General considerations

Host-parasite interaction

GENERAL COMMENTS

With rare exceptions (e.g. Hymenolepis nana) a cestode makes contact with the tissues of at least two different hosts during its life cycle. The degree of immunological response by each host is related to three main factors: (a) the nature of the tissue site invaded, (b) the intimacy of the host'parasite contact, and (c) the stage of development of the cestode, i.e. whether adult or larva. For example, in the case of Taenia saginata, the host'parasite contacts established during the life cycle are: (a) the scolex, when attached to the intestine of the definitive (human) host, (b) the oncosphere, during its penetration of the intestinal mucosa of the intermediate (bovine) host and subsequent migration, and finally (c) the developing larva established in its final tissue site.

This chapter will deal with the immune reactions of the host to adult and larval cestodes. Most work has been centred on species of Taenia and Echinococcus in man and domestic animals and on the Hymenolepididae in laboratory animals. In parallel with the remarkable developments in recombinant DNA technology (see Chapter 6) which holds out the tantalising possibilities of producing parasite vaccines – there has been an explosive interest in attempts to develop vaccines against cestodes of medical, veterinary or economic importance, so far without significant success (p. 301).