Experimental infection of Aotus monkeys with Plasmodium falciparum Light and electron microscopic changes

Six splenectomized Aotus owl monkeys were infected with P. falciparum. The animals were sacrificed when they became moribund and tissues were faken for light and electron microscopic studies. Electron microscopy revealed marked structural changes in both the liver and the heart. In the liver there was glycogen depletion, lipid droplet infiltration mitochondrial disorganization with reduction in numbers and alterations of the microvilli in the sinusoidal pole and the bile canaliculi. In the heart, there was lipid droplet infiltration and focal disorganization of the myofibrils around the intercalated disc. There was focal mitochondrial disorganization and mitochondrial concentration around the muscle lesion. The ultrastructural changes in liver and heart were similar to those described in animals dying of shock, of at least two hours duration, in different experimental models. Ultrastructural lesions found in other organs were less marked. In the kidneys there was mainly a moderate lipid infiltration of the tubular epithelium. This change is probably the early precursor of that seen at four hours in animals dying in experimental shock. The above changes are discussed in light of the known pathophysiology of both experimental infections in animals and natural human malarial infections.