Molecular Identification of Diphyllobothrium latum from a Pediatric Case in Taiwan

Abstract

Human diphyllobothriasis is a parasitic disease caused by ingestion of larvae (plerocercoids) in raw or undercooked fish and commonly found in temperate areas. Rare cases were reported in tropical or subtropical areas especially in children. The first documented case of pediatric diphyllobothriasis in Taiwan had been reported 11 years ago. Here, we report another 8-year-old girl case who presented with a live noodle-like worm hanging down from her anus, with no other detectable symptoms. We pulled the worm out and found the strobila being 260 cm in length. Examination of gravid proglottids showed that they were wider than their lengths, containing an ovoid cirrus sac in the anterior side and the rosette-shaped uterus. Eggs extracted from the uterus were ovoid and operculated. Diphyllobothrium latum was confirmed by molecular analysis of the mitochondrial DNA cytochrome c oxidase subunit 1 (cox1) gene. The girl was treated with a single oral dose of praziquantel, and no eggs or proglottids were observed from her stool in the subsequent 3 months. The reemergence of human diphyllobothriasis in non-endemic countries is probably due to prevalent habit of eating imported raw fish from endemic areas. This pediatric case raised our concern that human diphyllobothriasis is likely underestimated because of unremarkable symptoms.

Diphyllobothriidae

“…Two of 4 cases reported recently acquired the infection in Canada and Russia (Cai et al, 2017). Also, a pediatric case of D. latus was confirmed by molecular analysis and attributed to consumption of imported raw fish from endemic areas (An et al, 2017).…”

“…Due to the globalization of fish trading and to travels and immigration, sporadic cases occurred in no endemic countries and exotic cases (cases with exotic species) occurred in endemic countries (Yera et al, 2006;Wicht et al, 2007Wicht et al, , 2008aWicht et al, , 2008bPaugam et al, 2009;Knoff et al, 2011;Semenas, 2014;An et al, 2017). In 2010, 214 million people lived outside their country of origin, these movements of people contributing to the displacement of foodborne parasites to different regions of the world, as evidenced by example in Dibothriocephalus spp.…”