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Trichinosis test: antibodies to Trichinella spiralis in the blood
Last reviewed: 22.11.2021
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Antibodies to Trichinella spiralis in serum are normal.
The causative agent of trichinosis is the nematode Trichinella spiralis. The disease is accompanied by fever, development of edema, myalgia and eosinophilia in the blood. In severe course, possible damage to the myocardium and the central nervous system.
For early serological diagnosis of trichinosis, the definition of IgG antibodies using the ELISA method is used. The sensitivity of the ELISA is 90-100%, the specificity is 70-80%. Specific antibodies appear in the blood of infected Trichinella larvae and their concentration in muscles during the migration period. Their detection in serological reactions in individuals infected with eating meat of domestic animals (pigs) with high or medium intensity of trichinella infestation (200-500 larvae per 1 g of meat) occurs on the 15-20th day after infection. At a lower invasion rate, the detection of antibodies is prolonged. When people are infected from wild animals (eg, bear, wild boar, badger, nutria), antibodies are detected after 4-6 weeks. Within 2-4 months, the antibody titer may increase, and after 4-5 months after infection it begins to decrease, but remains at the diagnostic level for at least 1.5 years, and with intensive infestation - up to 2-2.5 years or more. In patients with suspected trichinosis, when a negative or questionable result of the reaction is first received, the blood test should be repeated after 10-14 days, the increase in titers confirms trichinella invasion. Serological diagnosis of trichinosis is based on a 4-fold increase in antibody titer. If it is impossible to study the serum at the beginning of the disease, examine the serum obtained during the reconvalescence period.
Specific therapy with trichinocidal drugs causes a rise in antibody titres, which persist in diagnostic values for 6-12 months, and then decrease. Persons with suspicion of trichinosis who received preventive treatment, serological examination is carried out 2-3 weeks after treatment. In patients with trichinellosis, antibodies persist for a long time - up to 2 years or more.
False positive results of the analysis are more often recorded in the acute phase of a number of helminthiases (opisthorchiasis, clonorchiasis, etc.), in connection with which a careful study of the clinical and epidemiological history is necessary for differential diagnosis.
Indications for the appointment of serological tests
- the presence of clinical symptoms (fever of unknown origin, edema of the face, myalgia, eosinophilia, etc.), myocarditis, meningoencephalitis of unknown origin, leukemoid reaction according to eosinophilic type of unclear genesis in patients eating pork, bear, boar and other animals - potential hosts trichinella;
- interpretation of cases of group morbidity by trichinosis (outbreaks) and identification of contact in endemic areas (in non-endemic areas: if there are epidemiological anamnesis indications for eating animal meat - potential owners of trichinella).