Open Forum Infectious Diseases
A Novel Testing Algorithm for Malaria • OFID • 1
Open Forum Infectious Diseases
®
Clinical Validation of a Commercial LAMP Test for
Ruling out Malaria in Returning Travelers: AProspective
DiagnosticTrial
JamesCheaveau,
1,2
HongNguyen,
1
BarbaraChow,
1
DewduneeMarasinghe,
3
Abu NaserMohon,
2,5
HongYuan,
4
GiseleViana,
5
Donellyvan Schalkwyk,
6
DeirdreChurch,
1,7,8
WilsonChan,
1,7
and Dylan R.Pillai
1,2,7,8
1
Clinical Section of Microbiology, Calgary Laboratory Services, Calgary, Alberta, Canada;
2
Department of Microbiology, Immunology, and Infectious Diseases, University of Calgary, Alberta, Canada;
3
Department of Epidemiology, Biostatistics, and Occupational Health, McGill University, Montreal, Quebec, Canada;
4
ProvLab Alberta, Edmonton, Alberta, Canada;
5
Laboratório de Pesquisas em
Malária, Instituto Evandro Chagas, Levilândia Ananindeua, Pará, Brasil;
6
Department of Immunology & Infection, Faculty of Infectious & Tropical Diseases, London School of Hygiene & Tropical
Medicine, London, UK;
7
Department Pathology and Laboratory Medicine, University of Calgary, Calgary, Alberta, Canada;
8
Department of Medicine, University of Calgary, Calgary, Alberta, Canada
e mainstay of malaria diagnosis relies on rapid diagnostic tests (RDTs) and microscopy, both of which lack analytical sensitivity.
is leads to repeat testing to rule out malaria. Aprospective diagnostic trial of the Meridian illumigene Malaria assay (loop-me-
diated isothermal amplication [LAMP]) was conducted comparing it with reference microscopy and RDTs (BinaxNOW Malaria)
in returning travelers between June 2017 and January 2018. Returning travelers with signs and symptoms of malaria were enrolled
in the study. RDTs, microscopy, and LAMP assays were performed simultaneously. Atotal of 298 patients (50.7% male; mean age,
32.5years) were enrolled, most visiting friends and relatives (43.3%), presenting with fever (88.9%), not taking prophylaxis (82.9%),
and treated as outpatients (84.1%). In the prospective arm (n=348), LAMP had a sensitivity of 98.1% (95% condence interval
[CI], 90.0%–100%) and a specicity of 97.6% (95% CI, 95.2%–99.1%) vs microscopy. Aer discrepant resolution with real-time
polymerase chain reaction, LAMP had a sensitivity of 100% (95% CI, 93.7%–100%) and a specicity of 100% (95% CI, 98.7%–100%)
vs microscopy. Aer discrepant resolution, RDTs had a sensitivity of 83.3% (95% CI, 58.6%–96.4%) and a specicity of 96.2% (95%
CI, 93.2%–98.1%) vs microscopy. When including retrospective specimens (n=377), LAMP had a sensitivity of 98.8% (95% CI,
93.2%–100%) and a specicity of 97.6% (95% CI, 95.2%–99.1%) vs microscopy, and aer discrepant resolution of this set, LAMP had
a sensitivity of 100% (95% CI, 95.8%–100%) and a specicity of 100% (95% CI, 98.7%–100%). Acost-benet analysis of reagents and
labor suggests savings of up to USD$13 per specimen using a novel algorithm with LAMP screening.
Keyw ords. malaria, LAMP, prospective study.
In 2016, there were approximately 216 million cases of malaria
in 91 countries, resulting in 445
000 deaths [1]. e World
Health Organization (WHO) African Region bears the larg-
est burden, with around 90% of the malaria cases. e WHO
guidelines recommend that all suspected cases of malaria be
conrmed with microscopy and/or rapid diagnostic tests. In
Canada, there are on average 488 malaria cases per year across
the country [2], and approximately 1700 annually in the United
States [3]. However, in nonendemic settings such as North
America, the vast majority of tests performed are negative.
Globally, the diagnosis of malaria is achieved with microscopy
and rapid diagnostic tests (RDTs), or a combination of these. e
WHO estimates that around 204 million patients were tested
by microscopy and 269 million rapid diagnostic tests were sold
in 2016 [4]. Although the increasing use of diagnostic-based
treatment rather than symptom-based treatment undoubtedly
has signicant benets, it is not without limitations. Microscopy
has been found to have a limit of detection (LOD) of 50–100
parasites/μL under eld conditions [5, 6]. However, this can
only be achieved when laboratory facilities are available, along
with a specialized microscopist. Studies have found that the
LOD varies depending on the training and experience of the
microscopist [7]. e method is labor-intensive and requires
constant quality assurance. Due to these limitations, and
therefore the possibility of false negatives, the Centers for
Disease Control and Prevention (CDC) in the United States and
Public Health Canada both recommend that 3 malaria slides
be taken [8, 9]. is is not just an inconvenience to the patient,
who may have to return the emergency room several times; it
results in increased health care costs due to re-attendance and
increased laboratorytime.
MAJOR ARTICLE
© The Author(s) 2018. Published by Oxford University Press on behalf of Infectious Diseases
Society of America. This is an Open Access article distributed under the terms of the Creative
Commons Attribution-NonCommercial-NoDerivs licence (http://creativecommons.org/licenses/
by-nc-nd/4.0/), which permits non-commercial reproduction and distribution of the work, in any
medium, provided the original work is not altered or transformed in any way, and that the work
is properly cited. For commercial re-use, please contact journals.permissions@oup.com
DOI: 10.1093/ofid/ofy260
Received 20 June 2018; editorial decision 5 October 2018; accepted 8 October 2018.
Correspondence: D. Pillai, MD, PhD, Departments of Pathology, Medicine, and MIID,
University of Calgary, 9-3535 Research Road NW, 1W-416, Calgary, AB, Canada, T2L2K8
(drpillai@ucalgary.ca).
; published online June 15, 2018
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