Overall study design and study area
This was a randomised, controlled, observer-blind trial conducted among pre-school and school-age children in the Saraya district of Kedougou region, southeast Senegal (Fig. 1). The characteristics of the study population and setting have been reported previously. [9] Briefly, Saraya is about 800km from Dakar, the capital city of Senegal, and has an estimated population of 61,756 (2019 population census). Over 70% of the population live more than 5 km from a health facility. Subsistence farming is the main occupation of Saraya residents. Malaria and helminths are endemic in the district. [10–13] This trial was conducted in collaboration with the national malaria control programme and NTD programme of the Senegal Ministry of Health and Social Action.
Community engagement
Community engagement meetings were organised prior to the commencement of the study to explain the nature of the study to the parents/caregivers of potentially eligible children. During these meetings, the study team explained the need for this study, using a simple picture to illustrate the co-administration of SMC and anthelminthic drugs, the study rationale and informed consent procedure, and the risks and benefits of allowing their children to participate in the study. After these meetings, research staff identified parents/caregivers of potential study participants to explain the study to them in more individual basis.
Recruitment and randomisation
Based on the findings of a population-based survey conducted across 18 villages in Saraya district in the preceding year, [7] six villages with highest prevalences of malaria, schistosomiasis and STH were identified. Next, a census of potentially eligible children in the identified villages was conducted. In these villages, male and female children aged 1–14 years were recruited into this study. The parents/caregivers provided written informed consent and children aged ≥ 12 years who gave positive assent to join the trial (in line with legal regulations in Senegal), and who had been resident in the study area for at least six months were enrolled into the study. Exclusion criteria included children with an acute illness at the time of drug administration; those known to be HIV positive and receiving cotrimoxazole prophylaxis; those who had received a dose of either sulphadoxine-pyrimethamine (SP), amodiaquine (AQ), albendazole (ALB) or praziquantel (PZQ) during the previous six months; or had a known allergy to any of SP, AQ, ALB or PZQ. Eligible children were randomised in blocks of 3, using a table of random numbers and stratified by age groups, into one of three groups in a ratio of 1:1:1 as follows: the first group, which served as a control arm, received Vitamin A and Zinc on Day 0, followed by SMC drugs (SPAQ) on Days 1–3; the second group received praziquantel and Vitamin A on Day 0, followed by SMC drugs on Days 1–3; and the third group received albendazole (ALB) and praziquantel (PZQ) on Day 0, followed by SMC drugs on Days 1–3.
Study procedures
One day before the planned start date of the study, written informed consent was obtained, and a pre-labelled stool collection cup was given to the parents/caregivers of eligible children. The parents/caregivers were encouraged to collect a stool sample from their children and to keep this safely for the research team to collect the following day. On the start day of the study (Day 0), research staff confirmed that the parents had provided informed consent and the older children assent, and administered a purpose-designed electronic questionnaire to the parents/caregivers. The questionnaire collected information on items such as socio-demographic status, health and residence characteristics, history of de-worming and malaria treatment. The height/length (cm) and weight (kg) of each child participant were measured and the anthropometric indices height-for-age, weight-for-age, weight-for-height, and body mass index, were calculated using the WHO AnthroPlus software (www.who.int/growthref/tools/en/). The global-positioning system (GPS) coordinates of each study participant’s household was measured with a hand-held GPS device.
Prior to the administration of the study drugs, a finger-prick blood sample was collected from each child for malaria microscopy, and a blood spot filter paper sample was collected for DNA extraction and PCR amplification for species determination. Freshly voided urine and stool samples were also collected from all study children. The administration of the study drugs to the children and their subsequent safety assessments are described below. A post-intervention survey was conducted five months after co-administration of the study medications to assess the effectiveness of the combined treatment approach. Blood, urine and stool samples were collected again from all study participants during the post-intervention survey.
Study drugs
The anthelminthic drugs used in this trial were the WHO-approved medications for MDA of schistosomiasis and STH control, namely PZQ and ALB, respectively. The SMC drugs given were SP and AQ (SPAQ). The SMC drugs were obtained from the SMC implementation unit of the Senegal Ministry of Health, and albendazole and praziquantel were obtained from the NTD control programme of the Senegal Ministry of Health. Vitamin A and Zinc supplements were used as control drugs, so that the children randomised to all study arms receive three drugs. Vitamin A and zinc supplements have not been shown to affect the primary and secondary outcomes of this study. [14, 15] Vitamin A was given as a liquid, oil-based preparation of retinyl palmitate acetate, obtained from UNICEF, Senegal office. The zinc preparation was a citrus-flavoured tablet containing 25 mg Zinc in the form of zinc sulfate and was procured from Biolectra Zink; Hermes Arzneimittel GmbH, Munich, Germany. The doses of SP and AQ, ALB, PZQ, Vitamin A and zinc supplement were based on the child’s age (Table 1).
