title: Performance evaluation of automated depolarization analysis for detecting clinically unsuspected malaria in endemic countries.
abstract: This prospective study evaluated the efficiency of automated depolarization analysis for recognition of unsuspected malaria by haemozoin detection during routine full blood count (FBC) screening of 676 randomly selected out-patients in a malaria hypoendemic area of Senegal. An additional 123 patients with clinically suspected malaria were studied for comparison. Of the 799 samples, 648 (81.1%) were categorized as malaria-negative, 83 (10.4%) as malaria-positive, and 68 as treated (early convalescence) or subclinical malaria (indirect evidence of infection). At a discrimination level of one or more atypical pigment-containing monocytes (PCM), negative and positive agreement was found to be 95.6% and 91.6% respectively for all malaria-negative and parasite-positive samples combined. Increasing the discriminator to two or more PCM events improved the overall agreement to 97.5%. Multivariate analysis showed that the only significant risk factor for the presence of PCM (odds ratio>200) was malaria infection. In the randomly selected group of 676 patients, 41 unsuspected cases of malaria infection were detected using the panel of reference diagnostic tests, and 37 (90.2%) of these had atypical PCM. The detection of clinically unrecognized malaria infection as part of a routine FBC procedure is a potentially useful extended application for laboratories in countries with endemic malaria.
authors.affiliation: Laboratoire de Biologie, Institut Pasteur de Dakar, 36 Avenue Pasteur, B.P. 220, Dakar, Senegal.
authors.forename: Jacques-Albert
authors.initials: JA
authors.lastname: Dromigny
authors.forename: Ronan
authors.initials: R
authors.lastname: Jambou
authors.forename: Colin Stephen
authors.initials: CS
authors.lastname: Scott
authors.forename: Jean-David
authors.initials: JD
authors.lastname: Perrier-Gros-Claude
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D019353:Endemic Diseases; D004804:Eosinophils; D005260:Female; D006420:Hemeproteins / Q000032:analysis; D006801:Humans; D007223:Infant; D016778:Malaria, Falciparum / Q000175:diagnosis* / Q000453:epidemiology / Q000503:physiopathology; D008297:Male; D008859:Microscopy, Polarization / Q000379:methods*; D008875:Middle Aged; D009000:Monocytes / Q000502:physiology; D010587:Phagocytosis / Q000502:physiology; D010860:Pigments, Biological / Q000032:analysis; D011446:Prospective Studies; D012307:Risk Factors; D012675:Senegal / Q000453:epidemiology; D017678:Sex Distribution
chemical_list: D006420:Hemeproteins; D010860:Pigments, Biological; C020753:hemozoin