ABSTRACT
N early every verteb ra te is infected w ith a parasite at som e stage o f its life. M any o f the parasites are host-specific. The parasites o f m an and dom estic anim als tend to be the m ost w ell know n and the m ost w idely d is tribu ted and are the parasites mainly investigated by parasitologists. In this section there are descrip tions o f som e o f these parasites, described in relation to the num ber o f hosts that they infect during the ir life cycle. The parasites using only one host during their life-cycle are considered to have a d irec t life-cycle; and those w ith m ore than one host are described as having ind irec t life-cycles.
