title: Submicroscopic carriage of Plasmodium falciparum and Plasmodium vivax in a low endemic area in Ethiopia where no parasitaemia was detected by microscopy or rapid diagnostic test.
abstract: BACKGROUND
  Motivated by the success in malaria control that was documented over the last decade Ethiopia is aiming at malaria elimination by 2020 in selected districts. It is currently unknown if asymptomatic, submicroscopic malaria parasite carriage may form a hurdle to achieve elimination. The elimination effort may further be complicated by possible glucose-6 phosphate dehydrogenase (G6PD) deficiency which would hinder the use of 8-aminoquinolines in the elimination efforts.
  
  
  METHODS
  In February 2014 a community-based cross-sectional survey was conducted in Malo, southwest Ethiopia. Finger-prick blood samples (n = 555) were tested for presence of Plasmodium falciparum and Plasmodium vivax with microscopy, rapid diagnostic test (RDT), and nested polymerase chain reaction (nPCR). Multiplicity of P. falciparum infections was determined based on genotyping the polymorphic merozoite surface protein-2 (MSP-2) gene. Individuals were also genotyped for mutations in the gene that produces G6PD.
  
  
  RESULTS
  All study participants were malaria infection negative by microscopy and RDT. Nested PCR revealed P. falciparum mono-infection in 5.2% (29/555), P. vivax mono-infection in 4.3% (24/555) and mixed infection in 0.2% (1/555) of individuals. All parasitemic individuals were afebrile (axillary temperature <37.5°C). None of the study participants carried mutations for the G6PD African A-(202GA) and Mediterranean (563CT) variants. All infections, except one, were single-clone infection by MSP-2 genotyping.
  
  
  CONCLUSIONS
  The detection of a substantial number of subpatent malaria infections in an apparently asymptomatic population without evidence for malaria transmission by conventional diagnostics raises questions about the path to malaria elimination. It is currently unknown how important these infections are for sustaining malaria transmission in the study sites. The absence of G6PD deficiency indicates that 8-aminoquinolines may be safely deployed to accelerate elimination initiatives.
authors.affiliation: Department of Medical Microbiology, Radboud University Medical Centre, Geert Grooteplein 26-28, 6525GA, Nijmegen, The Netherlands. fitsum.tadesse@radboudumc.nl.|Medical Biotechnology Unit, Institute of Biotechnology, Addis Ababa University, POBox 1176, Addis Ababa, Ethiopia. fitsum.tadesse@radboudumc.nl.
authors.forename: Fitsum G
authors.initials: FG
authors.lastname: Tadesse
authors.affiliation: Department of Medical Microbiology, Radboud University Medical Centre, Geert Grooteplein 26-28, 6525GA, Nijmegen, The Netherlands. helmi.pett@radboudumc.nl.
authors.forename: Helmi
authors.initials: H
authors.lastname: Pett
authors.affiliation: Department of Medical Microbiology, Radboud University Medical Centre, Geert Grooteplein 26-28, 6525GA, Nijmegen, The Netherlands. amrish.baidjoe@gmail.com.
authors.forename: Amrish
authors.initials: A
authors.lastname: Baidjoe
authors.affiliation: Department of Medical Microbiology, Radboud University Medical Centre, Geert Grooteplein 26-28, 6525GA, Nijmegen, The Netherlands. kjerstin.lanke@radboudumc.nl.
authors.forename: Kjerstin
authors.initials: K
authors.lastname: Lanke
authors.affiliation: Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. lynn.grignard@lshtm.ac.uk.
authors.forename: Lynn
authors.initials: L
authors.lastname: Grignard
authors.affiliation: Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. colin.sutherland@lshtm.ac.uk.
authors.forename: Colin
authors.initials: C
authors.lastname: Sutherland
authors.affiliation: Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. tom.hall@lshtm.ac.uk.
authors.forename: Tom
authors.initials: T
authors.lastname: Hall
authors.affiliation: Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. chris.drakeley@lshtm.ac.uk.
authors.forename: Chris
authors.initials: C
authors.lastname: Drakeley
authors.affiliation: Department of Medical Microbiology, Radboud University Medical Centre, Geert Grooteplein 26-28, 6525GA, Nijmegen, The Netherlands. teun.bousema@radboudumc.nl.|Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. teun.bousema@radboudumc.nl.
authors.forename: Teun
authors.initials: T
authors.lastname: Bousema
authors.affiliation: Department of Microbial, Cellular and Molecular Biology, College of Natural Sciences, Addis Ababa University, POBox 1176, Addis Ababa, Ethiopia. binmamo@yahoo.com.
authors.forename: Hassen
authors.initials: H
authors.lastname: Mamo
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002353:Carrier State / Q000175:diagnosis / Q000453:epidemiology* / Q000469:parasitology; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005002:Ethiopia / Q000453:epidemiology; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D016778:Malaria, Falciparum / Q000175:diagnosis* / Q000453:epidemiology* / Q000469:parasitology; D016780:Malaria, Vivax / Q000175:diagnosis* / Q000453:epidemiology* / Q000469:parasitology; D008297:Male; D008853:Microscopy; D008875:Middle Aged; D018512:Parasitemia / Q000175:diagnosis / Q000453:epidemiology* / Q000469:parasitology; D010274:Parasitology; D010963:Plasmodium falciparum / Q000235:genetics; D010966:Plasmodium vivax / Q000235:genetics; D015995:Prevalence; D011933:Reagent Kits, Diagnostic; D055815:Young Adult
chemical_list: D011933:Reagent Kits, Diagnostic