Trichinosis

Cause: Intestinal roundworm Trichinella spiralis.

Illness and treatment: Ingested larvae migrate and become encapsulated in muscle. Infection ranges from asymptomatic to severe, depending on the dose. Diarrhea may occur first. There is usually sudden onset of muscle pain, swelling of the upper eyelids, and recurring fever. Death can result from damage to heart muscle. Treatment depends on the stage of illness at diagnosis.

Sources: The infection is caused by ingesting raw or insufficiently cooked meat from infected animals. Historically, undercooked pork was a risk. Wild game is now the most likely exposure in North America. There is no person-to-person spread.

Additional risks: Freezing meat will not necessarily inactivate larvae of artic strains.

Prevention: Cook or irradiate all wild game to reliably kill larvae. Regulations to prevent trichinosis require the cooking of garbage and offal fed to swine.

Recent Washington trends: In the past decade only 2 cases have been reported. Exposures were bear and cougar meat eaten raw or undercooked.

Purpose of Reporting and Surveillance

  • To identify sources of transmission (e.g., contaminated meat) and to prevent further transmission from such sources
  • To educate exposed persons about signs and symptoms of disease, thereby facilitating early diagnosis
  • To educate people about how to reduce their risk of infection.

Legal Reporting Requirements

  • Health care providers: notifiable to local health jurisdiction within 3 business days
  • Health care facilities: notifiable to local health jurisdiction within 3 business days
  • Laboratories: Trichinella species notifiable to local health jurisdiction within 2 business days. Specimen submission is on request only
  • Local health jurisdictions: notifiable to the Washington State Department of Health (DOH) Communicable Disease Epidemiology (CDE) within 7 days of case investigation completion or summary information required within 21 days.