Analysis of nad2 and nad5 enables reliable identification of genotypes G6 and G7 within the species complex Echinococcus granulosus sensu lato

The larval stages of tapeworms in the species complex Echinococcus granulosus sensu lato cause a zoonotic disease known as cystic echinococcosis (CE). Within this species complex, genotypes G6 and G7 are among the most common genotypes associated with human CE cases worldwide. However, our understanding of ecology, biology and epidemiology of G6 and G7 is still limited. An essential first step towards this goal is correct genotype identification, but distinguishing genotypes G6 and G7 has been challenging. A recent analysis based on complete mitogenome data revealed that the conventional sequencing of the cox1 (366 bp) gene fragment mistakenly classified a subset of G7 samples as G6. On the other hand, sequencing complete mitogenomes is not practical if only genotype or haplogroup identification is needed. Therefore, a simpler and less costly method is required to distinguish genotypes G6 and G7. We compared 93 complete mitogenomes of G6 and G7 from a wide geographical range and demonstrate that a combination of nad2 (714 bp) and nad5 (680 bp) gene fragments would be the best option to distinguish G6 and G7. Moreover, this method allows assignment of G7 samples into haplogroups G7a and G7b. However, due to very high genetic variability of G6 and G7, we suggest to construct a phylogenetic network based on the nad2 and nad5 sequences in order to be absolutely sure in genotype assignment. For this we provide a reference dataset of 93 concatenated nad2 and nad5 sequences (1394 bp in total) containing representatives of G6 and G7 (and haplogroups G7a and G7b), which can be used for the reconstruction of phylogenetic networks.

Seasonal fluctuations in prevalence of dog intestinal parasites in public squares of Mar del Plata city, Argentina and its risk for humans

The aim of this work is to analyze whether there is a seasonal prevalence of parasites in dog feces from public squares in Mar del Plata city, Argentina, and to evaluate the climatic conditions that promote the development of parasites and allow the transmission to people. The study was performed in 21 squares from June 2001 to May 2002. Samples were processed by the Willis technique. Differences in prevalence of parasites were examined for significance by the Chi-square test. Climatic data were obtained from the Library of the National Meteorological Service of Argentina. Total parasitic prevalence was higher in winter than in summer. The prevalence of Ancylostoma spp. was higher in the summer-autumn period. For Toxocara canis, the prevalence was higher in winter whereas for Trichuris vulpis, it was higher in winter, spring and summer. This work shows high prevalence of total parasites throughout the year. For Ancylostoma spp., summer and autumn might be the seasons with higher sanitary risk. On the other hand, T. canis could present the higher risk to people in winter and, T. vulpis, would be transmitted throughout the whole year. The seasonal variation in prevalence of dog parasites results in continuous exposure to people visiting the squares, not only Mar del Plata residents but also tourists from other regions of Argentina and the world, with at least one species of parasite with sanitary risk.

In vitro and in vivo effects of flubendazole on Echinococcus granulosus metacestodes

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.