Vitamin B12 Deficiency and Fish Tapeworms

Diphyllobothrium latum, or the fish tapeworm, is basically a Scandinavian import to the United States. As Robert Desowitz describes in his classic book "New Guinea Tapeworms and Jewish Grandmothers", many Scandinavian fishermen settled in the cool lake regions of Minnesota and Wisconsin in the nineteenth century and continued to fish for a living but with ["]