Eosinophilia and reduced temperature after intradermal injection with 'Haemonchus contortus' larvae correlates with reduced worm infection in vaccinated sheep

Abstract

Breeding resistant sheep as a means of controlling the economic burden of worms on sheep production is a feasible and sustainable option. Understanding immune responses correlated with resistance may allow the development of "easy to measure" markers for breed selection. Intradermal injections can be employed to assess early immune reactivity (4-6 h) or delayed-type hypersensitivity (DTH) at 24-48 h. Previous reports showed that DTH with worm larvae results in eosinophilia (Rothwell et al. 1993), a host immune cell implicated in the killing of 'Haemonchus contortus' third stage larvae (L3) (Balic et al. 2006). Therefore intradermal injections were investigated as a tool to identify correlates of host resistance in unvaccinated and vaccinated animals against gastrointestinal worm, 'H. contortus'.