Morphometric and phylogenetic study of Haemonchus isolates in small ruminants from mountainous (Lorestan) and plain (Khuzestan) regions of Iran

Abstract

Haemonchus species are among ruminants' important blood-feeding and pathogenic nematodes. This study aimed to determine morphometric and phylogenetic characteristics of Haemonchus spp. isolates from sheep and goats in two different regions of Iran. A total of 340 isolates of adult Haemonchus spp. from the animals of Khuzestan and Lorestan provinces were identified using morphometric and molecular characteristics. Differentiating functions (DF) of male Haemonchus spp. as well as vulvar morphology and flap diversity for female Haemonchus spp. were determined. The twenty-four samples of Haemonchus contortus that showed the most phenotypic differences were analyzed for the sequencing of two genes, ITS-2 and ND4. Since the DF was less than 0.63, all male isolates were H. contortus. The results showed significant differences in some morphometric characteristics of males and females of H. contortus in animals of two regions. H. contortus female worms showed smooth (2–20 %), knobbed (32–65 %), and linguiform (20–66 %) forms as the lowest vulvar morphs and most common vulvar flap types. Phylogenetic and sequence analysis of ITS2 and ND4 sequences revealed the presence of five and three genotypes for all the isolates, respectively. Morphometric and molecular findings in the present study confirmed H. contortus as the only species in small ruminants from two regions of Iran. The morphometric indices of male and female isolated worms of H. contortus were significantly different concerning the species of animal (goat and sheep) and the geographical region. This study showed that ND4 is more valuable for studying the diversity and phylogeny of H. contortus than ITS2. In this study, there was no correlation between genotypes of different isolates and morphological characteristics, indicating variations in genotypes did not appear to affect the phenotype of H. contortus.