The taxonomic status of Echinococcus, an important zoonotic cestode genus, has remained controversial, despite numerous attempts to revise it. Although mitochondrial DNA (mtDNA) has been the source of markers of choice for reconstructing the phylogeny of the genus, results derived from mtDNA have led to significant inconsistencies with earlier species classifications based on phenotypic analysis. Here, we used nuclear DNA markers to test the phylogenic relationships of members of the genus Echinococcus. The analysis of sequence data for 5 nuclear genes revealed a significantly different phylogeny for Echinococcus from that proposed on the basis of mitochondrial DNA sequence data, but was in agreement with earlier species classifications. The most notable results from the nuclear phylogeny were (1) E. multilocularis was placed as basal taxon, (2) all genotypes of Echinococcus granulosus grouped as a monophyletic entity, and (3) genotypes G8 and G10 clustered together. We conclude that the analysis of nuclear DNA data provides a more reliable means of inferring phylogenetic relationships within Echinococcus than mtDNA and suggest that mtDNA should not be used as the sole source of markers in future studies where the goal is to reconstruct a phylogeny that does not only reflect a maternal lineage, but aims to describe the evolutionary history at species level or higher.

No abstract

G.M. Denegri, 1993. Review of oribatid mites as intermediate hosts of tapeworms of the Anoploceph',tlidae. Exp. Appl. Acarol., 17:567-580

No abstract

The aim of the present work was to determine the efficacy of flubendazole (FLBZ) against Echinococcus granulosus metacestodes by using in vitro and in vivo models. Groups of 50 microcysts developed in vitro, and groups of 10 peritoneal cysts were obtained from Balb C mice with experimental secondary infections of 8 months. The cysts were placed in Leighton tubes containing 10 ml of culture medium. FLBZ was added to the medium resulting in final concentrations of 5 and 1 microg/ml for mycrocysts treatment and 10, 5, and 1 microg/ml for murine cysts treatment. In vivo treatment was performed on 20 mice that developed an experimental secondary hydatid disease over a period of 11 months. FLBZ was given (1.5 mg/kg) by the oral route once a day for 50 days. A loss of turgidity was detected in all in vitro drug treated cysts irrespective of the drug concentration or parasite origin. Inspection of treated cysts by scanning electron microscopy (SEM) revealed that the germinal layer lost it characteristic multicelular structure. These results were confirmed on the ultrastructural level by transmission electron microscopy (TEM), treated metacestodes had undergone considerable degenerative changes after the in vitro treatment. The results obtained after the in vivo treatment with FLBZ showed no significant difference between the control and treated groups related to the weight of cyst masses. However, the ultrastructural study at TEM of cysts that developed in mice from the treated group revealed alterations in the germinal layer with the presence of numerous vacuoles. With regard to the ultrastructural study at SEM, only cellular debris of the germinal layer could be seen. In conclusion, the data obtained clearly demonstrate that in vitro and in vivo treatment with FLBZ is effective against E. granulosus metacestodes.

No abstract

The aim of the present work was to determine the in vitro protoscolicidal effect of flubendazole (FLBZ) against Echinococcus granulosus. Protoscoleces of E. granulosus were incubated with FLBZ at concentrations of 10, 5 and 1 microg/ml. The first signs of FLBZ-induced damage were observed 3 days post-incubation. A clear protoscolicidal effect, reducing the vitality of protoscoleces to 35.6+/-0.7%, was observed after 18 days of incubation. After 25 days of FLBZ incubation (5 microg/ml), the percentage of vital protoscoleces was 13.9+/-5.9%. Protoscolex mortality was 100% (10 and 1 microg/ml) and 0.7+/-0.7% (5 microg/ml) after FLBZ incubation for 30 days. Results of vitality tests were consistent with the tissue damage observed at the ultrastructural level. The primary site of damage was the tegument of the parasite. The morphological changes included contraction of the soma region, formation of blebs on the tegument, rostellar disorganization, loss of hooks and destruction of microtriches. The data reported in this article demonstrate a clear in vitro effect of FLBZ against E. granulosus protoscoleces.

The need to identify improved therapy against cystic echinococcosis (CE) has motivated pharmacology-based research. The comparative pharmacological performances of the benzimidazole compounds flubendazole (FLBZ) and albendazole (ABZ) were addressed here. The goals of the work were as follows: (i) to evaluate the ex vivo activities of FLBZ, ABZ, and their respective metabolites against Echinococcus granulosus protoscoleces, (ii) to compare the plasma and cyst disposition kinetics for the two drugs in infected mice, and (iii) to compare the clinical efficacies of FLBZ and ABZ against CE in mice. For the ex vivo study, E. granulosus protoscoleces were incubated with FLBZ, reduced FLBZ (R-FLBZ), ABZ, and ABZ-sulfoxide (ABZSO) (10 nmol/ml). Protoscolex viability was monitored by the methylene blue exclusion test and scanning electron microscopy (SEM). For the pharmacokinetic study, BALB/c mice with CE were allocated to two different groups and orally treated with either FLBZ or ABZ (5 mg/kg of body weight), both formulated as a cyclodextrin-based solution. Blood and cyst samples were taken up to 12 h posttreatment and analyzed by high-performance liquid chromatography (HPLC). For the efficacy study, CE-infected BALB/c mice were divided into three groups: the unmedicated control group and the FLBZ-and ABZ-treated groups. Oral treatments were performed twice a day during 25 days. After treatment, all animals were killed and the weight of the cysts was recorded. Loss of protoscolex viability was observed after drug incubation. FLBZ was detected in plasma (area under the concentration-versus-time curve [AUC] ‫؍‬ 1.8 g ⅐ h/ml) and cysts (AUC ‫؍‬ 0.3 g ⅐ h/g) collected from treated infected animals. Conversely, ABZSO was the only active molecule measured in plasma (AUC ‫؍‬ 4.4 g ⅐ h/ml) and cysts (AUC ‫؍‬ 1.5 g ⅐ h/g) after ABZ treatment. FLBZ induced a 90% reduction in cyst weight in comparison to those collected from untreated control mice (P < 0.05). However, no differences in cyst weight were observed between the ABZ-treated (8.2 g) and unmedicated control (10.5 g) groups. Due to these results, we consider flubendazole to have great potential to become a drug of choice in the treatment of cystic echinococcosis.