Light microscopical study of Blastocystis spp. in monkeys and fowls

An investigation of a Blastocystis species obtained from several species of monkeys and fowls was conducted to clarify the morphology of the organism, using light microscopical techniques including Giemsa, Heidenhain iron hematoxylin, Trichrome stains, iodine mount and phase-contrast microscopy. A comparison was made with Blastocystis hominis from humans. Blastocystis spp. were found in 15 out of 26 monkeys and in all of 12 fowls (10 chickens and 2 ostriches) examined. The behaviour of the parasites in the bowels was also examined, using paraffin-embedded sections. Microscope examination of the lumen contents at death revealed the organism in the caecum of monkeys and fowls. The organisms from faeces, cultures and the lumen contents of the caecum of humans, monkeys and fowls were similar, except for variations in the size and contents of the central vacuoles, which occupied the centre of the organisms.