Comparison of manual and homogenizer methods for preparation of tick-derived stabilates of Theileria parva: equivalence testing using an in vitro titration model

Abstract

Theileria parva sporozoite stabilates are used in the infection and treatment method of immunization, a widely accepted control option for East Coast fever in cattle. T. parva sporozoites are extracted from infected adult Rhipicephalus appendiculatus ticks either manually, using a pestle and a mortar, or by use of an electric homogenizer. A comparison of the two methods as a function of stabilate infectivity has never been documented. This study was designed to provide a quantitative comparison of stabilates produced by the two methods. The approach was to prepare batches of stabilate by both methods and then subject them to in vitro titration. Equivalence testing was then performed on the average effective doses (ED). The ratio of infective sporozoites yielded by the two methods was found to be 1·14 in favour of the manually ground stabilate with an upper limit of the 95% confidence interval equal to 1·3. We conclude that the choice of method rests more on costs, available infrastructure and standardization than on which method produces a richer sporozoite stabilate.