Contributors: Papua New Guinea Institute of Medical Research (PNG-IMR); The Walter and Eliza Hall Institute of Medical Research (WEHI); University of Melbourne; Institute of Tropical Medicine Antwerp (ITM); Malaria : parasites et hôtes - Malaria : parasites and hosts; Institut Pasteur Paris (IP); Hub Bioinformatique et Biostatistique - Bioinformatics and Biostatistics HUB; Institut Pasteur Paris (IP)-Université Paris Cité (UPCité); Case Western Reserve University Cleveland; Swiss Tropical and Public Health Institute Basel; Burnet Institute Melbourne, Victoria; The 2006 cohort was funded in part by National Institutes of Health (AI063135, AI-46919, and TW007872), the Swiss National Science Foundation (grant no. 31003A-112196), the Australian Agency for International Development (AusAID) and the National Health and Medical Research Council (Grant no. 516735). The 2008 cohort received funding support from the Cellex Foundation, Barcelona, Spain. The 2013 cohort was funded by National Institute of Allergy and Infectious Diseases through Southwest Pacific International Centre of Excellence in Malaria Research (grant U19 AI089686) and Bill and Melinda Gates Foundation through the TransEPI consortium. MOK is supported by an Australian Awards DFAT Scholarship through University of Melbourne. LJR was supported by NHMRC Early Career Research Fellowship (GNT1016443) to conduct the 2013 cohort and is currently supported by NHMRC Career Development Fellowship Level 2 (GNT1161627). The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.
نبذة مختصرة : International audience ; Introduction: As malaria transmission declines, understanding the differential impact of intensified control on Plasmodium falciparum relative to Plasmodium vivax and identifying key drivers of ongoing transmission is essential to guide future interventions.Methods: Three longitudinal child cohorts were conducted in Papua New Guinea before (2006/2007), during (2008) and after scale-up of control interventions (2013). In each cohort, children aged 1-5 years were actively monitored for infection and illness. Incidence of malaria episodes, molecular force of blood-stage infections (molFOB) and population-averaged prevalence of infections were compared across the cohorts to investigate the impact of intensified control in young children and the key risk factors for malaria infection and illness in 2013.Results: Between 2006 and 2008, P. falciparum infection prevalence, molFOB, and clinical malaria episodes reduced by 47%, 59% and 69%, respectively, and a further 49%, 29% and 75% from 2008 to 2013 (prevalence 41.6% to 22.1% to 11.2%; molFOB: 3.4 to 1.4 to 1.0 clones/child/year; clinical episodes incidence rate (IR) 2.6 to 0.8 to IR 0.2 episodes/child/year). P. vivax clinical episodes declined at rates comparable to P. falciparum between 2006, 2008 and 2013 (IR 2.5 to 1.1 to 0.2), while P. vivax molFOB (2006, 9.8; 2008, 12.1) and prevalence (2006, 59.6%; 2008, 65.0%) remained high in 2008. However, in 2013, P. vivax molFOB (1.2) and prevalence (19.7%) had also substantially declined. In 2013, 89% of P. falciparum and 93% of P. vivax infections were asymptomatic, 62% and 47%, respectively, were sub-microscopic. Area of residence was the major determinant of malaria infection and illness.Conclusion: Intensified vector control and routine case management had a differential impact on rates of P. falciparum and P. vivax infections but not clinical malaria episodes in young children. This suggests comparable reductions in new mosquito-derived infections but a delayed impact on P. vivax relapsing ...
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