Ancylostoma ceylanicum, novel etiological agent for traveler’s diarrhea—report of four Japanese patients who returned from Southeast Asia and Papua New Guinea

• Published in: Tropical Medicine and Health
• Main Authors: Masahide Yoshikawa, Yukiteru Ouji, Nobuyasu Hirai, Fukumi Nakamura-Uchiyama, Minoru Yamada, Naoki Arizono, Naoaki Akamatsu, Takaharu Yoh, Daisuke Kaya, Toshiya Nakatani, Eiryo Kikuchi, Yuichi Katanami, Kimitoshi Satoh, Ryosuke Maki, Yusuke Miyazato, Yuichiro Oba, Kei Kasahara, Keiichi Mikasa
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2018
• Subjects: Ancylostoma ceylanicum; Soil-transmitted helminth; Imported parasitosis; Southeast Asia; Papua New Guinea; Traveler’s diarrhea; Arctic medicine. Tropical medicine; RC955-962; Arctic
• Online Access: https://doi.org/10.1186/s41182-018-0087-8; https://doaj.org/article/901897fd87eb4b3798b3644d76f18142

Abstract Background Countries in the Southeast Asia region have a high prevalence of soil-transmitted helminth, such as roundworm, whipworm, and hookworms [Ancylostoma duodenale, Necator americanus, Ancylostoma ceylanicum]. Recent molecular-based surveys have revealed that A. ceylanicum, a zoonotic hookworm, is likely the second most prevalent hookworm species infecting humans in that part of the world, while others have noted that this infection is an emerging public health risk not only for indigenous people but also for visitors from other countries. Case presentation We recently encountered four cases of A. ceylanicum infection in Japanese individuals who returned from Southeast Asia and Papua New Guinea. Case 1 was a 25-year-old male who stayed in a rainforest in Malaysia for 4 weeks, where he developed abdominal pain and diarrhea in the third week. Eleven adult worms (five males, six females) were expelled after treatment with pyrantel pamoate and identified as A. ceylanicum based on morphological characteristics and DNA sequences of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene. Case 2 was a 26-year-old male who spent 2 years as an overseas cooperation volunteer for agriculture in Papua New Guinea. He did not note any symptoms at that time, though eggs were detected in feces samples at a medical check-up examination after returning. Although collection of adult worms was unsuccessful, DNA analysis of the eggs for cox1 and the ribosomal internal transcribed spacer (ITS)-1 and ITS-2 genes demonstrated that they were A. ceylanicum. Case 3 was a 47-year-old male who spent 1 month in a rural village in Lao People’s Democratic Republic and began suffering from watery diarrhea from the third week. A total of nine adult worms (three males, six females) were collected by endoscopic procedures and following treatment with pyrantel pamoate. Morphological examination and molecular analyses of the cox1 gene showed that they were A. ceylanicum. Case 4 was a 27-year-old male who participated in group ...