not be cold enough to kill parasites. Traditionally, fish that live all or part of their lives in fresh water were considered unsuitable for sashimi due to the possibility of parasites (see Sashimi article). Parasitic infections from freshwater fish are a serious problem in some parts of the world, particularly Southeast Asia. Fish that spend part of their life cycle in brackish or fresh water, like salmon (which really are anadromous coastal trout), are a particular problem. A study in Seattle, Washington showed that 100% of wild salmon had roundworm larvae capable of infecting people. In the same study farm-raised salmon did not have any roundworm larvae. Parasite infection by raw fish is rare in the developed world (fewer than 40 cases per year in the United States), and involves mainly three kinds of parasites: Clonorchis sinensis (a trematode/fluke), Anisakis (a nematode/roundworm) and Diphyllobothrium (a cestode/tapeworm). Infection risk of Anisakis is particularly higher in fishes which may have lived in a river or estuary, such as salmon (sa ke in Japanese cuisine) or mackerel (sa ba in Japanese cuisine). Such parasite infections can generally be avoided by boiling, grilling, preserving in salt or vinegar, or deep-freezing. In Japan, it is common to eat raw salmon and ikura (roe), but these foods are frozen overnight prior to eating to prevent infections from parasites, particularly Anisakis. Pescetarianism The neologism "pescetarian" covers those who eat fish and other seafood, but not mammals and birds. A 1999 metastudy combined data from five studies from western countries. The metastudy reported mortality ratios, where lower numbers indicated fewer deaths, for pescetarians to be 0.82, vegetarians to be 0.84, and occasional meat eaters to be 0.84. Regular meat eaters and vegans shared the highest mortality ratio of 1.00. However, the "lower mortality was due largely to the relatively low prevalence of smoking in these [vegetarian] cohorts". Since fish is animal flesh, the Vegetarian Society has stated that vegetarian diets cannot contain fish. In religion Religious rites and rituals regarding food also tend to classify the birds of the air and the fish of the sea separately from land-bound mammals. Sea-bound mammals are often treated as fish under religious laws – as in Jewish dietary law, which forbids the eating of cetacean meat, such as whale, dolphin or porpoise, because they are not "fish with fins and scales"; nor, as mammals, do they chew their cud and have