Haemonchus contortus, an obligatory haematophagus worm infection in small ruminants: Population genetics and genetic diversity.

ABSTRACT

Haemonchus contortus, a stomach worm, is prevalent in ruminants worldwide. They particularly hamper profitable small ruminant production. Here, we estimate the genetic variation of H. contortus collected from slaughtered goats and sheep from various geographic zones of Bangladesh using multiple genes. To perform this, adult parasites were isolated from the abomasum of slaughtered animals (sheep and goats). Among them, 79 male H. contortus were identified by microscopy. Following the extraction of DNA, ITS-2 and cox1 genes were amplified and subsequently considered for sequencing. After alignment and editing, sequences were analyzed to find out sequence variation, diversity pattern of genes, and population genetics of isolates. Among the sequence data, the analyses identified 19 genotypes of ITS-2 and 77 haplotypes of cox1 genes. The diversity of nucleotides was 0.0103 for ITS-2 and 0.029 for cox1 gene. The dendogram constructed by the genotype and haplotype sequences of H. contortus revealed that two populations were circulating in Bangladesh without any demarcation of host and geographic regions. Analysis of population genetics demonstrated a high flow of genes (89.2 %) within the population of the worm in Bangladesh. The Fst value showed very little amount of genetic difference among the worm populations of Bangladesh but marked genetic variation between different continents. The findings are expected to help explain the risks of anthelmintic resistance and the transmission pattern of the parasite, and also provide a control strategy against H. contortus.