Immunologically based control strategies for ostertagiosis in cattle: where do we stand?

Ostertagia ostertagi is one of the most important gastrointestinal parasites infecting millions of cattle in temperate climate areas. Because infection leads to significant losses in productivity, farmers are pushed, because of the on-going intensification of the livestock production systems, to frequently administer anthelmintics to minimize the exposure of their animals to this parasite. However, whether such approach is sustainable in the long term, especially in an era of emerging drug resistance and global climatic changes, is still a matter of debate. Immunological control of worm infections through vaccination is often put forward as the most rational and cost-effective alternative for anthelmintics to control helminth infections. However, the development of an immunologically based control strategy requires a thorough knowledge of the host-parasite interactions, the immune responses involved and the biology of the parasite itself. The aim of this review is to consolidate information available in these areas, specifically for O. ostertagi, and identify some critical gaps in our current knowledge.