Objective: To investigate growth of Echinococcus granulosus protoscoleces in BALB/c mice and gerbils and their susceptibility for secondary cystic echinococcosis.
Design of study: Prospective experimental study.
Animals: Forty two BALB/c mice, fifty four gerbils and one rabbit were used.
Material and Methods: Echinococcus granulosus protoscoleces were aspirated aseptically from fertile sheep hydatid cysts of lungs and livers. Protoscoleces were checked under light microscope for motility to ensure viability prior to passage. BALB/c mice and
gerbils were inoculated interperitoneally. Each animal received approximately 2000 protoscoleces. A single rabbit was also injected
with about 200,000 protoscoleces. Animals were euthanized and investigated for the presence of proto scoleces or developing cysts. Results: By the second week post-infection (wpi), in both mice and gerbils, some white glistening masses of 2-3 mm in diameter
were visible in the abdominal cavity. At six wpi 6-8% of protoscoleces were viable. Over the course of infection (46 weeks) 38 mice (92%) were developed hydatid cysts. For gerbils the rate of cyst development after 72 wpi was 83.3% (45/54). The infected rabbit was euthanized at 56 wpi and 15 hydatid cysts were developed. Discussion: The development of granuloma (2-3mm) around protoscoleces after 2 wpi in both gerbils and mice indicated that a host cellular response was made to the parasite. Decreasing viability of proto scoleces indicates that they may be damaged by host immune system. According to our results mice and gerbils could be infected for secondary echinococcosis. Gerbils were shown to be superior to mice in terms of the development rate of fertile
cysts. J. Fac. Vet. Med. Univ. Tehran. 58, 3: 227-230, 2003