The study was conducted at two regional referral hospitals, the Regional Hospital of Koudougou and the Regional Hospital of Banfora, respectively.
The Regional Hospital of Koudougou (lower transmission area, LMT) is located 100 km Centre West of the capital city of Ouagadougou. Malaria transmission in this central part of the country is markedly seasonal and intense during the rainy season from June to October. The entomological inoculation rate was estimated at 31.4 infective bites/person/year in a study conducted in the neighbouring zone of Saponé .
The Banfora Regional Hospital (higher transmission area, HMT) is located within a very highly endemic area where transmission occurs throughout the year, with a peak during the rainy season (from June to October). The entomological inoculation rates (EIR) ranges from 55 to 400 infected bites/person/year (Tiono et al, unpublished data).
In both areas, the main malaria vectors are Anopheles gambiae, An. arabiensis and An. funestus and P. falciparum is responsible for more than 90% of all clinical malaria cases [7, 8].
Recruitment and management of study participants
The recruitment of children took place from August 2017 to August 2018 with an interruption from April to June 2018 (representing the dry season). For all consecutive children presenting at the paediatric emergency room at any time with a clinical presentation suggestive of severe malaria, an informed consent was obtained by study personnel from parents/legal representatives. Patients were further assessed by paediatric ward clinicians (who benefited from a refresher protocol specific training prior to the study start) and observations recorded using a standardized case report form. Data collected included the medical history, vital signs, a complete physical examination for signs of severity (affecting the airway, respiratory, circulatory, and neurological systems). Finger prick blood sample was taken for malaria diagnosis (Rapid diagnosis test (SD Bioline Malaria Ag Pf® (Histidin Rich Protein 2, HRP2)) and malaria smear (Method for microscopy examination of blood smears and criteria for diagnosis of severe malaria are given below), haemoglobin and glucose measurements using point of care devices (HemoCue® Hb 201+ and HemoCue® Glucose 201+; HaemoCue AB, Ängelholm, Sweden). If the RDT was positive, antimalarial treatment was immediately initiated based on the National Malarial Control Programme (NMCP) guidelines.
Children received parenteral artesunate at 2.4 mg/kg body weight on admission (time zero), then after 12 and 24 hours and then once a day, or artemether Injection at 3.2 mg/kg on admission, then 1.6 mg/kg body weight per day. In both cases, parenteral administration continued until the child improved and was able to take full course of oral artemisinin-based combination therapy (ACT), artemether-lumefantrine or artesunate-amodiaquine. Supportive therapy recommended for severe malaria includes the treatment of hypoglycaemia with dextrose when glucose <2.2 mmol/l, blood transfusion for children with haemoglobin less than 5 g/dL. All treatments were free of charge. No adjusted dose of parenteral artesunate for children weighing less than 20 kg was adopted by the NMCP at the time of the study conduct.
Blood smears reading
Blood films were managed as described elsewhere . All RDT positive children had blood smears taken and examined by light microscopy. In brief, smears were air-dried and Giemsa-stained for examination by a light microscope fitted with 100 X oil immersion lens at a single laboratory. At least two hundred thick film fields were examined before a slide was declared negative. If Plasmodium asexual forms were found, a total of two hundred thick film fields were screened for Plasmodium species other than P. falciparum. If P. falciparum was present, a count of asexual forms against leukocytes was made using a tally counter. Counting was conducted based on at least two hundred leukocytes in consistence with WHO standards. If less than 10 parasites were identified from the two hundred leukocytes screened, the count was extended to 1,000 leukocytes. On the other hand, if P. falciparum gametocytes were seen, a gametocyte count was performed against 1,000 leukocytes. All slides were read by two independent microscopists with a third reading in case of discordant results. The final result was based on the two most concordant readings. All readers are certified competent/expert by an external quality assurance system with Clinical Laboratory Services (http://www.cls.co.za), South Africa.
Severe malaria case definitions
Severe malaria was defined based on presence of one or more criteria outlined in box 1 with a malaria positive RDT result. Only haemoglobin and glucose were measured in study participants. Therefore, it was not possible to assess the incidence of other clinical features as defined by the WHO; among others the hyperlactataemia, hyperbilirubinemia, metabolic acidosis, renal failure.
Passing dark urine was considered as a proxy of haemoglobinuria. As per country NMCP guidelines, we have also included in severe cases definitions children with incoercible vomiting, lethargy, and inability to drink or suck.
Data were entered into a MS ACCESS database and analysed using STATA software (Version 14.0, College Station, TX: StataCorp; 2015). Analysis included all paediatric admissions meeting the study eligibility criteria.
Ethical and regulatory approvals
The study protocol and associated documents were reviewed and approved by CNRFP institutional bioethics committee (approval reference N° 2015/007/MS/SG/CNRFP/CNRFP/CIB), the Ministry of Health Ethical Committee for Biomedical Research (approval reference N° 2015-7-092). All study participants’ parents or legal representatives gave documented informed consent before any study procedures were performed. The study was conducted according to the principles of the declaration of Helsinki and International Conference on Harmonization (ICH) Good Clinical Practice (GCP) guidelines.