FIND and partners begin evaluation of rapid malaria tests
What makes this and other tragic stories noteworthy is that it underlines the critical role accurate and accessible
diagnosis plays in a person’s treatment. Different forms of malaria display a variety
of symptoms that can resemble other infections like meningitis, tuberculosis,
pneumonia or even, as was the case of Ebi Kimanani, influenza. In many
countries where there are infrequent or only rare cases of malaria, symptoms
will often be attributed to other ailments and the wrong diagnosis will be made.
Even in areas where malaria is endemic, the often fatal disease is diagnosed late,
or at not all.
The sooner malaria is diagnosed, the sooner the patient can be treated and
return to a normal life. Clinical signs alone can be misleading, and several factors
drive the need for accurate diagnosis:
the continued illness left undiagnosed and untreated when patients
are assumed to have malaria
the waste of resources associated with overuse of
expensive anti-malarial drugs
the risk of rising drug resistance from indiscrimante use of
anti-malarial drugs
Until recently, the disease was difficult to diagnose since a) the malaria parasites
are not always easy to detect in blood, b) microscopy requires laboratory
infrastructure, c) parasitemia does not mean you have the disease, and d)
an initially low parasite burden can rise quickly. Approximately 15 years
ago, rapid diagnostic tests (RDTs) for malaria were developed that detect
proteins (antigens) from the parasite in the blood of infected patients, permitting
parasite-based diagnosis to be extended beyond the reach of microscopy,
and from clinic to the village level. This has enabled health workers and
communities in remote areas to appropriately manage malaria-like fever for
the first time.
Typical African village: RDTs are ideal for remote villages with little health infrastructure
Despite the relative poverty of a vast majority of malaria sufferers, the low
cost of developing RDTs, which can detect malaria antigens in a fingerprick
blood sample, has led to their relatively wide use, and a profusion of companies
are now making rapid tests. There are more than 50 companies making more
than 150 individual RDT products. As a result, national malaria control programs
are now faced with the challenge of deciding which tests give the most
reliable results, especially in light of the fact that their sensitivity is affected
not only by inconsistency in production but also by exposure to heat and
moisture during shipping and storage. Geographic variability in the parasites
themselves also causes some of these tests to underperform.
A collaboration between WHO and FIND to develop quality assurance systems
for malaria diagnostics has led FIND to begin implementing an accelerated
three-step solution to introduce wellperforming malaria RDTs in national disease
control programs. This response is the outcome of extensive efforts
on the part of several agencies from around the world.
Rapid diagnostic testing for malaria being performed in a health clinic
FIND has joined WHO and other partners to establish urgently needed mechanisms
which can a) indicate which RDTs are manufactured with the quality and
performance needed by public health programs; b) determine whether individual
production lots of RDTs are performing up to expectations after being
shipped to countries but before they are used in remote field sites; and c)
provide technicians and health workers with the means not only to verify that
the RDTs they are using are still satisfactory but also to prepare and interpret
them accurately. Once their accuracy is assured, other matters concerning
RDT usage can be addressed, thus clearing the way for the revolutionary
potential these tests can have in the management of febrile disease in
malaria-endemic regions.
Over the past two years, a globally representative reference collection of blood samples from malaria patients,
collected by collaborating institutions across three continents, has been
established in order to evaluate RDTs being used in the field. Blood dilutions
have been carefully made to standardize the concentration of malaria parasites in
each sample. These materials have been characterized by polymerase chain reaction (PCR) to identify parasite
species and by ELISA to determine the concentration of parasite antigen in the
dilutions, by research institutions collaborating with FIND and WHO. Nucleic
acid sequencing of the relevant variable genes has been carried out. Rapid test
manufacturers that operate according to international quality standards (ISO
13485:2003) have been invited to submit their RDTs for evaluation using the
reference materials. Companies have enlisted more than 40 products for testing
to be based at U.S. CDC in Atlanta. All of the submitted RDTs will be tested
using the reference materials, and subjected
to heat-stability studies.
Subsets of the global panel are held at a number of regional laboratories supported
by WHO and FIND. These laboratories, currently located in Cambodia,
Ethiopia, and the Philippines, provide a service to national governments and
other agencies purchasing RDTs by testing individual production lots after
procurement and shipping. This allows malaria control programs to be sure
that only RDTs with adequate sensitivity are dispensed in the field.
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