Lessons learnt from evaluation of malaria RDTs Qin Cheng Australian Army Malaria Institute
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Lessons learnt from evaluation of malaria RDTs
Qin Cheng Australian Army Malaria Institute
Product testing
Lot testing
Positive control
Quality RDTs to improve case management
Head to head comparison on: •Detection rate •False pos rate •Heat stability •Ease of use
Evaluate all lots: •Detection rate •Heat stability
Develop recombinant
proteins
Better RDTs on the market
RDTs
Many RDTs (>200 brands) available on the market
Large differences in performance reported
Heterogeneous nature of malaria transmission and epidemiology
Field comparative test of all RDTs at different settings not possible
Laboratory testing
G6PD test
Many tests available on the market including 2 RDTs
Different approaches with different limits of detection
Outcomes affected by environmental and host factors
> 160 G6PDd mutant variants in different populations
Necessary for head-to-head comparison
RDTs
Specimen Bank • Collection and preparations
o 27 cultured lines o 273 isolates: 200 & 2000/µL o 90 parasite negatives o Aliquot into small vials
• Characterisation o Quantify antigen level o Stability o Gene sequencing
• Maintenance o Replacement strategy
G6PD tests
Specimen Bank • Enzyme /indirect test? • G6PD in frozen samples?
Cryopreserved samples? • Collection and preparations
o Composition and numbers o Different variants, zygosity o Infected and uninfected
• Characterization o Quantify enzyme activity o Stability o Gene sequence
• Maintenance
RDTs
Product Testing (CDC) • 40-50 products/round • 1200 tests /product
o 840 tests against parasites o 366 tests against negatives
• Parameters and output • Frequency of test and retest • Database and transferability
G6PD tests
Product Testing • Laboratory and staff • Number of lots and
replicates • Number of samples to be
tested against • Parameters and output • Frequency of test and retest • Database and SOPs
RDTs G6PD tests
Lot testing labs • Location: close to end users
and easy to ship in and out • EQA
Initial test • Number of tests • Samples to be tested
Real time monitoring • Sufficient storage space • Recall system in place
lot testing labs: • RITM, the Philippines, • IPC, Cambodia • EHNRI, Ethiopia
Initial test • 4 isolates (2x 200/µL, 1x
2000/µL) & 10 negatives
Real time monitoring • Every 3 or 6 months
Lots tested (2007-2010) • Initial QC: 675 • Real time monitoring: 1693
Develop in parallel with test development Accompany each box of tests Durability: better than or same as the test Form and format
• Blood? • Recombinant protein? • Ease of use
RDTs
Disease threshold Antigen range at a set
parasitemia Genetic diversity of
antigens Mapping epitopes of MABs Stability of antigens in
storage Other factors influencing
RDT performance …
G6PD tests
Drug dose
Enzyme activity
Haemolysis Genetic mutations
Other factors
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?
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Provide test panels at early stage of test development Provide test results as feed back Encourage test optimisation Publish test results Set procurement criteria
Admin and coordination Sample collection Sample characterization Product testing staff and facility Lot testing staff and facility Data analysis Data dissemination Research User pay?
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