Using positive control wells to confirm quality of rapid tests
Diagram illustrating how a positive control well checks for RDT quality
As mentioned above, rapid diagnostic
tests have been playing a valuable and growing role in providing parasitebased
diagnosis of malaria in areas where good quality microscopy cannot
be sustained. They can bring huge improvements in the early recognition
and management of both malarial and non-malarial fever by demonstrating
(or excluding) the presence of antigens specific for malaria parasites in host
(patient) blood. Parasite-based diagnosis of malaria is becoming increasingly
important as resistance of malaria parasites to less expensive drugs has
led to rising use of artemisinin-based combination therapy (ACT) and other
higher-cost drug combinations. In this article, we use the term ‘RDT’ to refer
specifically to antigen-detecting lateral flow (immunochromatographic) tests.
While RDT-based malaria diagnosis is applicable in a range of health management
conditions, their valuable role is when diagnosis is done in tropical and subtropical
(malaria-endemic) regions, away from major health centers. In these districts, transport, storage, re-supply,
and supervision are often limited and difficult. Health workers must consistently
provide an accurate diagnosis to guide the management of malarial and
non-malarial fevers that may be rapidly fatal. Therefore, it is essential that
malaria RDTs be sensitive and specific, simple to use, stable despite changes
in ambient temperatures during storage and transport, and retain their accuracy
for long periods.
For these reasons, it is indispensible that the quality of rapid diagnostic
tests for malaria can be checked and assured wherever they are being used,
especially in remote clinics or in the hands of village volunteers. Ensuring
that they are giving accurate results will save lives by guiding correct treatment.
Demonstrating accuracy gives health workers the assurance they
need for prescribing appropriate treatment. Lack of confidence in results is
a major impediment to current RDTbased programs.
FIND and WHO are working with research partners to develop stable, positive control
wells (PCWs) containing the major target antigens of commercially-available
RDTs. These wells can provide a simple, low-cost method to verify RDT performance
and guarantee quality-monitoring from manufacture to the end-user.
On April 9, 2008 FIND organized a meeting between product development partners
at the Hospital for Tropical Diseases (HTD) in London. During the meeting, a
license and technology agreement was signed with the South African, non-profit
National Bioproducts Institute (NBI), and the partners agreed the terms and conditions
for a development and supply agreement with ReaMetrix. Development of PCWs will be followed by large-scale
field trials, the results of which are anticipated in 2009.
Partners met at HTD to discuss positive controls wells development, manufacturing and distribution
processesfrom left to right: Audrey Albertini, Scientific Assistant for Malaria Diagnostics, FIND; John Bligh,
Department of Clinical Parasitology, HTD; Sridhar Ramanathan, Director of Manufacturing,
ReaMetrix; Martin Bubb, Head Biotechnology Division, NBI; Sheri Miraglia, CSO of ReaMetrix;
Mark Perkins, CSO of FIND; David Bell, Scientist Malaria Diagnostics, WHO/WPRO; Peter Chiodini,
Head of the Department of Clinical Parasitology, HTD; taking the picture Ranald Sutherland,
Technology and Business Development, FIND
FIND is working with WHO and the Roll Back Malaria Partnership
to develop consensus on methods for RDT quality assurance
in
malaria controlled programs so that the methods developed by
FIND and WHO can be integrated into national health
programs
in an effective and consistent way.
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