Hydatidosis: The Time Required for Protoscolices Implantation in the Peritoneal Cavity of Rats

Background: Hydatid disease is a parasitic infection caused by the larval stage of E. granulosus whose life cycle involves livestock and dogs as intermediate and definitive hosts, respectively. Surgery is a common treatment for hydatid cysts but rupture of cyst and spillage of the contents may cause secondary implantation of cysts. The objective of this study was to determine the time required for protoscolices implantation in different organs. Materials and Methods: Thirty-six rats were divided into six groups of 6 animals each. The rats in five groups were injected intraperitoneally with 2 milliliters of hydatid fluid containing 100 protoscolices but the rats in sixth group (as control group) were injected with 2 milliliters of normal saline. The rats in groups I, II, III, IV and V were sacrificed and opened after 1, 24, 48 , 72 and 168 hours, respectively. All internal organs were evaluated carefully and 3 samples from liver, omentum and intestine were prepared for light microscopy. Results: There was no implantation of protoscolices in the tissues of first, second and third groups of rats. But protoscolices were implanted in tissue samples of fourth and fifth group that were sacrificed 72 and 168 hours after injection. Conclusion: The protoscolices of hydatid cyst need at least 72 hours for implantation after intraperitoneal spillage.