trichinosis; trichinellosis

Etiology

• infection with Trichinella spiralis acquired by ingestion of incompletely cooked pork, pork products, or less commonly bear meat that contains infective larva
• pork may contaminate chopped or ground beef

Epidemiology

• 50 cases/year in U.S.

Pathology

• the ingested larvae mature in the small intestine, with the mature female producing new larvae for 2-3 weeks
• larvae enter lymphatics & venules & spread through the general circulation from where they invade the skeletal muscle & undergo further development & encapsulation
• encysted or encapsulated larvae remain viable for several years
• eventually calcification renders the larvae inviable

Clinical manifestations

• GI symptoms during intestinal development of larvae
• fever, muscle pain, myocarditis, respiratory difficulties*, & periorbital edema during migratory & encapsulation phase
• petechial hemorrhages & ecchymoses may occur
• few if any symptoms after parasites have encysted

* trichinella does not migrate through lung tissue, but respiratory symptoms are common due to larval invasion of chest & myocardial muscle or a pulmonary reaction to larvae passing through the pulmonary circulation

Laboratory

• eosinophilia during migratory & encapsulation phase
• elevation of serum creatine kinase
• Trichinella serology
  • Trichinella spiralis serology
• skeletal muscle biopsy (gastrocnemius or deltoid) showing trichenella cysts rarely needed

Management

• current antihelmintic agents are ineffective against Trichinella larvae in muscle
• mebendazole & thiabendazole are active against enteric stages of Trichinella
• prednisone 1 mg/kg for 5 days for severe myositis & myocarditis

More general terms

• helminth infection

Additional terms

• Trichinella spiralis