Evaluation of an enzymatic immunohistochemical technique in human trichinellosis

A comparative study was undertaken between an enzymatic immunohistochemical technique (EIT) developed for the diagnosis of human trichinellosis and the indirect immunofluorescence test (IIF), analysing sera from outbreaks of human trichinellosis in Argentina. The EIT was developed using a biotinylated anti-human gammaglobulin and a preformed macromolecular complex of avidin and biotinylated peroxidase. In both tests, the antigen used consisted of infected rat tissue sections containing muscle larval cysts of Trichinella spiralis. Results showed that the EIT closely correlated with IIF and also allowed diagnosis at an early stage of infection, thus helping to provide effective treatment for the disease. When the test was performed on sera from healthy individuals and those with other parasitic infections, cross-reactions were observed only with sera from patients with toxocariasis (1/8), Chagas' disease (3/17) and four out of 100 healthy individuals. No cross-reactions were observed with sera from patients with toxoplasmosis (0/7) or hydatidosis (0/8). Assay sensitivity was 100% and its specificity 93%. Since it renders no false negative results, EIT is an effective screening tool for detecting infection and should prove to be an important diagnostic technique for trichinellosis in rural areas and for epidemiological surveys.