title: Towards malaria microscopy at the point-of-contact: an assessment of the diagnostic performance of the Newton Nm1 microscope in Uganda.
abstract: Malaria microscopy in sub-Saharan Africa is often restricted by access to light microscopes. To address this gap, a novel portable inverted monocular microscope, the Newton Nm1, was designed and is now commercially available. Its diagnostic performance was assessed in a blinded-slide trial at ×1000 (oil) of Giemsa-stained thick blood films against a conventional microscope as undertaken by four Ugandan Ministry of Health technicians. With the Newton Nm1, diagnostic performance was: sensitivity 93.5% (95% confidence interval (CI) 78.6-99.2%), specificity 100.0% (95% CI 82.4-100.0%), positive predictive value 100.0% (95% CI 88.1-100.0%) and negative predictive value 90.5% (95% CI 69.6-98.8%). Discordance was due to a systematic error underestimating parasitaemia by ~45%; when counting Plasmodium parasites against 200 white blood cells, blood films with low parasitaemia (i.e. <100 μL(-1) of blood) could be overlooked and misclassified. By contrast, specificity was excellent with no false positives encountered. Whilst proven useful, especially in resource-poor environments, it is still unclear how we can ensure the uptake of the Newton Nm1 within sub-Saharan Africa.
authors.affiliation: Department of Parasitology,Liverpool School of Tropical Medicine,Liverpool L3 5QA,UK.
authors.forename: J Russell
authors.initials: JR
authors.lastname: Stothard
authors.affiliation: Vector Control Division,Ministry of Health,P.O. Box 1661, Kampala,Uganda.
authors.forename: Betty
authors.initials: B
authors.lastname: Nabatte
authors.affiliation: Department of Infectious and Tropical Diseases,London School of Hygiene and Tropical Medicine,Keppel Street, London WC1E 7HT,UK.
authors.forename: Jose C
authors.initials: JC
authors.lastname: Sousa-Figueiredo
authors.affiliation: Vector Control Division,Ministry of Health,P.O. Box 1661, Kampala,Uganda.
authors.forename: Narcis B
authors.initials: NB
authors.lastname: Kabatereine
mesh_terms: D006801:Humans; D008288:Malaria / Q000175:diagnosis* / Q000453:epidemiology; D008853:Microscopy / Q000295:instrumentation*; D015588:Observer Variation; D018512:Parasitemia; D010961:Plasmodium / Q000302:isolation & purification*; D011237:Predictive Value of Tests; D015995:Prevalence; D012680:Sensitivity and Specificity; D014454:Uganda / Q000453:epidemiology