Trichinella species

Trevor A. Crowell, M.D.
Trichinella species is a topic covered in the Johns Hopkins ABX Guide.

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MICROBIOLOGY

  • Trichinosis occurs with the ingestion of undercooked meat contaminated with infective larvae of Trichinella spp.
    • 7 species of roundworms from the genus Trichinella cause human disease: T. spiralis (most common), T. nativa, T. nelsoni, T. britovi, T. pseudospiralis, T. murelli, T. papuae.
    • Species differ in infectivity for humans, host reservoirs, pathogenicity and resistance to freezing.
  • Epidemiology: worldwide.
    • From 1986-2009, there were 65,818 reported cases across 41 countries.
  • Life cycle:
    • Undercooked meat containing encysted larvae is eaten.
    • Larvae are released from the cysts with exposure to gastric acid and pepsin.
    • Larvae invade the small bowel mucosa, where they mature into adults.
    • Adult females release larvae that migrate to striated muscle where they encyst and may remain infective for years.
  • Adult worms are 1.5 x 0.05mm (male) and 3.5 x 0.06mm (females).
  • Carnivorous animals keep the life cycle going by feeding on infected rodents or meat from other animals.
  • Common hosts: pigs (most common source for human infection worldwide, but most U.S. swine fed grains and therefore uninfected), bears (most common source in the U.S.), walrus, foxes, birds, horses, hyenas, lions, and panthers.

-- To view the remaining sections of this topic, please or --

MICROBIOLOGY

  • Trichinosis occurs with the ingestion of undercooked meat contaminated with infective larvae of Trichinella spp.
    • 7 species of roundworms from the genus Trichinella cause human disease: T. spiralis (most common), T. nativa, T. nelsoni, T. britovi, T. pseudospiralis, T. murelli, T. papuae.
    • Species differ in infectivity for humans, host reservoirs, pathogenicity and resistance to freezing.
  • Epidemiology: worldwide.
    • From 1986-2009, there were 65,818 reported cases across 41 countries.
  • Life cycle:
    • Undercooked meat containing encysted larvae is eaten.
    • Larvae are released from the cysts with exposure to gastric acid and pepsin.
    • Larvae invade the small bowel mucosa, where they mature into adults.
    • Adult females release larvae that migrate to striated muscle where they encyst and may remain infective for years.
  • Adult worms are 1.5 x 0.05mm (male) and 3.5 x 0.06mm (females).
  • Carnivorous animals keep the life cycle going by feeding on infected rodents or meat from other animals.
  • Common hosts: pigs (most common source for human infection worldwide, but most U.S. swine fed grains and therefore uninfected), bears (most common source in the U.S.), walrus, foxes, birds, horses, hyenas, lions, and panthers.

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Last updated: December 5, 2019