Trichinosis (trichinellosis) is a foodborne parasitic infection caused by nematodes of the Trichinella genus, most commonly Trichinella spiralis. Humans contract this disease exclusively through consuming raw or undercooked meat containing encysted larvae. While domestic pork was historically the primary source, modern agricultural practices have reduced this risk in commercial pork. Today, most U.S. cases stem from wild game like bear, walrus, wild boar, and cougar. Globally, trichinosis affects approximately 10,000 people annually, though U.S. incidence has plummeted from 400 cases per year in the 1940s to just 16 annually by 2015.
The Parasite’s Journey
Infection begins when digestive enzymes release larvae from cysts in ingested meat. Within 1–2 days, these larvae invade the small intestine’s lining, maturing into adults that mate and produce new larvae. Early symptoms mimic food poisoning: diarrhea, abdominal cramps, nausea, and vomiting. Approximately 1–2 weeks later, the second phase erupts as newborn larvae migrate through blood vessels into muscle tissue. This triggers systemic inflammation, causing fever, periorbital swelling, muscle pain, weakness, and sensitivity to light. Severe cases may involve heart inflammation (myocarditis), breathing difficulties, or neurological complications like encephalitis. Symptoms can persist for months, with fatigue and muscle pain occasionally lingering for years.
Diagnosis and Medical Response
Diagnosis relies on a combination of dietary history (e.g., recent consumption of wild game), clinical symptoms, and blood tests showing elevated eosinophils (a type of white blood cell). Antibody tests (ELISA or Western blot) confirm infection but may return false negatives early in the disease. In ambiguous cases, a muscle biopsy can reveal coiled larvae. Treatment includes antiparasitic drugs albendazole or mebendazole, which are most effective if administered within three days of exposure, before larvae embed in muscles. For severe inflammation, corticosteroids like prednisone may be added.
Prevention: Knowledge is Key
Prevention hinges on proper meat handling:
- Cooking temperatures: Use a meat thermometer to ensure pork/wild game reaches 145–160°F (63–71°C) and rests for three minutes. Game birds require 165–180°F (74–82°C).
- Freezing: Home freezers may kill T. spiralis in pork (−15°F/−26°C for three weeks) but are ineffective against freeze-resistant species in wild game.
- Avoid risky practices: Smoking, curing, or microwaving meat does not reliably kill larvae. Contamination can also occur via shared grinders or utensils.
While rare in developed nations, trichinosis remains a global concern. Awareness in food preparation and prompt medical attention for post-exposure symptoms are critical defenses against this stealthy parasite.
