SUMMARY AND EXPLANATION THE TEST
Malaria is a mosquito-borne, hemolytic, febrile illness that infects over 200 million people and kills more than 1 million people per year. It is caused by four species of Plasmodium: P. falciparum, P. vivax, P. ovale, and P. malariae. These plasmodia all infect and destroy human erythrocytes, producing chills, fever, anemia, and splenomegaly. P. falciparum causes more sever disease than the other plasmodial species and accounts for most malaria deaths, and it is one of the two most common malaria pathogens.
Traditionally, malaria is diagnosed by the demonstration of the organisms on Giemsa stained thick smears of peripheral blood, and the different species of plasmodium are distinguished by their appearance in infected erythrocytes. The technique is capable of accurate and reliable diagnosis, but only when performed by skilled microscopists using defined protocols, which presents major obstacles for the remote and poor areas of the world.
The Pf Ag Rapid Test is developed for solving these obstacles. It detects the Pf specific antigen pHRP-II in human blood specimen. It can be performed by untrained or minimally skilled personnel, without laboratory equipment.
PRINCIPLE
The Pf Ag Rapid Test is a lateral flow chromatographic immunoassay. The test strip components consist of: 1) a burgundy colored conjugate pad containing monoclonal anti- pHRP-II antibody conjugated with colloid gold (pHRP II-gold conjugates), 2) a nitrocellulose membrane strip containing a test band (Pf) and a control band (C band). The Pf band is pre-coated with polyclonal anti-pHRP-II antibodies, and the C band is pre-coated with goat anti-mouse IgG.
During the assay, an adequate volume of the blood specimen is dispensed into the sample well (S) of the test cassette, a lysis buffer is added to the buffer well (B). The buffer contains a detergent that lyses the red blood cells and releases the pHRPII antigen, which migrates by capillary action across the strip held in the cassette. pHRP-II if presents in the specimen will bind to the pHRP II-gold conjugates. The immunocomplex is then captured on the membrane by the pre-coated polyclonal antipHRP II antibodies, forming a burgundy colored Pf band, indicating a Pf positive test result.
Absence of the Pf band suggests a negative result. The test contains an internal control (C band) which should exhibit a burgundy colored band of the immunocomplex of goat anti-mouse IgG / mouse IgG (pHRP II–gold conjugates) regardless of the color development on any of the Pf band. Otherwise, the test result is invalid and the specimen must be retested with another device.
