title: Plasmodium vivax Transmission in Africa.
abstract: Malaria in sub-Saharan Africa has historically been almost exclusively attributed to Plasmodium falciparum (Pf). Current diagnostic and surveillance systems in much of sub-Saharan Africa are not designed to identify or report non-Pf human malaria infections accurately, resulting in a dearth of routine epidemiological data about their significance. The high prevalence of Duffy negativity provided a rationale for excluding the possibility of Plasmodium vivax (Pv) transmission. However, review of varied evidence sources including traveller infections, community prevalence surveys, local clinical case reports, entomological and serological studies contradicts this viewpoint. Here, these data reports are weighted in a unified framework to reflect the strength of evidence of indigenous Pv transmission in terms of diagnostic specificity, size of individual reports and corroboration between evidence sources. Direct evidence was reported from 21 of the 47 malaria-endemic countries studied, while 42 countries were attributed with infections of visiting travellers. Overall, moderate to conclusive evidence of transmission was available from 18 countries, distributed across all parts of the continent. Approximately 86.6 million Duffy positive hosts were at risk of infection in Africa in 2015. Analysis of the mechanisms sustaining Pv transmission across this continent of low frequency of susceptible hosts found that reports of Pv prevalence were consistent with transmission being potentially limited to Duffy positive populations. Finally, reports of apparent Duffy-independent transmission are discussed. While Pv is evidently not a major malaria parasite across most of sub-Saharan Africa, the evidence presented here highlights its widespread low-level endemicity. An increased awareness of Pv as a potential malaria parasite, coupled with policy shifts towards species-specific diagnostics and reporting, will allow a robust assessment of the public health significance of Pv, as well as the other neglected non-Pf parasites, which are currently invisible to most public health authorities in Africa, but which can cause severe clinical illness and require specific control interventions.
authors.affiliation: Spatial Ecology and Epidemiology Group, Department of Zoology, University of Oxford, Oxford, United Kingdom.|Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America.
authors.forename: Rosalind E
authors.initials: RE
authors.lastname: Howes
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Indiana University, Bloomington, Indiana, United States of America.|Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Reiner
authors.affiliation: Spatial Ecology and Epidemiology Group, Department of Zoology, University of Oxford, Oxford, United Kingdom.
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Battle
authors.affiliation: Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.
authors.forename: Joshua
authors.initials: J
authors.lastname: Longbottom
authors.affiliation: Spatial Ecology and Epidemiology Group, Department of Zoology, University of Oxford, Oxford, United Kingdom.
authors.forename: Bonnie
authors.initials: B
authors.lastname: Mappin
authors.affiliation: Department of Geography and Environment, University of Southampton, Highfield, Southampton, United Kingdom.
authors.forename: Dariya
authors.initials: D
authors.lastname: Ordanovich
authors.affiliation: Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America.|Department of Geography and Environment, University of Southampton, Highfield, Southampton, United Kingdom.|Flowminder Foundation, Stockholm, Sweden.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Tatem
authors.affiliation: Malaria Centre, London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: Chris
authors.initials: C
authors.lastname: Drakeley
authors.affiliation: Spatial Ecology and Epidemiology Group, Department of Zoology, University of Oxford, Oxford, United Kingdom.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Gething
authors.affiliation: Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Zimmerman
authors.affiliation: Spatial Ecology and Epidemiology Group, Department of Zoology, University of Oxford, Oxford, United Kingdom.|Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America.|Sanaria Institute for Global Health and Tropical Medicine, Rockville, Maryland, United States of America.|Institute for Health Metrics and Evaluation, University of Washington, Seattle, United States of America.
authors.forename: David L
authors.initials: DL
authors.lastname: Smith
authors.affiliation: Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America.|Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.|Institute for Health Metrics and Evaluation, University of Washington, Seattle, United States of America.
authors.forename: Simon I
authors.initials: SI
authors.lastname: Hay
mesh_terms: D000349:Africa / Q000453:epidemiology; D018562:Disease Transmission, Infectious; D004375:Duffy Blood-Group System; D019353:Endemic Diseases; D006801:Humans; D016780:Malaria, Vivax / Q000453:epidemiology* / Q000635:transmission*
chemical_list: D004375:Duffy Blood-Group System