Abstract:
Stabilates of Theileria parva sporozoites are mostly delivered in liquid nitrogen tanks to the East
Coast fever immunization points. Using an in vitro titration model, we assessed the loss of infectivity
of several stabilates when they are stored in ice baths for up to 24 h. Comparisons, with respect to
rates of loss of infectivity, were made between T. parva stocks (Chitongo and Katete), cryoprotectants
(sucrose and glycerol) and method of assessment (in vivo and in vitro techniques). Chitongo and
Katete stabilates showed similar loss dynamics. The losses were 1–4 % (depending on parasite
stock) and 3 % per hour of storage for glycerol and sucrose stabilates respectively, and the loss rates
were not significantly different. The results suggest that Chitongo stabilates and sucrose cryoprotected
suspensions can be delivered on ice as is done for Katete.
