@article {Van Bortele009674, author = {Wim Van Bortel and Joachim Mari{\"e}n and Bart K M Jacobs and Denis Sinzinkayo and Pierre Sinarinzi and Emmanuel Lampaert and Rob D{\textquoteright}hondt and Jean-Marie Mafuko and Anja De Weggheleire and Florian Vogt and Neil Alexander and William Wint and Peter Maes and Veerle Vanlerberghe and Corey Leclair}, title = {Long-lasting insecticidal nets provide protection against malaria for only a single year in Burundi, an African highland setting with marked malaria seasonality}, volume = {7}, number = {12}, elocation-id = {e009674}, year = {2022}, doi = {10.1136/bmjgh-2022-009674}, publisher = {BMJ Specialist Journals}, abstract = {Background Long-lasting insecticidal nets (LLINs) are one of the key interventions in the global fight against malaria. Since 2014, mass distribution campaigns of LLINs aim for universal access by all citizens of Burundi. In this context, we assess the impact of LLINs mass distribution campaigns on malaria incidence, focusing on the endemic highland health districts. We also explored the possible correlation between observed trends in malaria incidence with any variations in climate conditions.Methods Malaria cases for 2011{\textemdash}2019 were obtained from the National Health Information System. We developed a generalised additive model based on a time series of routinely collected data with malaria incidence as the response variable and timing of LLIN distribution as an explanatory variable to investigate the duration and magnitude of the LLIN effect on malaria incidence. We added a seasonal and continuous-time component as further explanatory variables, and health district as a random effect to account for random natural variation in malaria cases between districts.Results Malaria transmission in Burundian highlands was clearly seasonal and increased non-linearly over the study period. Further, a fast and steep decline of malaria incidence was noted during the first year after mass LLIN distribution (p\<0.0001). In years 2 and 3 after distribution, malaria cases started to rise again to levels higher than before the control intervention.Conclusion This study highlights that LLINs did reduce the incidence in the first year after a mass distribution campaign, but in the context of Burundi, LLINs lost their impact after only 1 year.Data are available on reasonable request. The analysis presented in this study is based on the malaria incidence between 2011 and 2019 using routinely collected surveillance data obtained from the National Health Information System. Data are aggregated at health district level. No information is available on severity nor gender.}, URL = {https://gh.bmj.com/content/7/12/e009674}, eprint = {https://gh.bmj.com/content/7/12/e009674.full.pdf}, journal = {BMJ Global Health} }