Abstract
Haemonchus contortus is a hematophagous nematode causing substantial economic losses to the livestock industry worldwide. This study aimed to investigate epidemiological determinants, morphometrics, and phylogenetic relationships of Haemonchus in small ruminants (goats and sheep) of Malakand division, Pakistan. Fecal samples (n=878) were randomly collected across four seasons (January to December, 2024) from six districts of the Malakand division to evaluate the prevalence and risk factors. Abomasa from 100 small ruminants were collected for morphometric and phylogenetic studies. Morphological identification was followed by DNA extraction from the adult worms and subsequent PCR amplification of the Cox-1 genetic marker. The overall prevalence of Haemonchus was 25.17 % (221/878), with significantly higher infection rates in small ruminants with poor health 36.19 % (38/105, P= 0.0003), those >5 years old 28.82 % (89/318, P= 0.0391), and untreated small ruminants 29.08 % (171/588, P= 0.0004), based on Chi-square test (P < 0.05), using bivariate analysis. Morphometric analysis revealed that the Haemonchus eggs were oval with an average length of 80.98 μm and a width of 45.04 μm. Male worms measured 11.9 – 13.8 mm long, while females ranged from 15 – 23.8 mm. Phylogenetic analysis based on the Cox-1 gene revealed a close genetic relationship between isolates from the Malakand division and those from Bangladesh, Pakistan, and Iran. Furthermore, the study identified two distinct haplotypes, providing further insights into the genetic variability within Haemonchus populations. This study highlights the significant burden of Haemonchus infections in the region, emphasizing health status, treatment, and age as key risk factors. The findings of this study provide a foundation for the development of effective control strategies against Haemonchus infections in small ruminants.