Haemozoin Visualization in Haemonchus contortus

The collected parasitic L4s and adult H. contortus were thoroughly washed using sterile PBS solution. The samples were anesthetised by 1% levamisole and then the haemozoin-like pigement was observed by a light microscope (Zeiss Primovert iLED, Gttingen, Germany). To identify the ferric iron in the haemozoin, these L4s and adult worms were stained by a ferric iron stain kit (Solarbio, Beijing, China) according to the manufacturer’s instructions. Briefly, these parasites were fixed with 4% paraformaldehyde for 24 h and stained for 24 h. After the worms were washed and dehydrated, they were carefully transferred to a glass slide and observed using Zeiss light microscopy.