Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 35-26: Trichinosis + Key Features Download Section PDF Listen +++ +++ Essentials of Diagnosis ++ Ingestion of inadequately cooked pork or game Transient intestinal symptoms followed by fever, myalgias, and periorbital edema Eosinophilia and elevated serum muscle enzymes +++ General Considerations ++ Caused worldwide by Trichinella spiralis and related Trichinella species Transmission occurs By ingestion of undercooked meat, most commonly pork in areas where pigs eat garbage By ingestion of game and other animals, including bear and walrus in North America and wild boar and horse in Europe When infected raw meat is ingested, Trichinella larvae are freed from cyst walls by gastric acid and pass into the small intestine Larvae then invade intestinal epithelial cells, develop into adults, and the adults release infective larvae (which may be viable for years) Parasites travel via the bloodstream to skeletal muscle where they invade muscle cells, enlarge, and form cysts +++ Demographics ++ Worldwide incidence of trichinosis has decreased, but human infections continue to occur sporadically or in outbreaks, with estimates of ~10,000 cases annually In the United States, about 20 infections are reported annually, mostly from ingesting wild game + Clinical Findings Download Section PDF Listen +++ +++ Symptoms and Signs ++ Most infections are asymptomatic In symptomatic cases, gastrointestinal symptoms (eg, diarrhea, vomiting, abdominal pain) Develop within 1 week after ingestion of contaminated meat Usually last for < 1 week but can persist for much longer During the following week, migrating larvae may produce Fever, myalgias, periorbital edema, and eosinophilia (most notably) Headache Cough Dyspnea Hoarseness, dysphagia Macular or petechial rash Subconjunctival and retinal hemorrhages Systemic symptoms Usually peak within 2–3 weeks Commonly persist for about 2 months In severe cases, generally with large parasite burdens, muscle involvement can be pronounced, with severe muscle pain, edema, and weakness, especially in the head and neck Muscle pain may persist for months Uncommon severe findings include Myocarditis Pneumonitis Meningoencephalitis, sometimes leading to death +++ Differential Diagnosis ++ Eosinophilia-myalgia syndrome Eosinophilic fasciitis Dermatomyositis Influenza Polyarteritis nodosa Viral gastroenteritis Polymyalgia rheumatica Fibromyalgia Sarcocystosis + Diagnosis Download Section PDF Listen +++ +++ Laboratory Tests ++ Elevated serum muscle enzymes (creatine kinase, lactate dehydrogenase, aspartate aminotransferase) Erythrocyte sedimentation rate usually normal A commercial ELISA is available in the United States Serologic tests become positive 2 or more weeks after infection, but cross-reactivity can be seen with other parasites Rising antibody titers are highly suggestive of the diagnosis +++ Diagnostic Procedures ++ Muscle biopsy Can usually be avoided If diagnosis is uncertain, biopsy of a tender, swollen muscle may identify Trichinella larvae For maximal yield, specimen should be examined histologically, and a portion enzymatically digested to release larvae However, larvae may not be seen in muscle until 3 weeks after infection + Treatment Download Section PDF Listen +++ +++ Medications ++ No effective specific therapy for full-blown trichinosis However, mebendazole (2.5 mg/kg orally twice daily) or albendazole (5–7.5 mg/kg orally twice daily) will kill intestinal worms and may limit progression to tissue invasion +++ Therapeutic Procedures ++ Supportive therapy for systemic disease consists of Analgesics Antipyretics Bed rest Corticosteroids for severe illness + Outcome Download Section PDF Listen +++ +++ Prevention ++ Infection is prevented by cooking to a temperature of at least 71°C for at least 1 minute Irradiation of meat is also effective in eliminating Trichinella larvae Freezing is not reliable + Reference Download Section PDF Listen +++ + +Gottstein B et al. Epidemiology, diagnosis, treatment, and control of trichinellosis. Clin Microbiol Rev. 2009 Jan;22(1):127–45. [PubMed: 19136437]