Update on Malaria Diagnostics and Test Utilization

Abstract

Malaria is a potentially life-threatening disease requiring rapid diagnosis and treatment. Although microscopic examination of thick and thin blood films remains the gold standard for laboratory diagnosis, rapid antigen tests and nucleic acid amplification methods may also play a useful role in detection of acute infection. This review discusses the advantages and disadvantages of the commonly used diagnostic methods and provides important practice points for optimal malaria test utilization.

Keywords: diagnostics; malaria; utilization.

FIG 1

Malaria laboratory testing algorithm. ¹Algorithm includes only commonly used/available laboratory methods. Serology should not be used for detection of acute malaria. ²Malaria can be a rapidly fatal disease, particularly when due to P. falciparum, and less commonly P. vivax and P. knowlesi, and testing must be performed on a STAT basis. If testing is not available at the local laboratory, then arrangements must be made with another nearby laboratory that can provide immediate testing. A single negative test does not rule out malaria. Perform testing every 6 to 8 h for up to 3 days if clinically indicated. Other laboratory tests (e.g., complete blood count with differential, electrolyte panel, blood glucose, bilirubin, urinalysis, blood cultures) may be indicated to assess the severity of malaria and evaluate other potential causes of the patient's illness. ³Rapid screening tests such as lateral flow immunochromatographic assays generally provide sensitive detection of high levels of P. falciparum and P. vivax infection (i.e., 2,000 parasites/μl) but lack sufficient sensitivity for detecting low levels of parasitemia (i.e., ≤200 parasites/μl) and other Plasmodium species. ⁴Confirmatory testing may be performed by microscopic examination of blood films or NAAT. ⁵Examination of both thick and thin blood films is the gold standard for malaria diagnosis. ⁶If necessary, refer for confirmation of species identification by blood film microscopy or NAAT at a reference laboratory. ⁷Percent parasitemia is calculated using microscopic examination of thick or thin blood films. (Used with permission of Mayo Foundation for Medical Education and Research. All rights reserved.)