Background: Cystic Echinococcosis (CE) is a widespread neglected zoonotic disease caused by the larval stage of the dog
tapeworm Echinococcus granulosus sensu lato (E. granulosus s. l) that occurs in most parts of the world. Egypt is considered one of the countries where CE represents a public health concern and so far, few studies were done for molecular characterization of E. granulosus. Aim of the work: The aim of the present work was to use polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) targeting mitochondrial NADH dehydrogenase subunit 1
(nad1) for genetic characterization of Egyptian isolates of E. granulosus to infer the most probable transmission patterns.
Subjects and methods: Fifty Hydatid Cyst Fluid (HCF) and/or germinal layer samples (19 human, 23 camels, and 8 pigs) were collected from hydatid cysts. DNA was extracted from protoscolices and/or germinal layers from each individual cyst and used as template to amplify nad1 gene (1071-1078 bp). The amplification products were then digested with the restriction endonuclease Haemophilus influenza (HinfI) enzyme. Results: Two RFLP patterns were obtained, pattern I in 95.2 % of samples (12 human, 21 camel and 7 pig samples) with three fragments of 115, 218, and 738 bp and pattern II in 4.8 % (2 human samples) with two fragments of 1035 and 36 bp. In total, 85.7 % of human and 100 % of camel and pig samples shared the same digestion pattern I, while pattern II appeared exclusively in two human cases out of the 14 typed (14.3 %). Conclusion: These results indicate that camels and pigs are crucial in the life cycle of E. granulosus in Egypt, although other animals may play a role.