Trichinellosis/Trichinosis Clinical Presentation

Updated: Oct 24, 2023
  • Author: L Kristian Arnold, MD, MPH; Chief Editor: Jeter (Jay) Pritchard Taylor, III, MD  more...
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The usual incubation period of trichinellosis is 8-15 days following ingestion. As the newly released juvenile larvae invade the intestinal wall, almost all persons experience some degree of gastroenteritis. [57] Host gastroenteritis may persist for up to a couple weeks until all ingested larvae have either been expelled or died and the intestinal mucosa has recovered.

As the newborn larvae begin to enter the circulation and pass through various tissue, symptoms can be quite variable from syndromes seeming like an allergic reaction to a variety of neurologic or cardiac symptoms. Much of the cardiac and neurologic pathophysiology is based on phenomena that happen from larvae passing through individual capillaries, thus leading to symptoms either of very focal dysfunction without apparent vascular geographic logic or of diffuse processes such as encephalopathy.

Once the muscle phase starts patients may complain of muscle pains and weakness. 

Throughout the stages patients may have varying degrees of fever and rashes, currently attributed to eosinophilia and generalized activation of inflammatory biochemical pathways.

Diagnosis depends heavily upon symptoms of the disease and obtaining a thorough history to reveal any risks of the patient having ingested potentially infected meat that was not cooked enough to kill the larvae. Reports of gastroenteritis associated with fever and facial swelling and/or muscle pains in a group of persons is highly suggestive of trichinellosis.

With increasing global migration, global exotic food transport, and exotic tourism, healthcare providers in all countries should be aware of this disease and include appropriate travel and dietary questions in the history of patients with gastroenteritis, facial edema (classically palpebral), or unexplained diffuse myalgias, particularly if accompanied by eosinophilia. Unexplained or unusually high levels of eosinophilia (14-35%) in patients with vague symptoms should suggest inclusion of trichinellosis in the differential diagnostic list.

Consider the following:

  • Myalgia (75%) - Classically reported as most common in masseter, diaphragm, and intercostal muscles, though high percent reported in extremities and neck/shoulder girdle in one cohort from a large outbreak in Turkey [58] ; may be severe to point of inability to ambulate or perform simple upper extremity or truncal tasks like feeding or sitting upright

  • Fever (60-75%) - 38.5-40.5°C

  • Weakness (75%)

  • Diarrhea (40-60%) - Usually only in the acute intestinal proliferative and penetration phases of nematode infestation, though it may last for several weeks, depending on the persistence of adult worms in the intestinal wall.

  • Facial edema (40-64%) - Usually considered one of the hallmark features, particularly when localized to the eyelids (palpebral edema)

  • Headache (50-60%)

  • Fatigue/malaise (up to 95%)

  • Arthralgia

  • Cardioneurologic syndrome - Onset of these symptoms has usually been reported to occur within days following onset of general symptoms and prior to muscle invasion. [12, 59] The syndrome includes varying combinations of the following:

    • Encephalopathy

    • Focal neurologic deficits

    • Acute myocardial injury (eg, myocarditis, sinus and atrial nodal dysfunction, congestive heart failure, infarction)

    • Hypereosinophilia (≥4000 granulocytes/mm3)

  • Rash - This may occur in several forms, as follows:

    • Urticaria (most common)

    • Petechiae

    • Splinter hemorrhages

    • Palmar rash - Peripheral palmar and volar digital edema and erythema; desquamation occurs (10% in one study [60] )


Physical Examination

There are no specific physical examination actions to take other than to be diligent about a complete, detailed examination of skin for signs of a rash and attention to either palpebral edema or recent-onset edema in other body areas. 

Physical examination findings may include the following:

  • Fever (71%)

  • Palpebral edema (50-60%) - Usually considered one of the hallmark findings; may be associated with chemosis and proptosis. [61]

  • Generalized edema

  • Muscle weakness and tenderness - Usually not true neurologic weakness but pain related, although with neurologic involvement, there also may be muscle weakness

    • Respiratory difficulty may be present in persons with significant infestation of the diaphragm

  • Neurologic findings consistent with encephalopathy or focal deficits

  • Cardiac findings typical of myocarditis, pericarditis, or ischemia

  • Splinter hemorrhages have also been reported. [65]





The most serious complications are cardiac, with myocarditis leading to dysrhythmias and cardiac pump failure and neurological parenchymal involvement with, at its worst, encephalitis. Both cardiac and neurologic involvement may lead to death