A rare infestation that is caused by the larval stage of the small tapeworm (see tapeworm infestation). Larvae mostly settle in the liver, lungs, or muscle, causing the development of cysts. In rare cases, the brain is affected. The infestation is generally confined to dogs and sheep, but may be passed on to humans through accidental ingestion of worm eggs from materials contaminated with dog faeces. The cysts grow slowly, and symptoms may not appear for some years. In many cases, there are no symptoms. Cysts in the liver may cause a tender lump or lead to bile duct obstruction and jaundice. Cysts in the lungs may press on an airway and cause inflammation; rupture of a lung cyst may cause chest pain, the coughing up of blood, and wheezing. Cysts in the brain may cause seizures. Ruptured cysts may rarely cause anaphylactic shock, which can be fatal. Diagnosis of hydatid disease is by CT scanning or MRI. The cysts are usually drained or removed surgically.
Hydatid disease |
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