Further Studies on the Cultivation of the Avian Malaria Parasites

Abstract

Summary Experiments involving the cultivation of three species of avian plasmodia, Plasmodium cathemerium, P. hexamerium and P. relictum, on the Harvard medium show the medium to be best adapted to the requirements of P. hexamerium. Although the Growth Index (defined as the ratio of parasites per unit number of red cells at the end of a given period of cultivation to that at the start) was numerically not as high as that obtained with some other species of avian plasmodia, it represents a relatively better result because this species has a much slower rate of natural increase. Viability tests and staining reactions of cultured parasites confirm this conclusion. Relatively good results were also obtained in subculture. Nevertheless even this species does not show a rate of multiplication in culture approaching that observed in vivo. Of the other two species, P. relictum (as previously reported) does moderately well in primary cultures, but little more than survival occurs in subcultures. P. cathemerium shows even less multiplication in primary cultures, and virtually none in subculture.