Vijayasarathi, M.K.Sheeba, A.Manikkavasagan, I.Sreekumar, C.Dhama, K.TANUVAS2019-07-222019-07-222015-07http://krishikosh.egranth.ac.in/handle/1/5810116147TNV_JII_17(2)_JuL2015_79-85Sheep, called as ‘museum of parasites’, is susceptible to many nematodes. Among the nematodes, Haemonchus contortus is an important voracious blood sucking helminth, which causes alteration in pH of abomasum and blood parameters like PCV. The host produces some immune mechanism against H. contortus to limit the pathogenic effect produced by the parasite. However, the parasite escapes the host immune response in order to survive within the host, which is called ‘evasion’ mechanism.en-USVeterinary ScienceVeterinary ParasitologyArticle