Abstract

Measurement of lymphocyte blastogenesis and antibody production were used to determine the effect of a benzimidazole anthelmintic on the immune response. Both parasitized and parasite-naive (n=12) lambs, 6 months of age, were treated with fenbendazole (5mg/kgBW) and compared with untreated control animals. All animals (n=24) were given bovine virus diarrhoea (BVD) vaccine the day following anthelmintic treatment. Heparinised blood samples were collected 0,3,7,14 and 21 days after the anthelmintic treatments. The entire treatment regime was repeated at Day 28. No effects on immunity were apparent after the initial dosage with fenbendazole. However, peripheral lymphocytes from lambs (parasitized and parasite-naive) collected 14 days after the second administration of fenbendazole treatment, had significantly lower stimulation indices compared to control animals, when cultured in vitro with concanavalin A (Con A) (P<0.01), phytohaemagglutinin (PHA), and lipopolysacchride (LPS)(P<0.05). In addition, stimulation to Con A was depressed 7 days after the second treatment. The primary and secondary humoral responses to BVD vaccination, as measured by serum neutralisation titre, were similar among groups. The repeated use of anthelmintics from the benzimidazole group may interfere with immune responsiveness in young sheep.

SJ, Parish, RG McFarlane, AS Familton, and TJ Abell

Proceedings of the New Zealand Society of Animal Production, Volume 56, , 80-83, 1996