A field mouse found on Svalbard, an island group in the Arctic Ocean north of Norway, has been found to harbor Echinococcus multilocularis, a parasitic tapeworm endemic to central Europe that can cause fatal liver cysts. Two scientists who worked in the area have tested positive for the parasite, which is usually passed to humans from dogs or foxes that acquire it by eating infected mice and then excrete the tapeworm's eggs. The incubation period is from 5 to 15 years, and the infection usually manifests as epigastric pain or chronic cholestatic jaundice. Svalbord has a small population, but about 14,000 tourists visit the island every year. Residents have been warned to wash their hands after touching dogs or foxes, and to boil water taken from streams and rivers.
Surgical excision is the only reliable means of treatment.