Comparison of PCR and microscopy for the detection of asymptomatic malaria in a Plasmodium falciparum/vivaxendemic area in Thailand

Coleman, Sattabongkot Jetsumon, Promstaporm Sommai, Maneechai Nongnuj, Tippayachai Bousaraporn, Kengluecha Ampornpan, Rachapaew Nattawan, Zollner Gabriela, Miller Robert, Vaughan, Thimasarn Krongtong, Khuntirat Benjawan

Description

Objective The main objective of this study was to compare the performance of nested PCR with expert microscopy as a means of detecting Plasmodium parasites during active malaria surveillance in western Thailand. Methods The study was performed from May 2000 to April 2002 in the village of Kong Mong Tha, located in western Thailand. Plasmodium vivax (PV) and Plasmodium falciparum (PF) are the predominant parasite species in this village, followed by Plasmodium malariae (PM) and Plasmodium ovale (PO). Each month, fingerprick blood samples were taken from each participating individual and used to prepare thick and thin blood films and for PCR analysis. Results PCR was sensitive (96%) and specific (98%) for malaria at parasite densities ≥ 500/μl; however, only 18% (47/269) of P. falciparum - and 5% (20/390) of P. vivax -positive films had parasite densities this high. Performance of PCR decreased markedly at parasite densities <500/μl, with sensitivity of only 20% for P. falciparum and 24% for P. vivax at densities <100 parasites/μl. Conclusion Although PCR performance appeared poor when compared to microscopy, data indicated that the discrepancy between the two methods resulted from poor performance of microscopy at low parasite densities rather than poor performance of PCR. These data are not unusual when the diagnostic method being evaluated is more sensitive than the reference method. PCR appears to be a useful method for detecting Plasmodium parasites during active malaria surveillance in Thailand.

Informations

• Publié par: biomed
• Publié le: 01 janvier 2006
• Nombre de lectures: 4
• Langue: English

Extrait

Malaria Journal

BioMedCentral

Open Access Research Comparison of PCR and microscopy for the detection of asymptomatic malaria in aPlasmodium falciparum/vivaxendemic area in Thailand 1 11 Russell E Coleman*, Jetsumon Sattabongkot, Sommai Promstaporm, 1 11 Nongnuj Maneechai, Bousaraporn Tippayachai, Ampornpan Kengluecha, 1 11 Nattawan Rachapaew, Gabriela Zollner, Robert Scott Miller, 2 31 Jefferson A Vaughan, Krongtong Thimasarnand Benjawan Khuntirat

1 Address: Departmentsof Entomology and Immunology, U.S. Army Medical Component, Armed Forces Research Institute of Medical Sciences, 2 3 Bangkok, Thailand,University of North Dakota, Grand Forks, North Dakota, USA andMinistry of Public Health, Nonthaburi, Thailand Email: Russell E Coleman*  [e-mail]; Jetsumon Sattabongkot  [e-mail]; Sommai Promstaporm  [e-mail]; Nongnuj Maneechai  [e-mail]; Bousaraporn Tippayachai  [e-mail]; Ampornpan Kengluecha  [e-mail]; Nattawan Rachapaew  [e-mail]; Gabriela Zollner  [e-mail]; Robert Scott Miller  [e-mail]; Jefferson A Vaughan  [e-mail]; Krongtong Thimasarn  [e-mail]; Benjawan Khuntirat  [e-mail] * Corresponding author

Published: 14 December 2006Received: 25 September 2006 Accepted: 14 December 2006 Malaria Journal2006,5:121 doi:10.1186/1475-2875-5-121 This article is available from: http://www.malariajournal.com/content/5/1/121 © 2006 Coleman et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract Objective:The main objective of this study was to compare the performance of nested PCR with expert microscopy as a means of detectingPlasmodiumparasites during active malaria surveillance in western Thailand. Methods:The study was performed from May 2000 to April 2002 in the village of Kong Mong Tha, located in western Thailand.Plasmodium vivax(PV) andPlasmodium falciparum(PF) are the predominant parasite species in this village, followed byPlasmodium malariae(PM) andPlasmodium ovale(PO). Each month, fingerprick blood samples were taken from each participating individual and used to prepare thick and thin blood films and for PCR analysis. Results:PCR was sensitive (96%) and specific (98%) for malaria at parasite densities≥ 500/µl; however, only 18% (47/269) ofP. falciparum- and 5% (20/390) ofP. vivax-positive films had parasite densities this high. Performance of PCR decreased markedly at parasite densities <500/µl, with sensitivity of only 20% forP. falciparumand 24% forP. vivaxat densities <100 parasites/µl. Conclusion:Although PCR performance appeared poor when compared to microscopy, data indicated that the discrepancy between the two methods resulted from poor performance of microscopy at low parasite densities rather than poor performance of PCR. These data are not unusual when the diagnostic method being evaluated is more sensitive than the reference method. PCR appears to be a useful method for detectingPlasmodiumparasites during active malaria surveillance in Thailand.

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