[Compared parasitic infection of Ligula intestinalis (Cestoda: Diphyllobothridae) in Cyprinidae species: Rutilus rubilio and Scardinius erythrophthalmus in two dam reserves in Tunisia]. / Infestation compaéee de Ligula intestinalis (Cestoda: Diphyllobothridae) chez deux poissons Cyprinidés : Rutilus rubilio et Scardinius erythrophthalmus dans deux retenues de barrages en Tunisie.

Monitoring quantitative parameters of parasitism by ligula intestinalis (Cestoda: Diphyllobothridae) was performed by examining 516 fish belonging to two introduced freshwater species: Rutilus rubilio (350 individuals) and Scardinius erythrophthalmus (166 individuals). These fish were collected in two dam reserves in Tunisia, Sidi Salem and Nebhana. The analysis of the aquatic bird's composition in these two reserves revealed the existence of piscivorous bird species that were previously reported as final host of Ligula. Monitoring the bird's composition highlighted higher relative abundance and frequency in Sidi Salem than in Nebhana dam reserve. The analyses of the prevalence, mean intensity and abundance of the parasite revealed the most important values in roach, Rutilus rubilio which seems to be the preferential second intermediate host of the parasite Ligula intestinalis in these environments. Comparative analysis of parasitism in both explored sites suggests that Ligula intestinalis presents two different strategies of infestation. In Sidi Salem reserve, which is larger than Nebhana and containing on important and diversified piscivorous species, the parasite infects a maximum of host individuals with low parasite mean intensity values. However, at Nebhana, which is a smaller reserve, the parasite infects fewer individuals than Sidi Salem but with higher mean intensity. The highest prevalence values were recorded in large size classes of roach species in Sidi Salem reserve.

Genetic differences between Tunisian camel and sheep strains of the cestode Echinococcus granulosus revealed by SSCP.

Ovine and dromedary Echinococcus granulosus isolates from Tunisia were identified as G1 and G6 strains based on polymorphism of the mitochondrial cytochrome C oxydase CO1. Single strand conformation polymorphism (SSCP) was used in order to examine the genetic variation within and between Tunisian G1 and G6 strains and to estimate the extent of selfing. The dromedary isolates are genetically distinct from sheep isolates (high value of genetic variation between populations: Fst= 0.46). No significant deficiency in heterozygotes was found in sheep isolates, whereas heterozygote deficiency (suggesting selfing) was found in a limited number of camel isolates.