Maintenance of in vitro cultures of Babesia divergens and Babesia major at low temperatures.

Cultures of erythrocytes parasitized by Babesia divergens and Babesia major were stored in medium cooled to 4 degrees C for up to 8 weeks. There was a marked decrease in parasitaemia and an increase in the number of free extra-erythrocytic, unagglutinated merozoites, during the cooled period. Cultures stored in this way and returned to 38 degrees C resumed growth, with or without sub-culture. At the low temperature, only one sub-culture is required per week.