CDC says incidence of tapeworm rising due to popularity of sushi

Most people know that raw salmon, eaten for sushi, should be frozen before serving.  Freezing destroys a tapeworm parasite found in some types of salmon.  Now the CDC has published a paper saying that the incidence of tapeworm is rising in urban populations, due to the growing popularity of sushi and sashimi.  Here is the article we wrote about this today in Seafood.com News.   Popularity of sushi has led to increase in tape worm infections in urban populations

SEAFOOD.COM NEWS by John Sackton - June 17, 2009 - Tapeworm parasites transmitted from eating raw salmon used to be endemic in some rural areas of Japan. However, researchers now say that the global popularity of sushi has led to an increase in tapeworm infestation in urban populations who eat more raw fish. In some species of pacific salmon, which are used by tapeworms as part of their life cycle, the eggs can be killed by freezing.  The paper, published by the CDC in the current edition of its Emerging Infectious Diseases Journal, says 'the incidence of human infection with the broad tapeworm Diphyllobothrium nihonkaiense has been increasing in urban areas of Japan and in European countries.  A recent surge of clinical cases highlights a change in the epidemiological trend of this tapeworm disease from one of rural populations to a disease of urban populations worldwide who eat seafood as part of a healthy diet. The graph shows the increasing incidence of tape worm associated with eating raw salmon that has been recorded among some populations. "Annual incidence rates of the clinical cases show an apparent surge in recent years (Figure 2). In a broad assumption that the case numbers at MZ represent all cases of this tapeworm infection in Kyoto, the average incidence in the past 20 years was 0.32 cases per 100,000 population per year, and that in 2008 was 1.0 case per 100,000 population. " "Most patients regularly ate sushi and sashimi. Approximately half could recall that they ate raw or undercooked salmon in the past 6 months. Analyses of 149 cases at MZ and BH showed that the disease occurred during all seasons but that prevalence peaked in early summer (Figure 3). Every age group was affected, from 3 to 77 years. Most patients were 20Ð59 years of age, which probably reflects more frequent consumption of sushi and sashimi by persons in this age group than in other age groups. Twice as many men than women were affected."