Abstract
This study was designed to evaluate and compare the infection rate and cyst formation in male Balb/c mice following intraperitoneal injection of protoscoleces and activated oncospheres. Protoscoleces were collected aseptically from the liver of naturally infected sheep. The eggs were obtained from three experimentally infected dogs and activated oncospheres were prepared as described by Heath and Smyth (1970) and Kyngdon et al. (2006). A total of 20 Balb/c mice were divided into two groups of ten animals each. The mice of first and second groups were intraperitoneally infected with 1,500 protoescoleces and 1,500 activated oncosphere respectively. After 8 months of infection, all mice were euthanized, necropsied and the hydatid cysts were removed, counted, measured and weighed. The results showed that nine of ten mice of first group were infected. The maximum number of cysts was 551 in one mouse with mean size of 3.78 ± 2.21 mm and total weight of 25.48 g. The minimum number of cysts was 13 in one mouse with mean size of 3.93 ± 2.18 mm and total weight of 0.564 g. In the second group, only one mouse was infected with two cyst with mean size of 11.15 ± 1.94 mm and total weight of 1.193 g. This study showed that the male Balb/c inbred mouse is more permissive to infection with intraperitoneal injection of protoscoleces than activated oncospheres.