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medRxiv preprint doi: https://doi.org/10.1101/2020.06.04.20120105; this version posted June 5, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC 4.0 International license . Epidemiology of malaria in an area with pyrethroid-resistant vectors in south-western Burkina Faso: a pre-intervention study. Anthony Somé1,2*, Issaka Zongo1, Bertin N’cho Tchiekoi3,5, Dieudonné D. Soma1,5, Barnabas Zogo3,5, Mamadou Ouattara4, Anyirékun F. Somé1, Amal Dahounto1,5, Alphonsine A. Koffi3, Cédric 3,5 1,5 1,6 1 Pennetier , Nicolas Moiroux , Seni Kouanda , and Roch K. Dabiré 1 Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso. 2 Université Saint Thomas d’Aquin (USTA), Ouagadougou, Burkina Faso. 3 Institut Pierre Richet (IPR), Bouaké, Côte d’Ivoire. 4 Centre de Recherche en Santé de Nouna (CRSN), Nouna, Burkina Faso. 5 Institut de Recherche pour le Développement - Maladies Infectieuses et Vecteurs Ecologie, Génétique, Evolution et Contrôle (IRD - MIVEGEC), Montpellier, France. 6 Institut Africain de Santé Publique (I.A.S.P.), Ouagadougou, Burkina Faso. *Corresponding author: Anthony Somé E-mail address: [email protected] Abstract Background: The objective of this study was to update malaria epidemiological profile prior to the implementation of a randomized controlled trial aiming to evaluate the efficacy of new vector control tools in complementary to the use of long-lasting insecticidal nets in Burkina Faso. Methods: We carried out active and passive cross-sectional surveys to estimate the prevalence and incidence of malaria infection from August 2016 to July 2017 in 27 villages of the Diebougou health district. Results: With the passive survey, we extracted data from 4814 patients included in the study from August 2016 to July 2017. Malaria incidence showed a seasonal distribution, with an overall incidence rate estimated at 414.3 per 1000 person-years. In the active cross sectional surveys, we enrolled 2839, 2594 and 2337 participants respectively in September 2016, December 2016 and June 2017. Prevalence of malaria infection were respectively 41.5%, 43.5% and 32.3% in September 2016, in December 2016 and June 2017. Multivariate analysis showed that girls seemed to have a lower risk of malaria infection (OR = 0.86; 95% CI = 0.79 - 0.95; p = 0.004). The risk of malaria infection was significantly lower in third survey (June 2017) at the beginning of the rainy season (OR = 0.69; 95% CI = 0.6 - 0.8; p < 0.001) compared to the first survey (September 2016) which was performed during the rainy season. Children aged 6 to 59 months had a higher risk of malaria infection compared to those aged 10 to 17 years (OR = 0.58; 95% CI = 0.51 - 0.66). Conclusion: Malaria burden remains high in this region of Burkina Faso despite substantial efforts made in malaria control during this current decade. Children under 5 years old were subject of malaria burden in this setting. This results reinforce the urgent need to develop alternative control strategies to complement those already existing. Key words Malaria, Morbidity, Vector control, Resistance, Burkina Faso. NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice. 1 medRxiv preprint doi: https://doi.org/10.1101/2020.06.04.20120105; this version posted June 5, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC 4.0 International license . Background Malaria remains a major cause of morbidity and mortality in sub-Saharan Africa, especially in children under the age of 5 [1]. In 2017, approximately 198 million malaria cases occurred globally worldwide, causing 584000 deaths. Most cases (90%) occurred in Africa, and most deaths (78%) were in children under 5 years old [2]. In Burkina Faso, malaria is the main cause of consultation, hospitalization and mortality in health centers especially within children under 5 years’ age and pregnant women. Indeed in 2017, 43.5% of consultations, 60.5% of hospitalizations and 35.9% of deaths in primary health centers (PHCs) in the country were due to malaria [3]. Many countries in the recent years have made significant progress in preventing malaria by largely focusing on vector control through LLINs and indoor residual spraying (IRS) of insecticides [4]. It is estimated that between 2000 and 2010, LLINs has saved more than 908000 lives, and since 2006, prevented three-quarters of deaths due to malaria [5]. However, the widespread use of LLINs leads to the development of vector resistance to insecticide. This insecticide resistance can reduce the effectiveness of these interventions and perhaps reverse progress in reducing malaria morbidity [6]. New strategies must be developed to reduce the development and