Which parasite forms hydatid cysts in tissues and rupture can cause anaphylaxis?

• A. Taenia solium
• B. Echinococcus granulosus
• C. Giardia lamblia
• D. Entamoeba histolytica

Answer: (B)

Hydatid disease is caused by Echinococcus granulosus. In humans, it forms fluid-filled cysts in tissues—most commonly in the liver and lungs. A defining and dangerous feature is that rupture of these hydatid cysts can release antigen-rich fluid and protoscolices into the circulation, potentially triggering anaphylaxis. This rupture–anaphylaxis link is characteristic of Echinococcus granulosus infections.

Other parasites listed do not form hydatid cysts. Taenia solium produces cysticerci mainly in brain or muscle and does not typically cause anaphylaxis from cyst rupture. Giardia lamblia causes giardiasis with intestinal symptoms rather than tissue cysts. Entamoeba histolytica causes dysentery and liver abscesses through tissue invasion, but its cysts are not hydatid cysts, and rupture does not classically lead to anaphylaxis.