In endemic regions, malaria is generally diagnosed using malaria rapid diagnostic tests (RDTs). These tests, which are affordable and easy to use in remote areas, are based on the detection in blood of two P. falciparum antigens: histidine-rich protein 2 (HRP2) and Plasmodium lactate dehydrogenase (pLDH).
The ability to evaluate RDT performance reliably and accurately using an internationally recognized reference Standard is critical. International Standards (IS) enable product comparison and procurement decisions, guide local quality control procedures and promote the development and testing of novel RDTs.
FIND partnered with the National Institute for Biological Standards and Control (NIBSC) to create the first World Health Organization (WHO) IS for P. falciparum antigens, by conducting an international collaborative study in 13 laboratories across 11 different countries. FIND provided funding for the study, contributed to the development of protocols and standard operating procedures, identified key partners, and facilitated the selection and transfer of clinical samples from the WHO specimen bank.
The IS that was validated by the study and subsequently endorsed by the WHO Expert Committee on Biological Standardization (ECBS) contains 1000 International Units of HRP2 and 1000 International Units of pLDH per ampoule.
On 19 October, the IS was officially endorsed by WHO ECBS. On the same day, WHO ECBS endorsed proposals for “the first International Standard for Plasmodium vivax antigens” and the “1st WHO Reference Reagent for Anti-Malaria (Plasmodium vivax) human serum.” FIND will collaborate with the NIBSC on the development of these standards, providing funds and raw materials for evaluation.
These standards will be used worldwide for the quality control and regulation of RDTs and similar in vitro assays. They will also be used to support the development of more sensitive RDTs and to calibrate other reference materials and controls, including panels of recombinant proteins and positive wells being developed by FIND. The calibration of recombinant panels is a key use of the IS for the new WHO decentralized RDT lot testing programme, which relies on these panels as a substitute for patient samples to lower costs and increase sustainability of malaria RDT quality control procedures.
Posted by Dr. Tim Sandle