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Trichinosis - Diagnosis
Last reviewed: 03.07.2025
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During outbreaks and group diseases, in the presence of typical symptoms in patients, the diagnosis of trichinellosis does not cause difficulties.
It is necessary to establish a common source of infection and, if possible, to examine food remains (meat or meat products) for the presence of trichinella larvae. Difficulties arise in diagnosing sporadic cases of trichinellosis. In such situations, the epidemiological anamnesis is of great importance.
In the absence of data on the source of infection, a muscle biopsy is sometimes used (deltoid or gastrocnemius in bedridden patients or long back muscle in ambulatory patients): a piece of muscle tissue weighing 1 g is examined under a microscope at low magnification for the presence of Trichinella larvae.
Serological diagnostics of trichinellosis is used only in the 3rd week of the disease, since in the first 2 weeks local immune reactions prevail (intestinal phase of invasion), and the concentration of specific antibodies in the blood is low. ELISA with T. spiralis antigen and RNGA are used. The time of appearance of diagnostic antibody titers depends on the intensity of invasion and the type of pathogen: in patients with trichinellosis who became infected by eating pork heavily infested with trichinella, antibodies are detected on the 15-20th day after infection; if the intensity of invasion is less, the time of antibody detection is extended. When infected with meat of wild animals (T. s. nativa), the initial time of antibody detection can be up to 1.5 months. Specific antibody titers may increase within 2-4 months after infection, significantly decreasing after 4-5 months, but may remain at the diagnostic level for up to 1.5 years, and in case of intensive infection - up to 2-5 years. Early serological diagnostics of trichinellosis requires simultaneous implementation of two serological reactions: ELISA and RNGA. Sensitivity in these cases reaches 90-100% and specificity - 70-80%. Persons who consumed meat contaminated with trichinella undergo serological examination 2-3 weeks after preventive treatment. Diagnostic indicators of serological reactions confirm that these persons have had trichinellosis.
In all patients with trichinellosis, along with clinical blood and urine tests, a biochemical blood test, ECG, X-ray examination of the lungs are performed, and the level of electrolytes in the blood plasma is determined.
Differential diagnosis of trichinellosis
Differential diagnostics of trichinellosis is carried out with acute intestinal infections, typhoid fever and paratyphoid fever, acute respiratory infections, typhus, measles, leptospirosis, yersiniosis, Quincke's edema. With an increase in eosinophilia in the blood, trichinellosis is differentiated from the acute phase of other helminthiases (opisthorchiasis, fascioliasis, strongyloidiasis, toxocariasis), eosinophilic leukemia, nodular periarteritis, dermatomyositis.
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