ABSTRACT
A wide range of parasites can infect and affect sheep. These are spread across the spectra of parasitic organisms including protozoa, helminth and arthropod groups. By definition, a parasite will be relying on the host for nutrients and this will have some consequences for the host, although the consequences vary considerably from one parasite to another. This chapter will not be comprehensive but will concentrate on some of the current topical issues with gastrointestinal nematodes (GIN).
