Morphological and molecular characterization of Haemonchus contortus (Rudolphi, 1803) Cobb, 1898 (Nematoda: Trichostrongyloidea) from sheep, Ovis aries in Egypt based on the second internal transcribed spacer of ribosomal DNA

A total of 562 worms (392 females and 170 males) of H. contortus were collected from abomasa of 70 sheep, Ovis aries slaughtered in Basateen Automated Slaughterhouse, Cairo. Adult male worm, 17.00±0.75 mm long, was smaller than adult female, 28.09±2.86 mm long. Male characterized by having a caudal copulatory bursa at the posterior end, while female characterized by having a vulva that located at the third body length from tail and may or may not be guarded by a cuticular inflation (vulvar flap). According to female vulvar flap characteristic, there were three morphotypes: linguiform (L) (39.5%), knobbed (47.0%) and smooth (13.5%) vulvar flaps. Further classification of the linguiform type of the female vulvar flap revealed the presence of four subtypes: Linguiform A (LA) (60.0%), Linguiform B (LB) (10.3%), Linguiform C (LC) (24.5%) and Linguiform I (LI) (5.2%). Molecular investigation using sequencing of second internal transcribed spacer of ribosomal DNA (ITS-2) revealed that male and each female genotypic sequence was almost identical (99 ? 100%). Evolutionary divergence over all sequence pairs was 0.006 among ITS-2 sequences.