A Monte Carlo study on intraerythrocytic staging of malaria parasite using photoacoustics

Malaria parasite during its intraerythrocytic development digests considerable amount of hemoglobin (Hb) of the host red blood cell (RBC) and converts into a polymerized form of heme, referred to as hemozoin (Hz). The molar extinction coefficient of Hz greatly differs from that of Hb at certain optical wavelengths. Consequently, light absorption and hence, photoacoustic (PA) emission of an infected cell would vary from that of a normal cell. The PA signals were calculated from simulated blood samples with various stages of infection (normal, ring, trophozoite and schizont) employing a theoretical model. A Monte Carlo algorithm was used to simulate tissue samples in 3D. The simulation results showed that the PA amplitude monotonically decreased and increased with parasite growth, when probed with 411 and 700 nm laser beams, respectively. The PA amplitude for an ensemble of infected cells (schizont stage) was nearly 2 times lower at 411 and 79 times higher at 700 nm than that of healthy RBCs. The PA spectral power also demonstrated similar trends. For example, at 7.5 MHz spectral power nearly decreased by 6 dB and increased by 38 dB between the same stages at those optical wavelengths, respectively. It is conjectures that it may be feasible experimentally to differentiate intraerythrocytic stages of malaria parasite when illuminated by a suitable optical radiation.