Plasmodium Knowlesi - Diagnosis

Diagnosis

P. knowlesi infection is diagnosed by examining thick and thin blood films in the same way as other malarias. The appearance of P. knowlesi is similar to that of P. malariae and is unlikely to be correctly diagnosed except by using molecular detection assays in a malaria reference laboratory.

The morphology of Plasmodium knowlesi is similar to that of Plasmodium malariae. P. malariae is characterized by a compact parasite (all stages) and does not alter the host erythrocyte's shape or size or cause enlargement. Elongated trophozoites stretching across the erythrocyte, called band forms, are sometimes observed. Schizonts will typically have 8-10 merozoites that are often arranged in a rosette pattern with a clump of pigment in the center.

Rapid diagnostic tests kits may or may not recognize P. knowlesi because of their specificity.

Currently PCR assay and molecular characterization are the most reliable methods for detecting and diagnosing P. knowlesi infection. PCR identifies the parasite DNA but this technique is not rapid and cannot be used for routine identification. PCR is also expensive and requires very specialized equipment.