Factors associated with the hatchability of Haemonchus species eggs and molecular identification of Haemonchus contortus

Abstract

Haemonchus species is a common parasitic nematode infecting all ruminants and causing significant economic losses in developing countries. Accurate and reliable identification of various Haemonchus species and their molecular epidemiology is essential to formulate effective control strategies against Haemonchosis. The present study was carried out to identify larval stages of H. contortus in goats and sheep using morphological features and Polymerase chain reaction. A total of 400 abomasa were collected from different abattoirs for parasitological examination. Only female worms were stored for egg isolation. The eggs were collected by macerating the whole female worms with adequate phosphate buffer saline (PBS) using a sterile mortar and pestle followed by filtering through a sieve. The collected eggs were counted by the modified McMaster technique and incubated in different culture media such as phosphate-buffered saline (PBS), normal saline (NS), tap water (TW), and distilled water (DW). The highest hatchability was obtained at PBS (57%) followed by NS (43%) and TW (35%) on the fourth day of incubation at around neutral pH (7) and a temperature of 29°C. Distilled water, acidic (pH < 5) or alkaline (pH > 8) pH, and high temperature (>35°C) suppressed the normal hatching rate. Different larval stages were morphologically identified according to their body length, tail and diameter in um, mouth cavity, and esophageal structure. 5-7% blood sera or glucose enhanced the hatchability up to 58.33%, and other growth enhancers showed no favorable effects. The amplification of 265 bp from ITS-2 of rDNA of H. contortus was successfully conducted to facilitate their molecular identification.