title: Limitations of Rapid Diagnostic Testing in Patients with Suspected Malaria: A Diagnostic Accuracy Evaluation from Swaziland, a Low-Endemicity Country Aiming for Malaria Elimination.
abstract: The performance of Plasmodium falciparum-specific histidine-rich protein 2-based rapid diagnostic tests (RDTs) to evaluate suspected malaria in low-endemicity settings has not been well characterized.
  
  
  
  Using dried blood spot samples from patients with suspected malaria at 37 health facilities from 2012 to 2014 in the low-endemicity country of Swaziland, we investigated the diagnostic accuracy of histidine-rich protein 2-based RDTs using qualitative polymerase chain reaction (PCR) (nested PCR targeting the cytochrome b gene) and quantitative PCR as reference standards. To explore reasons for false-negative and/or false-positive results, we used pfhrp2/3-specific PCR and logistic regression analyses of potentially associated epidemiological factors.
  
  
  
  From 1353 patients, 93.0% of RDT-positive (n = 185) and 31.2% of RDT-negative samples (n = 340) were available and selected for testing. Compared with nested PCR, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of RDTs were 51.7%, 94.1%, 67.3%, and 89.1%, respectively. After exclusion of samples with parasite densities <100/μL, which accounted for 75.7% of false-negative results and 33.3% of PCR-detectable infections, the sensitivity, specificity, PPV, and NPV were 78.8%, 93.7%, 62.3%, and 97.1%. Deletions of pfhrp2 were not detected. False-positivity was more likely during the second year and was not associated with demographics, recent malaria, health facility testing characteristics, or potential DNA degradation.
  
  
  
  In the low-transmission setting of Swaziland, we demonstrated low sensitivity of RDT for malaria diagnosis, owing to an unexpectedly high proportion of low-density infection among symptomatic subjects. The PPV was also low, requiring further investigation. A more accurate point-of-care diagnostic may be needed to support malaria elimination efforts.
authors.affiliation: Emory University School of Medicine, Atlanta, Georgia, USA.
authors.forename: Nikhil
authors.initials: N
authors.lastname: Ranadive
authors.affiliation: National Malaria Control Programme, Ministry of Health, Manzini, Swaziland.
authors.forename: Simon
authors.initials: S
authors.lastname: Kunene
authors.affiliation: National Malaria Control Programme, Ministry of Health, Manzini, Swaziland.
authors.forename: Sarah
authors.initials: S
authors.lastname: Darteh
authors.affiliation: Clinton Health Access Initiative, Mbabane, Swaziland.
authors.forename: Nyasatu
authors.initials: N
authors.lastname: Ntshalintshali
authors.affiliation: National Malaria Control Programme, Ministry of Health, Manzini, Swaziland.
authors.forename: Nomcebo
authors.initials: N
authors.lastname: Nhlabathi
authors.affiliation: National Malaria Control Programme, Ministry of Health, Manzini, Swaziland.
authors.forename: Nomcebo
authors.initials: N
authors.lastname: Dlamini
authors.affiliation: National Malaria Control Programme, Ministry of Health, Manzini, Swaziland.
authors.forename: Stanley
authors.initials: S
authors.lastname: Chitundu
authors.affiliation: Clinton Health Access Initiative, Mbabane, Swaziland.
authors.forename: Manik
authors.initials: M
authors.lastname: Saini
authors.affiliation: Department of Medicine, University of California, San Francisco, CA, USA.
authors.forename: Maxwell
authors.initials: M
authors.lastname: Murphy
authors.affiliation: Clinton Health Access Initiative, Mbabane, Swaziland.
authors.forename: Adam
authors.initials: A
authors.lastname: Soble
authors.affiliation: Department of Medicine, University of California, San Francisco, CA, USA.
authors.forename: Alanna
authors.initials: A
authors.lastname: Schwartz
authors.affiliation: Department of Medicine, University of California, San Francisco, CA, USA.
authors.forename: Bryan
authors.initials: B
authors.lastname: Greenhouse
authors.affiliation: Malaria Elimination Initiative, Global Health Group, University of California San Francisco (UCSF), San Francisco, CA, USA.|Department of Pediatrics, Benioff Children's Hospital and University of California, San Francisco, CA, USA.|Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, USA.
authors.forename: Michelle S
authors.initials: MS
authors.lastname: Hsiang
mesh_terms: D002846:Chromatography, Affinity / Q000379:methods*; D003955:Diagnostic Tests, Routine / Q000379:methods*; D013541:Eswatini; D006801:Humans; D016778:Malaria, Falciparum / Q000175:diagnosis*; D010963:Plasmodium falciparum; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012680:Sensitivity and Specificity
keywords: Rapid Diagnostic Test; diagnostic accuracy; low transmission; malaria; subpatent infection