Microscopic examination of blood

The mainstay of malaria diagnosis is the microscopic examination of blood, but doctors can opt for a less invasive specimens, such saliva or urine as an alternative.

Symptomatic diagnosis

In endemic areas in the absence of microscopy, malaria is diagnosed based on clinical signs and symptoms. Yet there is little empirical evidence on the accuracy, predictability and reliability of this diagnosis within different endemic settings. Sudies carried out by the World Health Organization on patients in endemic communities in the Philippines have shown that fever alone does not discriminate well for malaria. In contrast, a sequential occurrence of fever, chills and/or sweating, or a combination of all three symptoms is a good general predictor of the disease. However, the place of diagnosis and observation (home or clinic), age, and season may affect the positive predictive values.

Field tests

In areas where microscopy is not available, or where laboratory staff are not experienced at malaria diagnosis, there are antigen detection tests that require only a drop of blood. Immunochromatographic tests (Malaria Rapid Diagnostic Tests, Antigen-Capture Assay) have been developed, distributed and fieldtested. These tests use finger-stick or venous blood, the completed test takes a total of 15–20 minutes, and a laboratory is not needed. The threshold of detection by these rapid diagnostic tests is in the range of 100 parasites/µl of blood compared to 5 by thick film microscopy.