The response of Awassi sheep to re-infection with Haemonchus contortus larvae

Abstract

SummaryThe response of Awassi sheep to primary infection with 10000 Haemonchus contortus larvae and subsequent challenge with 20000 larvae was studied. Two types of response to re-infection were observed. The first, characterized by a sharp decline in egg counts, progressive improvement in packed cell volume (PCV) and a marked loss of adult worms and challenge larvae, was considered as self-cure and protection. In the second type of response there was a temporary decline in egg counts, no improvement in PCV and necropsy findings indicated hyperinfection with challenge larvae.