Table 1
Doses of study medications
|
Children aged 12–59 months
|
Children aged 5–14 years
|
SP tablet (500mg + 25mg)
|
A full tablet as a single dose on the first day of the SMC cycle
|
Two tablets as a single dose on the first day of the SMC cycle
|
AQ tablet (153mg base)
|
A full tablet as a single daily dose for 3 consecutive days of the SMC cycle
|
Two tablets as a single daily dose for 3 consecutive days of the SMC cycle
|
|
Children aged 12–24 months
|
Children aged greater than 2 years and up to 14 years
|
ALB tablet (200 or 400 mg depending on age)
|
A half dose of albendazole 200mg
|
A single dose of albendazole 400mg
|
|
Children aged 1–14 years
|
|
PZQ tablet (600mg)
|
Praziquantel based on their body weight 40mg/kg
|
|
Vitamin A (200,000 IU)
|
Children aged 1–14 years
|
|
|
200,000 IU Vitamin A
|
|
Zinc (40 mg/kg)
|
Zinc supplement based on their body weight 40mg/kg
|
|
Study drug administration
The anthelminthic and SMC drugs were only available in tablet form. Hence, to facilitate administration, the tablets were crushed into granules, and a teaspoonful of granulated table sugar was added to the crushed drugs. The study drugs were administered to the children by a trained pharmacist in the presence of their parents/caregivers. The anthelminthics (PZQ and ALB) were administered to children randomised to receive them 24 hours before SMC drugs (SPAQ) were administered as part of the annual SMC campaign. A 10-minute interval separated the administration of albendazole and praziquantel in the study children randomised to receive these drugs. Parents were encouraged to provide their children with a carbohydrate-rich meal before the administration of the study drugs If a child vomited any of the study drugs, a 30-minute period was allowed before re-administration, but if vomiting occurred a second time, the treatment on that occasion was not considered part of the study. A simple, user-friendly recording tool was used to capture the drug administration for each child participant. The staff who conducted safety assessment for the study participants were separate from those who gave the study drugs. Children who started the treatment but could not be found at home after reasonable efforts were excluded from the study.
Safety assessment
Trained field workers visited all enrolled children daily at home starting from the evening of day 0 until 3 days after completion of the first cycle of SMC, using a purpose designed electronic diary card which recorded the presence of any side effects such as fever, vomiting, diarrhoea, etc. In addition, all study participants who presented to the outpatient or emergency departments of Saraya health centre or health posts in the study villages were evaluated for malaria and any serious adverse events (SAE) that might have been related to administration of the study drugs. Trained research assistants visited each child one month after the first round of SMC cycle to check that there had been no severe reactions to the previous treatment, and if this was not the case, gave the next round of treatment. When a possible drug related SAE was reported to the study staff, the case was investigated by a Local Safety Monitor who was an experienced physician based in Senegal. The Local Safety Monitor reported the findings to the Sponsor of the study. Data obtained from all inpatient records for study children admitted to the hospital for at least 24 hours within one month of SMC administration were evaluated for severity and a possible relationship to administration of the study drugs using standard criteria. [16]
Laboratory methods
Haemoglobin concentrations were measured using the HemoCue® Hb 801 photometer, and anaemia was defined as an Hb concentration < 11.0 g/dl 10-10.9g/dl as mild anaemia, 7-9.9 g/dl as moderate anaemia, and < 7g/dl as severe anaemia. [17] Thick and thin blood films were prepared following standard operational procedures. Blood films were examined microscopically following standard procedures [18]. Slides were considered positive when asexual forms and/or gametocytes of any Plasmodium species were observed. Two experienced microscopists read all slides independently. Malaria parasite density per µl of blood was determined by counting the number of parasites per 200 leukocytes and multiplying by an average value of white blood cell count, considered to be 8,000/ul. Parasitaemia was classified as low (≤ 500 parasite/µl of blood), moderate (501–5000 parasites/µl of blood) or high (> 5000 parasites/µl of blood). [19]
A freshly voided urine sample was collected from each study participant into a pre-labelled plastic container with a screw cap. The urine filtration test was used to quantify S. haemotobium, as described by Cheesbrough. [18] In addition, parallel testing for schistosome circulating cathodic antigens (CCA) in urine was performed[20]. Duplicate smears were prepared for each stool sample using a 41.7 mg Kato-Katz template. Each slide was allowed to clear for 30 minutes, and then examined by an experienced technician at 100 × total magnification within one hour of preparation to avoid missing hookworm eggs, and to determine the egg counts for S. mansoni and STH. The intensity of the helminth infection was categorized, as described by Cheesbrough. [18] Quality control was performed by re-examining at least 10% of randomly selected blood slides, urine filters and Kato-Katz smears by an experienced independent laboratory scientist. A multiplex PCR assay was used for simultaneous detection of mixed infections of helminths. [21, 22] Dried blood spots were analysed for malaria using PCR methods, as described by Rougemont et al. [23]
Merthiolate-iodine-formalin (MIF) technique for detection of intestinal protozoa
The traditional fixation method, MIF technique, [24] was used to further examine the stool samples. The 2×24 Copro-Duo Kit (RAL Diagnostics, France) was used to highlight protozoan cysts, schistosome eggs and unfertilized Ascaris eggs. Stool samples were added to cryotubes to which Mercurothiolate, Iodine and Formalin (MIF) solution (4 drops of Lugol in 15 microliters of MIF) was added. The samples were stored at + 4°C, smears prepared and examined for parasite eggs using 10x and 40x microscope objectives.
