OPD (Online Plasmodium Diagnosis): An ALA-PpIX based functional assay to predict active malaria.

Abstract Background Malaria kills one child every 30 seconds reaching up to 3000 children a day. The mosquito borne malarial parasite invades the blood stream and hijacks red blood cells (RBCs). One of the medical successes of the 20th century was development of malaria diagnostic tests. However, poor specificity and sensitivity along with the inability of these assays to distinguish active malarial infections has put the management scheme in jeopardy. Aim To develop an in-vitro functional assay to predict active malarial infections. Methods Plasmodium falciparum (3D7) parasites were incubated with delta-aminolevulinic acid (ALA) for 7 h and imaged using a confocal microscope for protoporphyrin IX (PpIX) fluorescence. Similarly, PpIX was extracted, and fluorescence was estimated by fluorimetry. Results Imaging showed that the falciparum-infected RBCs fluoresced while the non-infected cells did not. Moreover, fluorimetry showed fluorescent peaks only in actively infected RBCs. Conclusions ALA was only taken up by infected RBCs. When the parasites were loaded with ALA, they fluoresced. These proof-of-concept results demonstrate the first functional assay to detect/diagnose active malaria.