First report of Fasciola hepatica in Equus caballus host species from Tunisia based on the ribosomal internal transcribed spacer regions

Fasciolosis caused by Fasciola spp. (Platyhelminthes: Trematoda: Digenea) is considered the most important helminth infection of ruminants in tropical countries, causing considerable socioeconomic problems. Samples identified morphologically as Fasciola sp. in Equus caballus host species from the city of Tunis (north of Tunisia) were genetically characterized, for the first time, by sequences of the 1st (ITS-1), the 5.8S and 2nd (ITS-2) Internal Transcribed Spacers (ITS) of nuclear ribosomal DNA (rDNA). Comparison of the ITS of the Tunisian samples with sequences of Fasciola spp. from GenBank showed that the specimens examined had sequences identical to those of F. hepatica sequences selected as reference. The nucleotide sequencing of ITS rDNA showed no nucleotide variation in the ITS-1, 5.8S, or ITS-2 rDNA sequences among all F. hepatica samples parasitizing horses from Tunis, versus 2 ITS-2 haplotypes in standard F. hepatica, showing a substitution C/T in position 859, reported previously from Tunisia, Algeria, and Spain. The present study is the first demonstration of the existence of the most frequent haplotype (FhITS-H1) of F. hepatica species in horses from Tunis (north of Tunisia) by the genetic approach using ITS rDNA as genetic marker, providing a foundation for further studies on Fasciola sp. in North African countries.