a subset of E. coli-like colonies was tested using conventional PCR to detect ETEC toxins genes. Of the 165 stool samples analyzed for ETEC, 24.9% were positive when using RLDT against 4.2% when using culture followed by PCR. ETEC toxin distribution when using RLDT was STp 17.6% (29/165), LT 11.5% (19/165), and STh 8.5% (14/165). Of the 263 specimens tested for Shigella, 44.8% were positive when using RLDT against 23.2% when using culture. The sensitivity and specificity of the RLDT compared to culture (followed by PCR for ETEC) were 93.44% and 69.8% for Shigella and 83.7% and 77.9% for ETEC, respectively. This study indicates that both Shigella and ETEC are substantially underdiagnosed when using conventional culture and highlights the potential contribution of the new RLDT method to improve enteric disease burden estimation and to guide future efforts to prevent and control bacterial enteric infection and disease.

Continuous monitoring of malaria epidemiology is needed in malaria-endemic settings to inform malaria control and elimination strategies. This study aimed to compare the malariometric indices between the under-fives and school-age children. We surveyed children aged 1.5 to 12 years for plasmodia carriage with the aim of including them in a longitudinal follow-up cohort. The survey took place from 7–11 September 2020 in a southwest area of Burkina Faso. Clinical and demographic data including malaria control measures were collected. A finger prick blood sample was taken for haemoglobin testing, and blood smears and dried blood spot preparation. The malariometric indices were calculated and compared between school-age children and those under the age of five. Multiple logistic regression was fitted to assess the association between malaria parasite carriage and age categories. Based on the PCR results, the parasite prevalence was 21.4% in the under-fives versus 44.2% in school-age children (p-value < 0.0001), with a pooled prevalence of 32.7% (CI = [28.8, 36.8]). The gametocyte prevalence was also significantly higher in school-age children (11.9%) compared to the under-fives (3.7%). Adjusted for covariates, school-age children were 2.9 times (IC = [2.0, 4.2]) more likely to carry the asexual parasite, compared to the under-fives. Malaria was moderate and stable endemic in this area and school-age children play a key role in the spread of the disease. The WHO conditional recommendation for intermittent preventive treatment of malaria in school-aged children living in malaria-endemic settings with moderate to high perennial or seasonal transmission should be implemented.