We have investigated specific immune responses in BALB/c mice with experimentally induced secondary hydatidosis. Following intraperitoneal inoculation of brood capsules containing Echinococcus granulosus-protoscoleces, the course of the infection was followed for 513 days. The sera of the mice were screened for the presence of a number of cytokines, and for specific antibodies. During the first 129 days of infection, high levels of cytokines TNF alpha, IL-alpha, IFN gamma, IL-6, and IL-10 and specific IgG1 and IgG3 isotypes were detected, as compared to uninfected controls. The levels of IgM and IgG2a were slightly increased following infection, and remained elevated throughout the period of observation. The levels of IL-1 alpha and specific immunoglobulin of all isotypes except IgM and IgG2a, were significantly decreased 103 days post infection (p.i.), whereas TNF alpha was sharply decreased 129 days p.i. During the period of 129 to 209 days of infection there was an increase in secreted IL-10, and a slow decrease in the levels of IL-6 and IFN gamma. Levels of IgM, IgG, IgG1, and IgG2a plateaued during this period, whereas IgG3 and TNF alpha showed a peak at day 190 p.i. These data suggest the induction of Th2 antibody-mediated immunity with a parallel expansion of Th1-mediated inflammatory responses as important mechanism of host defence against the metacestode.

Faecal specimens randomly taken from 232 healthy dogs living in the area of Thessaloniki were screened for internal parasites. In 39·2% of the examined dogs excretion of Sarcocystis bovicanis (1·3%), Isospora ohioensis/burrowsi (3·9%), Giardia lamblia (0·8%), Hammondia heydorni (0·4%), Dicrocoelium dendriticum (0·8%) Diplopylidium nolleri (0·4%), Joyeuxiella pasqualei (0·8%), taeniids (0·4%), Toxocara canis (22·4%), Toxascaris leonina (1·3%), Uncinaria stenocephala (3·0%), Trichuris vulpis (2·6%), Spirocerca lupi (0·4%), or Linguatula serrata (0·4%) was detected. The overall rate of infection did not show any significant difference concerning sex or age. T. canis, however, was significantly more often found in the youngest age group (1–3 months).

Blood samples from 50 dogs with episodic weakness and 50 clinically normal dogs, all belonging to hunting breeds, were examined for microfilariae using the modified Knott's method. The prevalence of microfilaraemia in dogs belonging to the episodic weakness group was 10% for Dirofilaria immitis, 30% for Dirolfilaria repens and 8% for Acanthocheilonema reconditum. In the clinically normal group, the figures were 14% for Dirofilaria repens and 4% for Acanthocheilonema reconditum. The overall percentage of dogs with microfilaraemia in the episodic weakness group was 44 and that of the clinically normal group 16, with a statistically significant difference (P<0.01). The prevalence of microfilaraemia due to the nonpathogenic filarial species (Dirofilaria repens, Acanthocheilonema reconditum) was 34% and 16% for the episodic weakness group and the clinically normal dogs, respectively, with no significant difference.

Hydatidosis is a usually asymptomatic chronic disease. In most patients who undergo surgery, hydatidosis is not resolved due to high recurrence rate. However, long-term treatment with albendazole has been found to have a significant efficacy that has been further improved when albendazole is combined with praziquantel and fat-rich diet. In this study a retrospective evaluation of the outcome of hydatidosis in 70 patients, was performed. In group A, a combined chemotherapy of albendazole plus praziquantel was given after surgical removal of cysts. In group B chemotherapy alone was administered without surgery. Sera of all patients were assayed for IgG, IgM, IgA and IgE antibodies by ELISA. In addition, ultrasonography (US) and/or computerized tomography (CT) scans were performed every 3 months for 18 months, and then, each year until the end of follow-up. The difference between the two kinds of treatment used in the present study was found to be not significant, nor was the difference of the shrinkage and extended calcification of the HCs between the two groups. However, the difference of the shrinkage of the HCs of more than 80%, as well as the extended calcifications of the cysts between the two groups were found to be statistically significant. In all patients high levels of IgG and IgA were detected, while IgE in group A and/or IgM in group B were marginally detected above the background level throughout the study. Level of IgG was strongly fluctuated and significantly decreased at 11.7 years after the end of chemotherapy, or at 8.5 years after relapses in group A, while was dramatically decreased at 3.6 years after the termination of chemotherapy in group B. Relapses occurred in 11.4% of patients within the first six months after end of chemotherapy. After additional chemotherapy with albendazole for 3–6 months, all of them were considered cured at 8.5 years of follow up.

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