Pediatric Trichinosis Clinical Presentation

Updated: Aug 14, 2018
  • Author: Germaine L Defendi, MD, MS, FAAP; Chief Editor: Russell W Steele, MD  more...
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Presentation

History

Most cases of trichinosis with T.spiralis are subclinical. Symptoms appear only in heavily infected individuals. Predominant symptoms (ie, GI or systemic) vary and depend on the Trichinella species ingested. The incubation period can range from a few days to 2 months. Shorter incubation periods occur when the host’s larvae load is greater.

Patients with T. nativa infection experience symptoms related only to the enteral phase; onset is delayed when compared to infection with T. spiralis, although T. nativa infections may be fatal. [13] T. nelsoni and T. britovi both have low pathogenicity in their enteral and parenteral phases.

Early (enteral/intestinal) phase for T.spiralis

Within the first week post-ingestion, gastrointestinal (GI) symptoms such as diarrhea (most common), nausea, emesis and abdominal discomfort develop. These symptoms are non-specific and mimic clinical signs of many other illnesses such as food poisoning or a viral gastroenteritis illness. These symptoms are absent in patients with mild infections, who ingest only a few viable larvae.

Acute (parenteral) phase for T. spiralis

The parenteral phase occurs when the larvae are moving their way throughout the host organism, migrating to tissues with indiscriminate invasion of different cells. This stage starts 10-14 days post-ingestion and can last about 2 months.

Hallmarks of this phase are fever (in 90% of patients), myalgias (in 90% of patients), and periorbital edema (in 80% of patients). Myalgias are common in the masseters, diaphragm, and intercostal muscles. Pain usually occurs during physical exertion. Pain at rest typically occurs in those patients with severe disease. Less common symptoms during the parenteral phase of tissue invasion include headache (in 50% of patients) and urticarial skin rash (in 20% of patients), and conjunctival and subungual hemorrhages.

Concerning symptoms will occur during this phase, as the larvae are invading the cardiac and central nervous systems. Myocarditis can occur and is typically mild and transient in nature as the larvae leave the myocardium shortly after penetrating this tissue. Involvement of the central nervous system (CNS) is more problematic as larvae migration can cause CNS granulomas and petechial hemorrhages, leading to encephalopathy. [3]

Late phase for T. spiralis

The late stage begins 5-7 weeks after the initial infection and is characterized by the disappearance of most early signs and symptoms. However, myalgias and fatigue frequently persist. In one prospective study, these symptoms persisted in 98% of patients at 2 years and in 25% of patients after 10 years. [14]

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Physical

Temperature curves illustrating a fever history exhibit variable intensity and duration; lasting for a few days in mild infection and up to 3-6 weeks in severe infections. General malaise and myalgias are also characteristic.

If periorbital or facial edema is present, it is symmetrical and produces a characteristic appearance, making patients unrecognizable. For this reason, trichinosis is often called the “disease of big heads”. Involvement of extraocular muscles can cause diplopia and blurred vision. [3]

Symptoms due to vasculitis or thromboembolic disease include subconjunctival and subungual (splinter) hemorrhages. If the cardiac, pulmonary, or nervous systems are involved, findings can indicate pericarditis, myocarditis, pneumonitis, or encephalopathy.

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Causes

Most human infections are due to T. spiralis, the Trichinella species that commonly infects pigs, wild boars and rats. [15] T. murrelli is found in black bears, raccoons, red foxes, cougars and bobcats and is the predominant species infecting wild mammals of temperate North America [7] T. britovi is found in carnivores of Europe and western Asia (eg, wild boars, horses, foxes). T. nativa infects arctic and subarctic mammals such as bears, wolves, seals and walrus; T. nelsoni is common in African predators and scavengers (eg, hyenas, lions, panthers). All of these species encyst.

T. pseudospiralis, T. papuae and T. zimbabwensis are species that do not encyst. T.pseudospiralis infects birds and marsupials. T. papuae and T. zimbabwensis infect saurians, crocodilians andnonavian archosaurs . T. papuae has been linked to consumption of raw soft-shelled turtles [16] and in trichinosis epidemics in Thailand. [17, 18]

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