Spirometra mansoni (Sparganosis)

Biology
The parasites use two intermediate hosts during its life cycle. The adults live in the small intestine of dogs or cats (which eat the fish, reptiles, or amphiians) and then pass on unembryonated eggs in feces into water. The eggs embryonate in water to form coracidia, which then enter into copepods (small crustaceans present in water), which are ingested by fish, reptiles, or amphibians. These are in turn ingested by dogs or cats, and the life cycle continues. Humans become infected by the procercoid larvae, either directly from water containing infected copepods or from eating an undercooked second intermediate host. Humans can also acquire it by contact, which is mainly by application of frog flesh as a poultice used as traditional medicine in several countries in Asia.

Epidemiology
In a large study from China, central nervous system involvement occurred in 18% of cases overall from 1959 to 2012, but CNS involvement increased in prevalence to representing 48% of cases after the year 2000. The increase in recent years is most likely due to the ability to easier diagnose these disorders with brain imaging. The vast majority of these involve infiltration of the brain, but rarely the spinal cord or vertebral canal can be affected.

Age range: can affect all ages, most common in those under age 50.

Risk factors

 * Using frog or snake flesh as a poultice in traditional medicine
 * Consuming undercooked meat, most commonly frogs or snakes, occasionally poultry
 * Drinking water with the presence of infected copepods
 * Using herbs as a poultice that are contaminated with infected water

Signs/symptoms
Rarely the worm can infiltrate into the spinal canal.