Studies on the Serological Response in Sheep to Naturally Acquired Gastro-intestinal Nematodes

An inverse relationship has been demonstrated between egg counts and antibody titres. This relationship is also evident on a seasonal basis in the “spring rise”. The “spring rise” is preceded by a decrease in the immune status of the sheep and is terminated by a self cure mechanism which establishes a period of protection. The significance of these findings is discussed with regard to the onset and development of the “spring rise”.