Performance evaluation of different strategies based on microscopy techniques, rapid diagnostic test and molecular loop-mediated isothermal amplification assay for the diagnosis of imported malaria

E Charpentier; E Benichou; A Pagès; P Chauvin; J Fillaux; A Valentin; H Guegan; E Guemas; A-S Salabert; C Armengol; S Menard; S Cassaing; A Berry; X Iriart

doi:10.1016/j.cmi.2019.05.010

Performance evaluation of different strategies based on microscopy techniques, rapid diagnostic test and molecular loop-mediated isothermal amplification assay for the diagnosis of imported malaria

Clin Microbiol Infect. 2020 Jan;26(1):115-121. doi: 10.1016/j.cmi.2019.05.010. Epub 2019 May 31.

Authors

E Charpentier¹, E Benichou², A Pagès³, P Chauvin², J Fillaux², A Valentin², H Guegan², E Guemas², A-S Salabert⁴, C Armengol², S Menard⁵, S Cassaing², A Berry⁶, X Iriart⁷

Affiliations

¹ Department of Parasitology-Mycology, Toulouse University Hospital, Toulouse, France; Center for Pathophysiology Toulouse Purpan (CPTP), University of Toulouse, CNRS, INSERM, UPS, Toulouse, France. Electronic address: charpentier.e@chu-toulouse.fr.
² Department of Parasitology-Mycology, Toulouse University Hospital, Toulouse, France.
³ Department of Pharmacy, Toulouse University Hospital, Toulouse, France; UMR 1027, Inserm, UPS University of Toulouse III, Toulouse, France.
⁴ Department of Radiopharmacy, Toulouse University Hospital, Toulouse, France; ToNIC, Toulouse Neuroimaging Center, University of Toulouse, Inserm, UPS, Toulouse, France.
⁵ Center for Pathophysiology Toulouse Purpan (CPTP), University of Toulouse, CNRS, INSERM, UPS, Toulouse, France.
⁶ Department of Parasitology-Mycology, Toulouse University Hospital, Toulouse, France; Center for Pathophysiology Toulouse Purpan (CPTP), University of Toulouse, CNRS, INSERM, UPS, Toulouse, France.
⁷ Department of Parasitology-Mycology, Toulouse University Hospital, Toulouse, France; Center for Pathophysiology Toulouse Purpan (CPTP), University of Toulouse, CNRS, INSERM, UPS, Toulouse, France. Electronic address: iriart.x@chu-toulouse.fr.

PMID: 31158521
DOI: 10.1016/j.cmi.2019.05.010

Abstract

Objectives: Malaria is one of most common tropical diseases encountered in travellers and migrants. It requires an urgent and reliable diagnosis considering its potential severity. In this study, performance of five diagnostic assays were evaluated in a nonendemic region and compared prospectively to quantitative PCR (qPCR).

Methods: A prospective study was conducted at Toulouse Hospital from August 2017 to January 2018 and included all patients with initial Plasmodium screening. Thin and thick blood smears (TnS, TkS), quantitative buffy coat (QBC), rapid diagnostic tests (RDTs) and commercial loop-mediated isothermal amplification (LAMP) were independently performed on each blood sample and compared to our qPCR reference standard.

Results: The study encompassed 331 patients, mainly returning from Africa. qPCR detected 73 Plasmodium-positive samples (including 58 falciparum). Individually, LAMP had a 97.3% (71/73) sensitivity, far ahead of TnS (84.9%, 62/73), TkS (86.3%, 63/73), QBC (86.3%, 63/73) and RDT (86.3%, 63/73). RDT demonstrated a high sensitivity for falciparum (98.3%, 57/58) but missed all ovale, malariae and knowlesi infections. Specificity was excellent for all techniques (99.6-100%). The most sensitive diagnosis strategies were TnS + RDT (95.9%, 70/73), TnS + LAMP (97.3%, 71/73) and TnS + RDT + LAMP (100%, 73/73), about 10% higher than strategies using exclusively microscopy, TkS + TnS (87.7%, 64/73) or QBC + TnS (87.7%, 64/73). TnS remains necessary for Plasmodium species identification and quantification. Adding sequentially TnS only on LAMP-positive samples did not decrease TnS + LAMP strategy sensitivity.

Conclusions: In nonendemic countries, the currently recommended microscopy-based strategies seem unsatisfactory for malaria diagnosis considering RDT and LAMP performance, two rapid and sensitive assays that require limited training.

Keywords: Alethia; Diagnosis; LAMP; Loop-mediated isothermal amplification; Malaria; QBC; RDT; Rapid diagnostic test; Thick smear; Thin smear.

Publication types

Comparative Study
Evaluation Study

MeSH terms

Africa
Communicable Diseases, Imported / diagnosis*
Communicable Diseases, Imported / parasitology
France
Humans
Malaria / diagnosis*
Malaria / parasitology
Microscopy / methods
Microscopy / standards*
Molecular Diagnostic Techniques / methods
Molecular Diagnostic Techniques / standards*
Nucleic Acid Amplification Techniques / methods
Nucleic Acid Amplification Techniques / standards*
Plasmodium
Prospective Studies
Real-Time Polymerase Chain Reaction / standards
Sensitivity and Specificity
Temperature