Epidemiology of malaria in an area with pyrethroid-resistant vectors in south-western Burkina Faso: a pre-intervention study.

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.