US salmon may carry Japanese tapeworm, scientists say

Story highlights

  • Japanese tapeworm larvae were found in wild Alaskan salmon
  • Illness and symptoms are probably the same as other tapeworms, experts say

(CNN)If you eat raw or undercooked fish, you risk developing an infection from parasites.

One of the most gruesome is tapeworm, a species of digestive tract-invading parasites that includes Diphyllobothrium nihonkaiense, or the Japanese broad tapeworm.
Though this worm was commonly believed to infect only fish in Asia, a study published Wednesday in the Centers for Disease Control and Prevention's monthly journal Emerging Infectious Diseases says wild salmon caught in Alaska had also been infected by this parasite.
    Based on those results, researchers warn that salmon caught anywhere along the Pacific coast of North America may be infected.

    Meet the tapeworm

    The most common fish tapeworm is Diphyllobothrium latum. In 1986, scientists identified another member of this family, the Japanese broad tapeworm, and believed it had been responsible for about 2,000 infections reported to that point, making it the second most common cause of tapeworm infection.
    However, continuing to study the tapeworms using new molecular methods, researchers funded by the Czech Science Foundation discovered they'd been wrong.
    Almost all of the previous cases of tapeworm infections occurring in Japan, South Korea and the Pacific coast of Russia had actually been caused by Japanese tapeworms rather than D. latum. In fact, Japanese tapeworm larvae, known as plerocercoids, could be found in salmon caught off the coasts of eastern Russia and Japan.