LAMP - a simple and highly sensitive molecular test for malaria
Visual reading of amplified microorganisms using LAMP
Malaria is typically diagnosed by identifying
parasites in a fingerprick blood sample using microscopy or by using
an immunochromatographic rapid diagnostic test that detects parasite antigens.
Both methods can perform well enough to direct standard malaria treatment
(though microscopy is significantly more cumbersome), but neither
is highly sensitive. Infections with fewer than 100 parasites per microliter of
blood can be difficult to detect. In some settings, particularly in the diagnosis
of complex cases referred to hospital, or in the case of pregnant women or
other special patient groups, or in the setting of clinical trials of drugs or vaccines,
more sensitive testing is needed to definitively rule out the presence of
parasites in the blood.
Highly sensitive molecular assays such as the polymerase chain reaction
(PCR) that can be used to amplify and detect small quantities of parasite DNA
have been developed for malaria, but are not in common use because of the cost
and complexity usually associated with testing by PCR. FIND has been working
with Eiken Chemical Company, Ltd. in Japan for the past 3 years to develop a
simple and highly sensitive molecular test for tuberculosis that it believes may be
able to replace microscopy for detection of that disease. The Eiken technology,
called LAMP (Loop-mediated isothermal AMPlification), allows rapid amplification
and detection of a target genetic sequence with minimal instrumentation
and simplified sample processing. Recently, FIND has moved to deploy that
same technology platform for the detection of malaria.
Proof of principle for LAMP detection of malaria was published last year in Clinical
Chemistry by Poon and colleagues (Clin Chem. 2006 Feb;52(2):303-6). FIND
and Eiken have recently teamed up with experts at the Hospital for Tropical
Diseases (HTD) in London to take these findings forward toward the development
of a reference molecular test for malaria that could be used in district
hospitals and regional laboratories. HTD is an internationally recognized institute
dedicated to the prevention, diagnosis and treatment of tropical diseases and
travel-related infections, and is the referral site for malaria care in London.
Under the agreement, a scientist from Eiken will join the HTD team in London
for the coming year to facilitate the research and development work there.
He will expect to return to London with a prototype assay completed. The goal
is to develop a highly sensitive molecular test that can detect and distinguish P.
falciparum from the other species of malaria directly from a fingerprick blood
sample with minimal sample handling.
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