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. P. falciparum and P. vivax are the most common pathogens, however, there is considerable geographic variation in species distribution.
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 erythrocytes1. The technique is capable of accurate and reliable diagnosis, but only when performed by skilled microscopists using defined protocols2, which presents major obstacles for the remote and poor areas of the world.
The Malaria Pf / Pan Antigen Rapid Test Kit is developed for solving these obstacles. The test utilizes a pair of monoclonal and polyclonal antibodies to P. falciparum specific protein, Histidine Repeat Protein II (pHRP-II), and a pair of monoclonal antibodies to plasmodium Lactate Dehydrogenase (pLDH), a protein produced by the four species of the plasmodium, thus enables simultaneous detection and differentiation of the infection with P. falciparum and or any of the other three plasmodia. It can be performed by untrained or minimally skilled personnel, without laboratory equipment.
PRINCIPLE
The Pf/ Pan Malaria Rapid Test kit is a lateral flow chromatographic immunoassay. The test strip components consist of: 1) a burgundy colored conjugate pad containing mouse anti- pHRP-II antibody conjugated with colloid gold (pHRP II-gold conjugates) and mouse anti-pLDH antibody conjugated with colloid gold (pLDH-gold conjugates),
2) a nitrocellulose membrane strip containing two test bands (Pan and Pv bands) and a control band (C band). Pan band is pre-coated with monoclonal anti-pLDH antibody by which the infection with any of the four species of plasmodia can be detected, the Pf band is pre-coated with polyclonal anti-pHRP-II antibodies for the detection of Pf infection, and the C band is 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 various plasmodium antigens, which migrate 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 anti-pHRPII antibodies, forming a burgundy colored Pf band, indicating a Pf positive test result. pLDH if presents in the specimen will bind to the pLDH gold conjugates. The immunocomplex is then captured on the membrane by the pre-coated anti pLDH antibody, forming a burgundy colored Pan band, indicating a plasmodium positive test result. In the absence of Pan band, a positive test result for any of the other three plasmodia can be recommended.
Absence of any test bands (Pan and Pf) 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 and pLDH-gold conjugates) regardless of the color development on any of the test bands. Otherwise, the test result is invalid and the specimen must be retested with another device.
