Merck Manual

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Chelsea Marie

, PhD, University of Virginia;

William A. Petri, Jr

, MD, PhD, University of Virginia School of Medicine

Last review/revision Dec 2021 | Modified Sep 2022
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Adult Spirometra species and Sparganum proliferum tapeworms infect dogs, cats, and other carnivores. Eggs are passed into freshwater where they are ingested by copepods (eg, Cyclops). Fish, reptiles, and amphibians (including frogs) ingest them and serve as intermediate hosts. The tapeworms that cause sparganosis are present worldwide, but most human cases occur in Southeast Asia.

Humans and other mammals become infected by

  • Accidental ingestion of copepods from water contaminated by cat or dog feces

  • Ingestion of inadequately cooked flesh from another intermediate host

  • Contact with poultices containing flesh from these sources

In humans, larvae typically migrate to subcutaneous tissue or muscle and form slowly growing masses. Other sites, including the central nervous system, may be involved but are much less common. Symptoms are caused by mass effect. Spargana masses in the central nervous system can cause weakness, headache, seizures, numbness, tingling, or abnormal skin sensations.

Diagnosis of sparganosis is typically made after surgical removal, although it may be suggested when imaging detects a mass.

Surgery is also the primary treatment and is typically done for symptomatic, space-occupying lesions. Generally, treatment with anthelmintics has not been effective.

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NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
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