Study endpoints
The primary trial endpoint was safety, measured as the incidence of adverse events related to study medications during a 6-day follow-up period after randomisation to each treatment arm (starting from day 0 of administration of anthelminthic drugs to three days after completion of the first cycle of SMC drugs. Unsolicited adverse events were recorded during a 30-day passive surveillance period after each SMC cycle, and SAEs throughout the study period. The following secondary endpoints were assessed before and after co-administration of SMC with anthelminthic drugs (i.e. one month after completion of the last SMC cycle which corresponded to the end of malaria transmission season: i) the prevalence and intensity of Plasmodium spp infection ii) the prevalence and intensity of Plasmodium-helminth co-infection, iii) the prevalence and intensity of each of the four STHs (hookworm, A. lumbricoides, T. trichiura, and S. mansoni) infections; iv) the prevalence and intensity of S.haematobium infection, and v) the prevalence of anaemia and mean haemoglobin concentration.
Sample size determination
A minimum sample size of 188 children in each treatment group was calculated to provide a probability of 95% or higher of observing at least one severe adverse event in the SMC plus anthelminthic groups, if the true incidence of the severe adverse event was 5% or higher in each treatment group. Haemoglobin (Hb) concentration was also taken into account for calculating the sample size. Given that the mean Hb concentration in the SMC alone group in a previous study [25] was 10.5 g/dl, we assumed that a mean Hb concentration of 11.0 g/dl in the SMC plus anthelmintic groups, the standard deviation (SD) of the Hb concentration of 1.5 g/dl and the mean difference between the treatment groups would be 0.5 g/dl. To achieve a power of 90% at 95% statistical significance, a minimum of 189 children per treatment arm was needed. Allowing 10% loss to follow up, approximately 200 children were enrolled into each treatment arm.
Data management
Field data were collected using a purpose-designed electronic questionnaire by trained research assistants, and these were uploaded on a daily basis on REDCap® (https://www.project-redcap.org/). Laboratory data were managed using Laboratory Information Management System (LIMS). [26] The field and laboratory data were merged and harmonised, cleaned, and analysed with STATA® version 18.1 SE (Stata Corp., College Station, TX, USA).
Statistical analysis
Descriptive statistics such as frequencies and proportions were used to summarise the baseline parasitic parameters and socio-demographical characteristics of the study participants by trial arm. Data were analysed using an Intention-to-treat (ITT) approach. We compared the proportions of adverse events (AEs) and the incidence (average number per participant) of reported AEs between the trial arms using Fisher’s exact test and Wald test following Poisson regressions with robust standard errors, respectively. Logistic regressions with robust standard errors were also used to estimate odds ratios. Wald tests were used to assess the evidence of difference in post-randomisation odds between trial arms, after controlling for pre-randomisation occurrence and baseline characteristics (sex, age group, weight, and malaria and helminth infections’ occurrence). Effect modification between intervention period and trial arm was also investigated using the Wald test. We estimated and plotted the geometric means of the P.falciparum intensities at the pre- and post-intervention periods. A univariable Poisson regression with robust standard error and the Wald test were used to compare the pre-intervention parasites intensities across groups, whereas a multivariable Poisson regression including the pre-intervention parasites intensities as a covariate and the Wald test were used to compare the post-intervention parasites intensities.
Ethical considerations
Ethical approvals for the trial were obtained from the Research Ethics Committees of the London School of Hygiene & Tropical Medicine and the Comité National d’Ethique pour la Recherche en Santé (CNERS) in Senegal. The Participant Information Sheet (PIS) was translated into French and trained field assistants who were native speakers interpreted the consent information in a Senegalese language preferred by the parents/carer-givers. If the parent/carer-giver was not able to read and write in French, a literate adult witness was present throughout the whole consent process and signed and dated the consent form. For children aged ≥ 12 years, positive assent was obtained in addition to the parental consent. All study children were assigned a unique number, which was used as an identifier throughout the study. Participants’ data were securely stored in the dedicated study’s computer devices which were encrypted and password protected. All laboratory results and adverse event data were encoded in an electronic database and stored securely. Only authorised study personnel had access to the study data.