title: Field deployment of loop-mediated isothermal amplification for centralized mass-screening of asymptomatic malaria in Zanzibar: a pre-elimination setting.
abstract: BACKGROUND
  Molecular tools for detection of low-density asymptomatic Plasmodium infections are needed in malaria elimination efforts. This study reports results from the hitherto largest implementation of loop-mediated isothermal amplification (LAMP) for centralized mass screening of asymptomatic malaria in Zanzibar.
  
  
  METHODS
  Healthy individuals present and willing to participate in randomly selected households in 60 villages throughout Zanzibar were screened for malaria by rapid diagnostic tests (RDT). In 50% of the study households, participants were asked to provide 60 μL of finger-prick blood for additional LAMP screening. LAMP was conducted in two centralized laboratories in Zanzibar, by trained technicians with limited or no previous experience of molecular methods. The LAMP assay was performed with Loopamp(TM) MALARIA Pan/Pf Detection Kit (Eiken Chemical Company, Japan). Samples positive for Plasmodium genus (Pan)-LAMP were re-tested using Plasmodium falciparum-specific LAMP kits.
  
  
  RESULTS
  Paired RDT and LAMP samples were available from 3983 individuals. The prevalence of asymptomatic malaria was 0.5% (CI 95% 0.1-0.8) and 1.6% (CI 95% 1.1-2.2) by RDT and Pan-LAMP, respectively. LAMP detected 3.4 (CI 95% 2.2-5.2) times more Plasmodium positive samples than RDT. DNA contamination was experienced, but solved by repetitive decontamination of all equipment and reagents.
  
  
  CONCLUSIONS
  LAMP is a simple and sensitive molecular tool, and has potential in active surveillance and mass-screening programmes for detection of low-density asymptomatic malaria in pre-elimination settings. However, in order to deploy LAMP more effectively in field settings, protocols may need to be adapted for processing larger numbers of samples. A higher throughput, affordable closed system would be ideal to avoid contamination.
authors.affiliation: Malaria Research, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Nobelsväg 16, 171 77, Stockholm, Sweden. ulrika.morris@ki.se.
authors.forename: Ulrika
authors.initials: U
authors.lastname: Morris
authors.affiliation: Zanzibar Malaria Elimination Programme (ZAMEP), Ministry of Health, Zanzibar, Tanzania. mwikha@hotmail.com.
authors.forename: Mwinyi
authors.initials: M
authors.lastname: Khamis
authors.affiliation: Malaria Research, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Nobelsväg 16, 171 77, Stockholm, Sweden. berit.schmidt@ki.se.
authors.forename: Berit
authors.initials: B
authors.lastname: Aydin-Schmidt
authors.affiliation: Zanzibar Malaria Elimination Programme (ZAMEP), Ministry of Health, Zanzibar, Tanzania.
authors.forename: Ali K
authors.initials: AK
authors.lastname: Abass
authors.affiliation: Zanzibar Malaria Elimination Programme (ZAMEP), Ministry of Health, Zanzibar, Tanzania. mmwinyi@hotmail.com.
authors.forename: Mwinyi I
authors.initials: MI
authors.lastname: Msellem
authors.affiliation: Zanzibar Malaria Elimination Programme (ZAMEP), Ministry of Health, Zanzibar, Tanzania. maida.nassor@gmail.com.
authors.forename: Majda H
authors.initials: MH
authors.lastname: Nassor
authors.affiliation: Foundation for Innovative New Diagnostics (FIND), Geneva, Switzerland. Iveth.Gonzalez@finddx.org.
authors.forename: Iveth J
authors.initials: IJ
authors.lastname: González
authors.affiliation: Malaria Research, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Nobelsväg 16, 171 77, Stockholm, Sweden. Andreas.Martensson@ki.se.|Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden. Andreas.Martensson@ki.se.|Centre for Clinical Research Sörmland, Uppsala University, Uppsala, Sweden. Andreas.Martensson@ki.se.
authors.forename: Andreas
authors.initials: A
authors.lastname: Mårtensson
authors.affiliation: Zanzibar Malaria Elimination Programme (ZAMEP), Ministry of Health, Zanzibar, Tanzania. busudi@gmail.com.
authors.forename: Abdullah S
authors.initials: AS
authors.lastname: Ali
authors.affiliation: Malaria Research, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Nobelsväg 16, 171 77, Stockholm, Sweden. anders.bjorkman@karolinska.se.
authors.forename: Anders
authors.initials: A
authors.lastname: Björkman
authors.affiliation: Malaria Research, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Nobelsväg 16, 171 77, Stockholm, Sweden. Jackie.Cook@lshtm.ac.uk.|London School of Hygiene and Tropical Medicine, London, UK. Jackie.Cook@lshtm.ac.uk.
authors.forename: Jackie
authors.initials: J
authors.lastname: Cook
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D058345:Asymptomatic Infections / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D003955:Diagnostic Tests, Routine / Q000379:methods*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016778:Malaria, Falciparum / Q000175:diagnosis* / Q000453:epidemiology; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D021141:Nucleic Acid Amplification Techniques; D010963:Plasmodium falciparum / Q000302:isolation & purification*; D015995:Prevalence; D013636:Tanzania / Q000453:epidemiology; D055815:Young Adult