Diphyllobothriasis nihonkaiense: possibly acquired in Switzerland from imported Pacific salmon.

A 5-year-old Japanese boy passed tapeworm strobila while he was living in Switzerland. During a short visit to Japan, he was successfully treated with a single dose of praziquantel. DNA sequences of ITS1, cox1 and nd3 genes from the tapeworm were compatible with those of Diphyllobothrium nihonkaiense rather than Diphyllobothrium latum, which is prevalent in Europe. The patient consumed imported salmon in Switzerland. This case highlights the globalization of D. nihonkaiense, which was once restricted to the Far East, and reflects the worldwide demand for seafood.