Open Peer Review Any reports and responses or comments on the article can be found at the end of the article. RESEARCH ARTICLE Gametocyte carriage in an era of changing malaria epidemiology: A 19-year analysis of a malaria longitudinal cohort [version 1; peer review: awaiting peer review] Michelle K. Muthui , Polycarp Mogeni , Kennedy Mwai , Christopher Nyundo , Alex Macharia , Thomas N. Williams , George Nyangweso , Juliana Wambua , Daniel Mwanga , Kevin Marsh , Philip Bejon , Melissa C. Kapulu 1,5 Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya African Health Research Institute, Durban, Congella, 4013, Private bag X7, South Africa Epidemiology and Biostatistics Division, School of Public Health, University of the Witwatersrand, Johannesburg, Parktown, 2193, 27 St Andrews Road, South Africa Department of Medicine, Imperial College London, St Mary's Campus, London, W21NY, UK Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7FZ, UK Abstract Interventions to block malaria transmission from humans to Background: mosquitoes are currently in development. To be successfully implemented, key populations need to be identified where the use of these transmission-blocking and/or reducing strategies will have greatest impact. We used data from a longitudinally monitored cohort of children from Methods: Kilifi county located along the Kenyan coast collected between 1998-2016 to describe the distribution and prevalence of gametocytaemia in relation to transmission intensity, time and age. Data from 2,223 children accounting for 9,134 person-years of follow-up assessed during cross-sectional surveys for asexual parasites and gametocytes were used in logistic regression models to identify factors predictive of gametocyte carriage in this cohort. Our analysis showed that children 1-5 years of age were more likely Results: to carry microscopically detectable gametocytes than their older counterparts. Carrying asexual parasites and recent episodes of clinical malaria were also strong predictors of gametocyte carriage. The prevalence of asexual parasites and of gametocyte carriage declined over time, and after 2006, when artemisinin combination therapy (ACT) was introduced, recent episodes of clinical malaria ceased to be a predictor of gametocyte carriage. Gametocyte carriage in children in Kilifi has fallen over time. Conclusions: Previous episodes of clinical malaria may contribute to the development of carriage, but this appears to be mitigated by the use of ACTs highlighting the impact that gametocidal antimalarials can have in reducing the overall prevalence of gametocytaemia when targeted on acute febrile illness. 1 1,2 1,3 1 1 1,4 1 1 1 1,5 1,5 1,5 1 2 3 4 5 Referee Status: AWAITING PEER REVIEW 05 Apr 2019, :66 ( First published: 4 ) https://doi.org/10.12688/wellcomeopenres.15186.1 05 Apr 2019, :66 ( Latest published: 4 ) https://doi.org/10.12688/wellcomeopenres.15186.1 v1 Page 1 of 21 Wellcome Open Research 2019, 4:66 Last updated: 13 APR 2019