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NOTE: A surveillance case definition is a set of uniform criteria used to define a disease for public health surveillance. Surveillance case definitions enable public health officials to classify and count cases consistently across reporting jurisdictions. Surveillance case definitions are not intended to be used by healthcare providers for making a clinical diagnosis or determining how to meet an individual patient’s health needs.

CSTE Position Statement(s)

  • 13-ID-06

Clinical Description

A disease caused by ingestion of Trichinella larvae, usually through consumption of Trichinella-containing meat—or food contaminated with such meat—that has been inadequately cooked prior to consumption. The disease has variable clinical manifestations. Common signs and symptoms among symptomatic persons include eosinophilia, fever, myalgia, and periorbital edema.

Laboratory Criteria For Diagnosis

Human Specimens

  • Demonstration of Trichinella larvae in tissue obtained by biopsy, OR
  • Positive serologic test for Trichinella

Food Specimens

  • Demonstration of Trichinella larvae in the food item (probable)

Epidemiologic Linkage

Persons who shared the implicated meat/meal should be investigated and considered for case status as described above.

Criteria to Distinguish a New Case from an Existing Case

Serial or subsequent cases of trichinellosis experienced by one individual should only be counted if there is an additional epidemiologically compatible exposure. Because the duration of antibodies to Trichinella spp. is not known, mere presence of antibodies without a clinically-compatible illness AND an epidemiologically compatible exposure may not indicate a new infection especially among persons with frequent consumption of wild game that is known to harbor the parasite.

Case Classification


Instances where there is no clinically compatible illness should be reported as suspect if the person shared an epidemiologically implicated meal, or ate an epidemiologically implicated meat product, and has a positive serologic test for trichinellosis (and no known prior history of Trichinella infection).


A clinically compatible illness in a person who shared an epidemiologically implicated meal or ate an epidemiologically implicated meat product.


A clinically compatible illness in a person who consumed a meat product in which the parasite was demonstrated.


A clinically compatible illness that is laboratory confirmed in the patient.


Epidemiologically implicated meals or meat products are defined as a meal or meat product that was consumed by a person who subsequently developed a clinically compatible illness that was laboratory confirmed.

Negative serologic results may not accurately reflect disease status if blood was drawn less than 3-4 weeks from symptom onset (Wilson et. al, 20061).


  1. Wilson M, Schantz P, Nutman T, 2006. Molecular and immunological approaches to the diagnosis of parasitic infection. Detrick B, Hamilton RG, Folds JD, eds. Manual of Molecular and Clinical Laboratory Immunology. Washington, DC: American Society for Microbiology, 557-568.

Related Case Definition(s)