Norm of Trichinosis Skin Test
Positive of Trichinosis Skin Test
Current or past infection with T. spiralis.
Description of Trichinosis Skin Test
Trichinosis is a parasitic disease caused by the larvae of Trichinella spiralis, a roundworm acquired in humans by ingestion of raw or poorly cooked pork or other animals it inhabits (cats, dogs, swine, and some wild animals such as walrus and bear). The ingested worm larvae mature and reproduce in the intestinal tract and then migrate through the lymphatic system and bloodstream to other sites in the body. Those reaching muscle tissue become encapsulated as cysts, causing inflammation and necrosis. The symptoms of trichinosis are progressive. Soon after ingestion, hyperpyrexia, gastrointestinal upset, eosinophilia, and muscle edema occur. These symptoms are followed by muscle soreness and may progress to neurotoxicity and myocarditis. This test is based on an immediate hypersensitivity reaction. The presence of T. spiralis antibodies is indicated when intradermal injection of the killed larvae of T. spiralis produces signs of an antigen-antibody reaction.
Professional Considerations of Trichinosis Skin Test
Consent form NOT required.
- Obtain an alcohol wipe, a 4-mL syringe with an intradermal needle, T. spiralis antigen, and a control.
- Assess for history of recent ingestion of raw pork or poorly cooked pork or other susceptible animals.
- Cleanse the forearm site for injection with an alcohol wipe and allow the area to dry.
- Inject T. spiralis antigen intradermally. Inject the control into the site in the opposite forearm. Record the sites of injection.
- 20 minutes later, observe the injection site for a blanched wheal with surrounding erythema, a symptom of a positive reaction.
Client and Family Teaching
- Thoroughly cook pork or meat from other susceptible animals.
- In positive tests, the wheal and redness should disappear within a few hours.
Factors That Affect Results
- Positive results may also indicate past trichinosis infection.
- Injected corticosteroids may help mediate an excessive reaction to the skin test.
- See also Trichinosis serology—Serum.