Helminth

Trichinosis

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Trichinosis, Trichinellosis, Trichinella spiralis

  • See Also
  1. Infectious Diarrhea
  2. Parasitic Infection
  3. Helminth
  • Epidemiology
  1. U.S. infections are now rare
  • Pathophysiology
  1. Trichinella spiralis is a parasitic Roundworm found in carnivorous mammals (esp. swine and rats fed raw garbage)
  2. Humans are infected by consuming undercooked pork infected with Trichinella encysted larvae
    1. In addition to pork, other ingested meat sources include wild boar, bear, deer or ground beef
  3. After ingestion, larvae emerge from their cysts within the host's Small Intestine
    1. Cysts mature into adult worms, male and female, who then mate
    2. After mating, adult worms are passed in the host's stool
    3. Female adult worms penetrate the intestinal mucosa where they produce thousands of larvae
  4. Larvae invade the host's bloodstream and infect skeletal Muscle and various other organs
    1. Larvae encyst within skeletal Muscles where they may remain dormant for years to decades
    2. Larvae may also infect cardiac Muscle or Central Nervous System (may be fatal)
  • Symptoms
  1. Often asymptomatic with initial infection
  2. Gastrointestinal symptoms (most common, occurs with adult worm penetration of intestinal mucosa)
    1. Diarrhea
    2. Abdominal Pain or cramping
    3. Nausea or Vomiting
    4. Fever
  3. Systemic Symptoms (uncommon, occurs with larvae systemic spread to Muscle)
    1. Fever
    2. Myalgias and Myositis
    3. Eosinophilia
    4. Circumorbital edema
  • Labs
  1. Trichinella spiralis Antibody Testing
    1. Unreliable in first 3 weeks of infection
    2. Obtain 2 specimens, 2 to 3 weeks apart (consult CDC resource below)
  2. Other variable findings with Muscle invasion
    1. Complete Blood Count with Eosinophilia
    2. Lactate Dehydrogenase increased
    3. Hypergammaglobulinemia
  • Diagnostics
  1. Myositis
    1. Serum Creatine Kinase increased
    2. Muscle biopsy of Myositis location may demonstrate larvae
  2. Suspected CNS involvement
    1. Brain imaging (e.g. MRI Brain)
  • Management
  1. Albendazole
    1. Adult (and age >6 years): 400 mg orally twice daily for 8 to 14 days
    2. Child age 1 to 6 years: 5 to 10 mg/kg divided twice daily orally for 10 to 15 days
    3. Asymptomatic or mild symptoms may not require treatment
    4. Effective for enteric stages of infection (but does not affect Muscle larvae)
    5. Mebendazole or the less tolerated Thiabendazole may be used as an alternative
  2. Prednisone
    1. Consider with Albendazole in patients with severe systemic symptoms
    2. Prednisone (adult dose) 30 to 60 mg orally daily for 10 to 15 days or until symptoms improve
  • Prevention
  1. See Prevention of Foodborne Illness
  2. Full cook or freeze pork prior to ingestion
  • Complications
  1. CNS or cardiac Muscle infection
    1. Risk of fatal disease
  • Resources
  1. CDC Parasite Hotline
    1. https://www.cdc.gov/parasites/health_professionals.html
  2. Rawla (2023) Trichinella spiralis Infection, StatPearls, Treasure Island, FL
    1. https://www.ncbi.nlm.nih.gov/books/NBK538511/
  • References
  1. Gladwin, Trattler and Mahan (2014) Clinical Microbiology, Medmaster, Fl, p. 362-81
  2. Pyzocha (2023) Am Fam Physician 108(5): 487-93 [PubMed]