Basic Problems in Serological Diagnosis of Cystic Echinococcosis

Abstract

Cystic echinococcosis (CE), which occurs in rural areas during most seasons, is an important public health problem in Turkey. Many challenges regarding both diagnosis and treatment of this disease have not yet been overcome, and despite significantly increas-ing patient care costs, surgical treatment remains the main option. Confirmation of diagnosis is usually performed by serological tests based on the detection of serum antibodies against crude parasitic extracts (hydatid fluid, HF); however, HF contains cross-re-active antigens that lead to false-positive results, indicating other parasitic and nonparasitic diseases. Moreover, certain patients are serologically negative for HF, despite suffering from CE, likely due to cyst stage, number, and size. The existing insensitive and nonspecific tests have been replaced with indirect hemagglutination test (IHAT), enzyme-linked immunosorbent assay (ELISA), and immunoblotting (IB) in recent years. As a result of the evident diagnostic problems, the World Health Organization/World Animal Health Organization recommendations were based on a sequential screening and confirmatory test model. The use of ELISA, IHAT, latex agglutination tests (LAT), immunofluorescence antibody test, and immunoelectrophoresis is recommended for primary screening. The accepted serological screening tests are IHAT, IFA, and ELISA in Turkey, with the Turkish Ministry of Health, Public Health Agency recommending that at least two serological screening tests are used to diagnose patients with CE, followed by confirmation using IB.In the present review, the laboratory tests used in the diagnosis of CE and their limitations and diagnostic algorithms are explained with reference to the current literature.