Figure 7.

Heat stress induced abnormal morphology in P. falciparum. Control P. falciparum morphology showed trophozoites (a) that were large, full, well-rounded with clear and concentrated haemazoin and relatively even staining; and ring-stage parasites (b) that showed lightly-stained, delicate and rounded rings with single chromatin dots. In contrast, 24 h after exposure to 41 °C for 2 h, trophozoites (c) appeared unevenly stained with jagged borders and cytoplasmic vacuoles (ci–iii), or were condensed and very darkly stained (civ). Ring-stage parasites that were exposed to the same stress (d) showed variable morphology at 24 h. Some rings appeared slightly vacuolised (di) and remained as ring-stage parasites 24 h after exposure instead of progressing to trophozoites. Some morphologically normal trophozoites were also observed (dii). Many ring-stage parasites were abnormally large with a central vacuole (diii). Chromatin-like dots without any ring structure were also observed in many cells (div)