spread of insecticide resistance and preserve the effectiveness of currently available insecticides and malaria control interventions. It is obvious that increasing the level of resistance corresponds to a decrease in the effectiveness of vector control strategies implementation [7]. As part of resistance management, the World Health Organization (WHO) recommends the development of alternative control strategies to complement those already existing and recognized for their effectiveness, but threatened by the expansion of resistance, in order to limit this expansion and maintain effectiveness [4]. The present study is part of a randomized controlled trial (RCT) in the framework of a project called REACT designed to investigate whether the combination of LLINs with other vector control strategies in areas with pyrethroid resistance can provide additional protection against malaria. Updated malaria epidemiology data in endemic areas are needed to serve as baseline to evaluate public health impact of alternative interventions implemented and to monitor effects of malaria control activities over time. We sought to describe the epidemiology of malaria prior to the conduct of the RCT. Specifically, in this paper, we assessed the incidence and prevalence of malaria during the rainy and dry seasons in Diebougou health district in the context of widespread insecticide resistance. Materials and methods Study area This study was part of a randomized controlled trial carried out in 27 villages in Diebougou health district from August 2016 to July 2017. These villages were selected based on geographical (distance between two villages higher than 2 km and accessibility during the rainy season) and demographic (a population size ranging from 200 to 500 inhabitants) criteria. The Diebougou health district is located in South-Western Burkina Faso, in the province of Bougouriba (Figure 1). With a total area of 2774 Km2, it covers five departments namely Diebougou, Tiankoura, Dolo, Iolonioro, and Bondigui and 154 villages. The district has fourteen PHCs and one district hospital. In 2016, the district served a total 135740 inhabitants comprised of 51.99% females. Most of its population is rural (85.42%) with 32% of children under five years [3]. The climate is a sub-Sudan type with a rainy season of six months from May to October and a dry season from November to April. The population is composed of several ethnic groups, the main ones being Djan, Dagara, Birifor, Lobi, Pougouli, Dogossè, Mossi and Fulani [8]. 2 medRxiv preprint doi: https://doi.org/10.1101/2020.06.04.20120105; this version posted June 5, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC 4.0 International license . Study population A census was carried out in august 2016 in each of these 27 villages. Houses were numbered, georeferenced, and information on the household’s residents (name, sex, age, level of education, profession and relationship with the household head) were collected. All inhabitants of the village were enrolled for passive cases detection while inclusion criteria in the active surveys were: age between 6 months and 17 years, residence in one of the target villages, provision of written informed consent or assent. Figure 1. Study area with the 27 target villages. Study design and procedure We combined fixed cross-sectional surveys directly in the selected villages and passive cases detection in primary health centers covering the selected villages. All surveys were completed over one year (August 2016 to July 2017). Passive malaria cases detection The passive detection was carried out in thirteen PHCs covering the twenty-seven villages and each village depended on a single primary health center. A dedicated study nurse visited each primary health center once every two months to review all outpatient and inpatient data in registers retrospectively. All the individuals residents in the selected villages and visiting these health centers were enrolled in the study. All consultants irrespective of conditions, age or sex were recorded. Variables recorded included the village where the subject came from, the age, sex, reason of visit (symptoms), temperature, diagnostic, rapid diagnostic test (RDT) for malaria done or not, RDT results (positive or negative or 3 medRxiv preprint doi: https://doi.org/10.1101/2020.06.04.20120105; this version posted June 5, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC 4.0 International license . undetermined), treatment prescribed. The diagnosis of malaria was based on the association of fever (or fever-related symptoms) with a positive RDT in all primary health centers.

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