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trichinosis; trichinellosis

Etiology: 1) infection with Trichinella spiralis acquired by ingestion of incompletely cooked pork, pork products, or less commonly bear meat [5] that contains infective larva 2) pork may contaminate chopped or ground beef Epidemiology: - 50 cases/year in U.S. Pathology: 1) the ingested larvae mature in the small intestine, with the mature female producing new larvae for 2-3 weeks 2) larvae enter lymphatics & venules & spread through the general circulation from where they invade the skeletal muscle & undergo further development & encapsulation 3) encysted or encapsulated larvae remain viable for several years 4) eventually calcification renders the larvae inviable Clinical manifestations: 1) GI symptoms during intestinal development of larvae 2) fever, muscle pain, myocarditis, respiratory difficulties*, & periorbital edema during migratory & encapsulation phase 3) petechial hemorrhages & ecchymoses may occur 4) 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 [4] Laboratory: 1) eosinophilia during migratory & encapsulation phase 2) elevation of serum creatine kinase 3) Trichinella serology - Trichinella spiralis serology 4) skeletal muscle biopsy (gastrocnemius or deltoid) showing trichenella cysts rarely needed [4] Management: 1) current antihelmintic agents are ineffective against Trichinella larvae in muscle 2) mebendazole & thiabendazole are active against enteric stages of Trichinella 3) prednisone 1 mg/kg for 5 days for severe myositis & myocarditis

Related

Trichinella spiralis

General

helminth infection

References

  1. Clinical Diagnosis & Management by Laboratory Methods, 19th edition, J.B. Henry (ed), W.B. Saunders Co., Philadelphia, PA. 1996, pg 1296
  2. Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 1206
  3. Medical Knowledge Self Assessment Program (MKSAP) 11, 18. American College of Physicians, Philadelphia 1998, 2018
  4. Rothaus C A Tricky Diagnosis. NEJM Resident 360. Oct 3, 2018 https://resident360.nejm.org/content_items/a-tricky-diagnosis
  5. Cash-Goldwasser S, Ortbahn D, Narayan M, et al. Outbreak of Human Trichinellosis - Arizona, Minnesota, and South Dakota, 2022. MMWR Morb Mortal Wkly Rep 2024;73:456-450 PMID: 38781100 https://www.cdc.gov/mmwr/volumes/73/wr/mm7320a2.htm