We report our experience in the treatment with benzoimidazole carbamates (mebendazole and albendazole) of 337 patients affected by hydatid cysts with different localizations. The treated cysts showed degenerative modifications in 50.6% of the cases after mebendazole treatment and in about 80%o after albendazole treatment. Relapses after therapy were observed in 30%o of the cases; about 95% of the recurring cysts showed good susceptibility to a further cycle of therapy with benzoimidazole carbamates. Side effects observed with either drug were not severe and always reversible, consisting mainly of abdominal pains and increased levels of transaminases in serum. Among the factors that may influence the therapeutic results are the drug employed, the age of the cysts, the age of the patient, and the localization of the cysts and their morphological characteristics. Moreover, it can be hypothesized that each hydatid cyst has an intrinsic sensitivity to benzoimidazole carbamates.

An immunoblot assay was tested to evaluate its ability to diagnose human hydatidosis and to analyse the reactivity of hydatid patients' sera with the subunits of the 2 major Echinococcus granulosus antigens (5 and B). In all, 308 sera were examined: 166 sera from patients with clinically diagnosed hydatidosis, 100 sera from healthy control subjects, and 42 sera from patients with diseases other than hydatidosis. The sensitivity of the method was 90%, as compared to 78% with the immunoelectrophoresis/double diffusion test for antigen 5. No reactivity was found with 15 sera from patients with schistosomiasis, 7 sera from patients with trichinellosis, or 20 sera from patients with non-parasitic diseases. Analysis of serum reactivities showed the presence in all positive sera of antibodies directed against the 39 kDa molecule of the antigen 5 complex. A lower reactivity (55% of all hydatid sera) was observed with the subunits of the antigen B complex.

To assess the participation of the four subclasses of IgG in the humoral response to Echinococcus granulosus infection, we determined total and parasite-specific IgG1, IgG2, IgG3 and IgG4 in sera from 46 patients with hydatid disease using an enzyme-linked immunosorbent assay (ELISA). Parasite-specific IgG subclass antibodies were quantitatively measured by means of standard curves obtained by affinity chromatography. Sera from 35 healthy individuals served as controls. The total component of IgG1, IgG2, and IgG3 showed a slight increase in patients with hydatidosis in comparison to normal control subjects with no significant differences. For the IgG4 subclass, however, a marked elevation was found in the patients group (p = 0.001 by analysis of variance). IgG1 and IgG4 subclasses showed a high anti-echinococcus antibody response, whereas there was a low parasite-specific IgG2 and IgG3 response. Indeed IgG-specific antibodies were found to belong mainly to IgG1 (63%) and to IgG4 (30%) and to a lesser extent to IgG2 (5%) and IgG3 (2%). The percentage of the total serum IgG4 antibodies that were specific for hydatid antigen reached a mean level of 18%, significantly higher than that of any of the other three IgG subclasses (p < 0.001 by Student’s t test). Thus, the continuous antigenic stimulation of hydatidosis may result in an enhanced IgG4 subclass response.

The sonographic appearance of 141 hepatic and abdominal hydatid cysts was studied in 63 patients undergoing therapy with benzoimidazolic compounds. The cysts were evaluated for size, margins of the cyst wall, and echo pattern of cyst contents to establish the response to the drugs. Changes seen on ultrasound (US) scans were classified as decrease in size, detachment of the cyst membrane, and appearance of echogenic material (matrix) in the cyst cavity. These findings, particularly the diffusely hyperechoic pattern, are explained on the basis of the action of the drugs. Twenty-one patients underwent surgery at the end of treatment. The US patterns of treated hydatid cysts are similar to those seen, though more rarely, in cases of spontaneous parasite involution in long-standing hydatidosis.

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