Globally, there are over 200 million annual cases of malaria causing an estimated 660,000 deaths. Malaria accounts for about one quarter of non-neonatal childhood mortality and is the greatest disease burden in Africa in disability adjusted life years.
Mechanism of Action:
Malaria is detected through two broad strategies: microscopy and antigen tests.
Microscopy can diagnose malaria through skilled examination of either thin or thick film samples of blood. A small sample, ~1ml, of blood is taken from the patient and examined under a microscope. This test can diagnose malaria parasites down to concentrations of 20 parts per microliter. Furthermore, the test can cost less than $0.50 in some facilities in the right conditions with high throughputs.
Rapid Diagnostic Tests (RDTs), on the other hand, are point-of-care tests. Costing $0.60-$2.50, an RDT can be used in clinics and by community health workers. RDTs react to antigens found in the blood of a person infected with malaria. A particular RDT will respond only to certain strains of malaria infection and so must be chosen for the region.
Current use in High-Resource Settings:
The standard diagnostic in high-resource settings is a microscopy based test done in a laboratory setting. RDT's are seldom used, as malaria is uncommon in these settings.
Current Use in Low-Resource Settings:
Both microscopy and RDTs are common in low income contexts. Microscopy has been the standard of care, though issues with microscope reliability, technical skill, and laboratory turnaround time are problematic in many locations.
Rapid diagnostic tests are increasingly common. The tests are inexpensive and do not require specialized training. However, the proliferation of different tests requires diligence to ensure that the selected test is appropriate, accurate, and stored in a way in which its effectiveness will be maintained. The WHO has carried out interventions using RDTs and found many of them appropriate and effective.