Spirometra

Spirometra is a genus of tapeworms in the family Diphyllobothriidae. Adults inhabit the small intestines of various carnivorous mammals, including dogs and cats, and produce eggs that pass in the host’s feces. The genus includes several species, notably Spirometra erinaceieuuropaei, which is the species most commonly associated with human sparganosis, though other Spirometra species can also infect humans.

The life cycle of Spirometra involves two intermediate hosts and a definitive host. Eggs hatch into free-swimming coracidia in water, which are ingested by copepods (the first intermediate hosts) and develop into procercoids. These copepods can then be eaten by second intermediate hosts such as fish, amphibians, or reptiles, where the larvae become plerocercoids (spargana). Definitive hosts, typically canids or felids, acquire the adult tapeworm by consuming the second intermediate host. Humans are accidental hosts and do not typically support the complete life cycle; sparganum larvae may migrate through tissues, causing sparganosis.

Clinical manifestations in humans depend on larval location and burden. Subcutaneous sparganosis presents as nodules; migration to the eye, central nervous system, or other tissues can occur and may cause vision problems, neurological symptoms, or inflammation.

Diagnosis relies on imaging, serology (such as ELISA), and sometimes biopsy of migratory lesions or nodules. Treatment for localized sparganosis is usually surgical removal of accessible spargana; antiparasitic drugs like praziquantel or albendazole may be variably effective and are not universally curative.

Prevention focuses on avoiding ingestion of raw or undercooked second intermediate hosts, preventing contamination of drinking water, and avoiding the use of traditional poultices made from infected animal tissue.