title: Real-time PCR assay and rapid diagnostic tests for the diagnosis of clinically suspected malaria patients in Bangladesh.
abstract: BACKGROUND
  More than 95% of total malaria cases in Bangladesh are reported from the 13 high endemic districts. Plasmodium falciparum and Plasmodium vivax are the two most abundant malaria parasites in the country. To improve the detection and management of malaria patients, the National Malaria Control Programme (NMCP) has been using rapid diagnostic test (RDT) in the endemic areas. A study was conducted to establish a SYBR Green-based modified real-time PCR assay as a gold standard to evaluate the performance of four commercially-available malaria RDTs, along with the classical gold standard- microscopy.
  
  
  METHODS
  Blood samples were collected from 338 febrile patients referred for the diagnosis of malaria by the attending physician at MatirangaUpazila Health Complex (UHC) from May 2009 to August 2010. Paracheck RDT and microscopy were performed at the UHC. The blood samples were preserved in EDTA tubes. A SYBR Green-based real-time PCR assay was performed and evaluated. The performances of the remaining three RDTs (Falcivax, Onsite Pf and Onsite Pf/Pv) were also evaluated against microscopy and real-time PCR using the stored blood samples.
  
  
  RESULTS
  In total, 338 febrile patients were enrolled in the study. Malaria parasites were detected in 189 (55.9%) and 188 (55.6%) patients by microscopy and real-time PCR respectively. Among the RDTs, the highest sensitivity for the detection of P. falciparum (including mixed infection) was obtained by Paracheck [98.8%, 95% confidence interval (CI) 95.8-99.9] and Falcivax (97.6%, 95% CI 94.1-99.4) compared to microscopy and real-time PCR respectively. Paracheck and Onsite Pf/Pv gave the highest specificity (98.8%, 95% CI 95.7-99.9) compared to microscopy and Onsite Pf/Pv (98.8, 95% CI 95.8-99.9) compared to real-time PCR respectively for the detection of P. falciparum. On the other hand Falcivax and Onsite Pf/Pv had equal sensitivity (90.5%, 95% CI 69.6-98.8) and almost 100% specificity compared to microscopy for the detection of P. vivax. However, compared to real-time PCR assay RDTs and microscopy gave low sensitivity (76.9%, 95% CI 56.4-91) in detecting of P. vivax although a very high specificity was obtained (99-100%).
  
  
  CONCLUSIONS
  The results of this study suggest that the SYBR Green-based real-time PCR assay could be used as an alternative gold standard method in a reference setting. Commercially-available RDTs used in the study are quite sensitive and specific in detecting P. falciparum, although their sensitivity in detecting P. vivax was not satisfactory compared to the real-time PCR assay.
authors.affiliation: Parasitology Laboratory, ICDDR.B. GPO Box 128, Dhaka-1000, Bangladesh. shafiul@icddrb.org
authors.forename: Mohammad Shafiul
authors.initials: MS
authors.lastname: Alam
authors.forename: Abu Naser
authors.initials: AN
authors.lastname: Mohon
authors.forename: Shariar
authors.initials: S
authors.lastname: Mustafa
authors.forename: Wasif Ali
authors.initials: WA
authors.lastname: Khan
authors.forename: Nazrul
authors.initials: N
authors.lastname: Islam
authors.forename: Mohammad Jahirul
authors.initials: MJ
authors.lastname: Karim
authors.forename: Hamida
authors.initials: H
authors.lastname: Khanum
authors.forename: David J
authors.initials: DJ
authors.lastname: Sullivan
authors.forename: Rashidul
authors.initials: R
authors.lastname: Haque
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001459:Bangladesh; D002648:Child; D002675:Child, Preschool; D003955:Diagnostic Tests, Routine / Q000379:methods*; D005260:Female; D006801:Humans; D007223:Infant; D016778:Malaria, Falciparum / Q000175:diagnosis*; D016780:Malaria, Vivax / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D010963:Plasmodium falciparum / Q000235:genetics / Q000302:isolation & purification; D010966:Plasmodium vivax / Q000235:genetics / Q000302:isolation & purification; D016133:Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D013997:Time Factors; D055815:Young Adult