infectious diseases
Echinococcosis
Key Points
Echinococcosis occurs when ingested tapeworm eggs hatch, releasing oncospheres, which migrate into the liver or lungs or, less frequently, to the brain, bone, or other organs and develop into cysts; no adult worms are present in the gastrointestinal tract of humans. The cysts ofE. granulosusdevelop slowly (usually over many years) into large (up to 1 L), fluid-filled cysts (hydatid cysts), which contain numerous infective protoscolices. Feces from infected dogs (and other canines) are the main source of human infection. Liver cysts cause pain and sometimes jaundice; lung cysts can cause pain, cough, and hemoptysis. E. multilocularisdoes not produce large cysts but invades and destroys surrounding tissue and can result in liver failure and death. Diagnose by CT, MRI, or ultrasound, analysis of cyst fluid, and serologic testing. Treatment varies depending on the infectingEchinococcusspecies, and the location, size, and imaging characteristics of the cysts, and may include surgery; or cyst aspiration, instillation of a scolicidal agent, and re-aspiration (PAIR); and prolonged treatment withalbendazole. 