A comparison of the effects of dialysed and non-dialysed transfer factor preparations on Haemonchus contortus infections in young lambs.

Significant reductions in worm burdens were achieved in lambs treated with dialysed transfer factor and challenged with 10,000 Haemonchus contortus larvae, when compared with challenged control animals. Non-dialysed transfer factor, from the same leucocyte pool, produced no protection, but was successful in reducing worm burdens when given after a primary infection of 1,000 H. contortus larvae with subsequent challenge of 10,000 larvae. While the results confirmed the previously reported inconsistencies of transfer factor activity, the histological abomasal changes in all the dialysed and non-dialysed transfer factor treated groups, irrespective of measurable effects on worm burdens, were consistent and corresponded to immediate type hypersensitivity responses. The similarity of these responses with self cure in haemonchosis and the possibility of genetic factors influencing the quantitative expression of protection to the effects of transfer factor treatments is discussed.