title: National Malaria Prevalence in Cambodia: Microscopy Versus Polymerase Chain Reaction Estimates.
abstract: Accurate information regarding malaria prevalence at national level is required to design and assess malaria control/elimination efforts. Although many comparisons of microscopy and polymerase chain reaction (PCR)-based methods have been conducted, there is little published literature covering such comparisons in southeast Asia especially at the national level. Both microscopic examination and PCR detection were performed on blood films and dried blood spots samples collected from 8,067 individuals enrolled in a nationwide, stratified, multistage, cluster sampling malaria prevalence survey conducted in Cambodia in 2007. The overall malaria prevalence and prevalence rates of Plasmodium falciparum, Plasmodium vivax, and Plasmodium malariae infections estimated by microscopy (N = 8,067) were 2.74% (95% confidence interval [CI]: 2.39-3.12%), 1.81% (95% CI: 1.53-2.13%), 1.14% (95% CI: 0.92-1.40%), and 0.01% (95% CI: 0.003-0.07%), respectively. The overall malaria prevalence based on PCR detection (N = 7,718) was almost 2.5-fold higher (6.31%, 95% CI: 5.76-6.89%, P < 0.00001). This difference was significantly more pronounced for P. falciparum (4.40%, 95% CI: 3.95-4.90%, P < 0.00001) compared with P. vivax (1.89%, 95% CI: 1.60-2.22%, P < 0.001) and P. malariae infections (0.22%, 95% CI: 0.13-0.35%, P < 0.0001). The significant proportion of microscopy-negative but PCR-positive individuals (289/7,491, 3.85%) suggest microscopic examination frequently underestimated malaria infections and that active case detection based on microscopy may miss a significant reservoir of infection, especially in low-transmission settings.
authors.affiliation: National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia. School of Public Health, National Institute of Public Health, Phnom Penh, Cambodia. soleyl@cnm.gov.kh.
authors.forename: Dysoley
authors.initials: D
authors.lastname: Lek
authors.affiliation: Institut Pasteur in Cambodia, Phnom Penh, Cambodia.
authors.forename: Jean
authors.initials: J
authors.lastname: Popovici
authors.affiliation: Institut Pasteur in Cambodia, Phnom Penh, Cambodia. Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France. Institut Cochin, Institut National de la Santé et de la Recherche Médicale U1016 (INSERM U1016), Faculté de Médecine, Université Paris Descartes Sorbonne Paris Cité, Paris, France. Laboratoire de Parasitologie-Mycologie, Hôpital Cochin, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France.
authors.forename: Frederic
authors.initials: F
authors.lastname: Ariey
authors.affiliation: World Health Organization Lao People's Democratic Republic Office, Vientiane, Lao People's Democratic Republic.
authors.forename: Seshu Babu
authors.initials: SB
authors.lastname: Vinjamuri
authors.affiliation: London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: Sylvia
authors.initials: S
authors.lastname: Meek
authors.affiliation: London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: Jan
authors.initials: J
authors.lastname: Bruce
authors.affiliation: Service de Médecine Tropicale et Humanitaire, Hôpitaux Universitaires de Genève, Geneva, Switzerland. Mahidol Oxford Tropical Medicine Research Unit, Bangkok, Thailand.
authors.forename: Walter R J
authors.initials: WR
authors.lastname: Taylor
authors.affiliation: National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia.
authors.forename: Duong
authors.initials: D
authors.lastname: Socheat
authors.affiliation: Institut Pasteur in Cambodia, Phnom Penh, Cambodia.
authors.forename: Didier
authors.initials: D
authors.lastname: Menard
authors.affiliation: Naval Medical Research Unit 2 Detachment, Phnom Penh, Cambodia.
authors.forename: William O
authors.initials: WO
authors.lastname: Rogers
mesh_terms: D000293:Adolescent; D002160:Cambodia / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008288:Malaria / Q000175:diagnosis / Q000453:epidemiology*; D016778:Malaria, Falciparum / Q000175:diagnosis / Q000453:epidemiology; D016780:Malaria, Vivax / Q000175:diagnosis / Q000453:epidemiology; D008297:Male; D008853:Microscopy; D010963:Plasmodium falciparum; D010965:Plasmodium malariae; D010966:Plasmodium vivax; D016133:Polymerase Chain Reaction; D015995:Prevalence; D055815:Young Adult