title: Application of magnetic cytosmear for the estimation of Plasmodium falciparum gametocyte density and detection of asexual stages in asymptomatic children.
abstract: BACKGROUND
  Conventional malaria parasite detection methods, such as rapid diagnostic tests (RDT) and light microscopy (LM), are not sensitive enough to detect low level parasites and identification of gametocytes in the peripheral blood. A modified and sensitive laboratory prototype, Magnetic Deposition Microscopy (MDM) was developed to increase the detection of sub-microscopic parasitaemia and estimation of gametocytes density in asymptomatic school children.
  
  
  METHODS
  Blood samples were collected from 303 asymptomatic school children from seven villages in Bagamoyo district in Tanzania. Participants were screened for presence of malaria parasites in the field using RDT and MDM whereas further examination of malaria parasites was done in the laboratory by LM. LM and MDM readings were used to calculate densities and estimate prevalence of asexual and sexual stages of the parasite.
  
  
  RESULTS
  Plasmodium falciparum parasites (asexual and sexual stages) were detected in 23 (7.6 %), 52 (17.2 %), and 59 (19.5 %) out of 303 samples by LM, RDT and MDM respectively. Gametocytes were detected in 4 (1.3 %) and 12 (4.0 %) out of the same numbers of samples by LM, and MDM, respectively. Likewise, in vitro results conducted on two laboratory strains of P. falciparum, 3D7 and NF54 to assess MDM sensitivity on gametocytes detection and its application on concentrating gametocytes indicated that gametocytes were enriched by MDM by 10-fold higher than LM. Late stages of the parasite strains, 3D7 and NF54 were enriched by MDM by a factor of 20.5 and 35.6, respectively. MDM was more specific than LM and RDT by 87.5 % (95 %, CI 71.2-89.6 %) and 89.0 % (95 % CI 82.9-91.4) respectively. It was also found that MDM sensitivity was 62.5 % (95 % CI 49.5-71.8) when compared with RDT while with LM was 36.5 % (95 % CI 32.2-60.5).
  
  
  CONCLUSIONS
  These findings provide strong evidence that MDM enhanced detection of sub-microscopic P. falciparum infections and estimation of gametocyte density compared to current malaria diagnostic tools. In addition, MDM is superior to LM in detecting sub-microscopic gametocytaemia. Therefore, MDM is a potential tool for low-level parasitaemia identification and quantification with possible application in malaria transmission research.
authors.affiliation: Bagamoyo Branch, Biomedical Thematic group, Ifakara Health Institute, P.O. Box 54, Bagamoyo, Tanzania. dsumari@ihi.or.tz.|School of Life Sciences and Bioengineering, The Nelson Mandela African Institution for Science and Technology, P.O. Box 447, Arusha, Tanzania. dsumari@ihi.or.tz.
authors.forename: Deborah
authors.initials: D
authors.lastname: Sumari
authors.affiliation: The Centre for Global Health and Disease, Case Western Reserve University, Cleveland, OH, 44106-7286, USA. bxg43@case.edu.
authors.forename: Brian T
authors.initials: BT
authors.lastname: Grimberg
authors.affiliation: The Centre for Global Health and Disease, Case Western Reserve University, Cleveland, OH, 44106-7286, USA. drm20@case.edu.
authors.forename: D'Arbra
authors.initials: D
authors.lastname: Blankenship
authors.affiliation: National Institute for Medical Research, Amani Medical Research Centre, P.O. Box 81, Muheza, Tanzania. jpmugasa@gmail.com.
authors.forename: Joseph
authors.initials: J
authors.lastname: Mugasa
authors.affiliation: Muvek Laboratories, P. O. Box 105270, Dar Es Salaam, Tanzania. kefas@muvek.co.tz.
authors.forename: Kefas
authors.initials: K
authors.lastname: Mugittu
authors.affiliation: Department of Biomedical Engineering/ND20, Learner Research Institute, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH, 44195, USA. moorel@ccf.org.
authors.forename: Lee
authors.initials: L
authors.lastname: Moore
authors.affiliation: School of Life Sciences and Bioengineering, The Nelson Mandela African Institution for Science and Technology, P.O. Box 447, Arusha, Tanzania. psgwakisa@gmail.com.|Genome Science Centre and Department of Veterinary Microbiology and Parasitology, Sokoine University of Agriculture, P.O. Box 3019, Morogoro, Tanzania. psgwakisa@gmail.com.
authors.forename: Paul
authors.initials: P
authors.lastname: Gwakisa
authors.affiliation: Department of Biomedical Engineering/ND20, Learner Research Institute, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH, 44195, USA. zborowm@ccf.org.
authors.forename: Maciej
authors.initials: M
authors.lastname: Zborowski
mesh_terms: D000293:Adolescent; D058345:Asymptomatic Infections; D002648:Child; D003430:Cross-Sectional Studies; D006801:Humans; D016778:Malaria, Falciparum / Q000469:parasitology*; D008853:Microscopy / Q000379:methods*; D059208:Parasite Load / Q000379:methods*; D018512:Parasitemia / Q000469:parasitology; D010963:Plasmodium falciparum / Q000302:isolation & purification*; D012680:Sensitivity and Specificity; D013636:Tanzania