<p>Killer whales are top predators in most marine ecosystems and impact the populations of common prey, such as <span class="taxon">Phocidae</span> and <span class="taxon">Otariidae</span> in breeding areas. Killer whales are host to some endoparasites and ectoparasites. They are host to killer whale lice (<span class="taxon">Cyamus orcini</span>), trematodes (<span class="taxon">Fasciola skiranini</span>), cestodes (<span class="taxon">Trigonocotyle spasskyi</span>), and nematodes (<span class="taxon">Anasakis simplex</span>).</p>  <p>A disease that affects killer whales and is often studied is toxoplasmosis (<span class="taxon">Toxoplasma gondii</span>). While this parasite is often benign, it can have serious and fatal effects.<span> (Chadwick, 2001; Endoh et al., 2004; Estes et al., 1998; Heyning and Dahlheim, 1988; Mann et al., 2000)</span></p>