Introduction
Table of Contents
Malaria is a life-threatening disease caused by Plasmodium parasites transmitted to humans through the bites of infected Anopheles mosquitoes. It is a major public health problem, with an estimated 229 million cases and 409,000 deaths globally in 2019. Early diagnosis and treatment of malaria are essential to reduce morbidity and mortality. Rapid diagnostic tests (RDTs) for malaria have emerged as a critical tool in achieving this goal.
Description of the test
The Malaria rapid diagnostic Test (RDT) is an immunochromatographic assay that detects the presence of Plasmodium antigens in whole blood. The test is a lateral flow device that consists of a sample pad, conjugate pad, nitrocellulose membrane, and an absorbent pad. The membrane contains a control line and a test line. The test takes about 15 minutes to complete.
Indications
The Malaria RDT Test is indicated for the rapid diagnosis of malaria in patients with fever or other symptoms suggestive of malaria.
Test Principle
The Malaria RDT Test works by detecting P. falciparum histidine rich protein 2 (HRP-2) or P.vivax lactate dehydrogenase (pLDH) antigens in whole blood. The test uses a monoclonal antibody that is conjugated to colloidal gold particles to bind to the pLDH antigens. If the pLDH antigen is present in the sample, it will bind to the antibody-gold conjugate and form a complex. The complex then migrates along the nitrocellulose membrane and is captured by a second antibody that is immobilized on the test line. If the pLDH antigen is absent, no complex will be formed, and the test line will not be visible. A control line that detects the presence of the reagents and proper flow of the sample is also present. In Kenya, there are RDT kits that detect P.falciparum only (univalent) or two ( addition, to p. Vivax, Divalent Test).
Sample
The Malaria RDT Test requires a fingerstick or venous whole blood sample.
Test Preparation / Instructions
The test kit should be stored at room temperature (15-30°C) until use. Before testing, the sample should be mixed thoroughly by inverting the collection tube or gently agitating the fingerstick device. The test should be performed in a well-lit area, and the instructions provided with the kit should be followed carefully.
Test Procedure
- Clean the finger with an alcohol swab and let it dry.
- Prick the finger with a lancet and collect the blood using the provided pipette.
- Apply two drops of blood to the sample well of the test device.
- Add two drops of the buffer solution to the same well.
- Read the results after 15 minutes.
Results Interpretation
A positive result is indicated by the presence of a visible line at the test line and the control line. A negative result is indicated by the presence of a visible line at the control line only. Invalid results occur if there is no visible line at the control line. In such cases, the test should be repeated with a new test device.
Reference Range
The Malaria RDT Test gives a qualitative result. The test only indicates the presence or absence of Plasmodium antigens in the sample.
Follow-up Testing
The Malaria RDT Test is a screening test and should be followed up with confirmatory testing, such as microscopy or PCR, if the result is positive. If the result is negative but clinical suspicion remains high, a repeat test or alternative diagnostic tests should be considered.
In conclusion, rapid diagnostic testing is critical in the fight against malaria.
