Dr. Murai Éva szerk.: Parasitologia Hungarica 11. (Budapest, 1978)

over the IHAT for seroepidemiologic studies (VARELA-DIAZ et al.

, 1976). For maximum sensitivity and specificity, the use of a companion test is recommended. The recent literature is reviewed in Table 2. Latex test (LAT) Because of the simplicity, stability, and specificity of the LAT, the technique has been used both for diagnosis and epidemiologic studies. GUISANTES and VARELA-DIAZ (1975c) recommend the LAT as a screening procedure and recommend that the positive specimens be confirmed by a more specific technique such as immunoelectrophoresis (IEP) or double diffusion in gel (DDG). There are, however, inherent difficulties in the use of the LAT. The latex particles must be standardized to size and chemical composition. The specificity of the test also appears to vary from country to country. Thus in Argentina, the specificity is satisfactory and the test has been recommended for seroepidemiologic screening, but in Egypt, high levels of nonspecific cross reactivity with the sera of patients with schistosomiasis have been reported (BOTROS et al.

, 1973). Russian workers have used the technique extensively. The recent literature is reviewed in Table 3. Bentonité flocculation test (BFT) The BFT, like the LAT, is technically uncomplicated once one has become experienced in preparing the particles and reading the test. It is a test of low reactivity (KAGAN, 1974) and is therefore excellent as a companion test with a technique of high reactivity such as IHAT. For this reason, the IHAT and BFT are used for diagnosis of hydatid infection in the writer's laboratory. Relatively little has been published on the test in recent years. KNIERIM et al. (1971) compared the BFT with the IHAT and found the former to be less sensitive. In Egypt, BOTROS et al. (1975) found the BFT to be more specific than the IHAT. MAHAJAN and CHITKARA (1975) evaluated the BFT, IHAT, and IDT in 50 normal individuals and 44 persons with hydatid disease. The nonspecific serologic response with the normal sera was 14% and 8% and 16% for the BFT IHAT and IDT, respectively. With persons with hydatid disease, the sensitivity of the BFT was 91%; of the IHAT, 86%; and of the IDT, 73%. Immunofluorescence test (IFT) Because the IFT is technically difficult to perform and because other equally sensitive and specific tests are available, the IFT has not been widely used in the diagnosis of hydatid disease. The technique, however, offers certain advantages that make it attractive for diagnosis and postoperative evaluation. The use of class-specific immunoglobulin conjugates for the detection of IgM and IgG is a plus for this method. The rapid decline in antibody titer within a year after a cyst is removed was carefully evaluated by AMBROISE-THOMAS (1976). The recent literature is reviewed in Table 4. Enzyme-linked immunosorbent assay (ELISA) A new technique employing enzymes conjugated to antibody or antigen to detect and measure antigens or antibodies, respectively, is finding wide application in the diagnosis of parasitic diseases (VOLLER et al., 1976). FARAG et al. (1975), working in France, employed whole and purified hydatid antigens and evaluated the test with sera from 43 patients with proven hydatid disease. The purified antigen gave both more sensitive and specific results than whole hydatid fluid antigen. Whole hydatid fluid antigen gave nonspecific results with sera from patients with taeniasis, schistosomiasis, and fascioliosis

. The purified "Band 5" antigen of BOUT et al. (1974) gave no nonspecific results. CAPRON et al. (1975) reviewed the use of ELISA in parasitic diseases. The ELISA technique combines the sensitivity of radioimmunoassay with the technical simplicity of the IHAT. With purified or stage-specific antigens, the technique is most sensitive and specific. The technique will certainly play an important role in the immunodiagnosis of parasitic diseases and warrants further evaluation for the diagnosis of hydatid infection. 32