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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
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Arc-C-5 in Countercurrent electrophoresis of Serum is diagnostic of -
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The correct answer is  Cystic echinococcal disease (Echinococcus granulosus). Indirect hemagglutination (IHA), indirect fluorescent antibody (IFA) tests, and enzyme immunoassays (EIA) are sensitive tests for detecting antibodies in serum of patients with cystic disease; sensitivity rates vary from 60% to 90%, depending on the characteristics of the cases. Crude hydatid cyst fluid is generally employed as antigen. At present, the best available serologic diagnosis is obtained by using combinations of tests. EIA or IHA is used to screen all specimens; a positive reaction is confirmed by immunoblot assay or any gel diffusion assay that demonstrates the echinococcal "Arc 5." REF;