Distribution and prevalence of <i>Opisthorchis viverrini</i>, cholangiocarcinoma, and <i>Bithynia</i> spp. snails in Thailand.

<p>At present, three species of <i>Bithynia</i> act as intermediate hosts for <i>O. viverrini</i>, and their distribution differs all over Thailand. <i>B. siamensis goniomphalos</i> is located in northeast Thailand (thick border), where the prevalence of <i>O. viverrini</i>–associated cholangiocarcinoma (CCA) is highest; <i>B. funiculata</i> specifically distributes in north Thailand; and <i>B. siamensis siamensis</i> is mainly found in central and north Thailand, and rarely in the south <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002284#pntd.0002284-Sripa1" target="_blank">[2]</a>, <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002284#pntd.0002284-Sripa3" target="_blank">[18]</a>–<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0002284#pntd.0002284-Petney1" target="_blank">[20]</a>.