{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,3]],"date-time":"2026-04-03T02:28:28Z","timestamp":1775183308523,"version":"3.50.1"},"reference-count":0,"publisher":"American Society of Tropical Medicine and Hygiene","issue":"1","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2022,1,5]]},"abstract":"<jats:title>ABSTRACT.<\/jats:title>\n<jats:p>Here, we report for the first time the snail intermediate host for the <jats:italic>Amphimerus<\/jats:italic> liver fluke, a foodborne trematodiasis. In Ecuador, <jats:italic>Amphimerus<\/jats:italic> of the Opisthorchiidae family, infects humans, cats, and dogs, in the tropical Pacific-coast region. Opisthorchiidae comprising also <jats:italic>Clonorchis sinensis<\/jats:italic>, <jats:italic>Opisthorchis<\/jats:italic> sp., and <jats:italic>Metorchis<\/jats:italic> sp., have complex life cycles involving a definitive and two intermediate hosts. We identified morphologically and investigated the presence and prevalence of <jats:italic>Amphimerus<\/jats:italic> cercaria and DNA in freshwater snails collected in a human-amphimeriasis endemic region in Ecuador, extracted DNA from snail tissue and emerged cercariae, performed real-time polymerase chain reaction (PCR) with the newly developed primers and probe amplifying the <jats:italic>Amphimerus<\/jats:italic> ribosomal internal transcribed spacer 2 (ITS2) region, and sequenced the amplified DNA fragment. We collected 2,800 snails, characterized four species <jats:italic>Aroapyrgus<\/jats:italic> sp., <jats:italic>Melanoides tuberculata<\/jats:italic>, <jats:italic>Biomphalaria cousini<\/jats:italic>, and <jats:italic>Aplexa marmorata<\/jats:italic>, isolated three cercariae morphotypes. Of the 640 snails analyzed by qPCR, only <jats:italic>Aroapyrgus<\/jats:italic> and one of the three cercariae resulted positive, at a 15% infection prevalence. Polymerase chain reaction revealed that the <jats:italic>Aroapyrgus<\/jats:italic> snail and cercaria-morphotype-3 corresponded to <jats:italic>Amphimerus<\/jats:italic>, but not to <jats:italic>C. sinensis<\/jats:italic>, <jats:italic>Fasciola hepatica<\/jats:italic>, or <jats:italic>Paragonimus mexicanus<\/jats:italic>. The sequence of amplified DNA product matched that of human-isolated <jats:italic>Amphimerus<\/jats:italic>. This finding constitutes the first documentation that <jats:italic>Aroapyrgus<\/jats:italic> sp. is the first intermediate host for the <jats:italic>Amphimerus<\/jats:italic> sp. that infect humans in Ecuador. The ITS2\u2013gene PCR and sequencing analysis demonstrated a high prevalence of snail infection and proved useful for detecting the infection in snails, which findings can help the establishment of suitable control programs against transmission in any endemic region of interest.<\/jats:p>","DOI":"10.4269\/ajtmh.21-0697","type":"journal-article","created":{"date-parts":[[2021,10,25]],"date-time":"2021-10-25T12:14:27Z","timestamp":1635164067000},"page":"222-228","source":"Crossref","is-referenced-by-count":3,"title":["Molecular Identification of the Human Pathogen Amphimerus sp. in the Freshwater Snail Aroapyrgus sp. in Ecuador"],"prefix":"10.4269","volume":"106","author":[{"given":"Manuel","family":"Calvopi\u00f1a","sequence":"first","affiliation":[{"name":"1One Health Research Group, Escuela de Medicina, Facultad de Ciencias de la Salud, Universidad de las Am\u00e9ricas (UDLA), Quito, Ecuador;"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Carlos","family":"Bastidas-Caldes","sequence":"additional","affiliation":[{"name":"1One Health Research Group, Escuela de Medicina, Facultad de Ciencias de la Salud, Universidad de las Am\u00e9ricas (UDLA), Quito, Ecuador;"},{"name":"2Ingenier\u00eda en Biotecnolog\u00eda, Facultad de Ingenier\u00eda y Ciencias Aplicadas (FICA), Universidad de las Am\u00e9ricas (UDLA), Quito, Ecuador;"},{"name":"3Programa de Doctorado en Salud P\u00fablica y Animal, Universidad de Extremadura, Extremadura, Caceres, Spain;"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Francisco","family":"Romero","sequence":"additional","affiliation":[{"name":"2Ingenier\u00eda en Biotecnolog\u00eda, Facultad de Ingenier\u00eda y Ciencias Aplicadas (FICA), Universidad de las Am\u00e9ricas (UDLA), Quito, Ecuador;"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Irina","family":"Villacr\u00e9s-Granda","sequence":"additional","affiliation":[{"name":"4Programa de Doctorado Interuniversitario en Ciencias de La Salud, Universidad de Sevilla, Sevilla, Spain;"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jean-Pierre","family":"Pointier","sequence":"additional","affiliation":[{"name":"5PSL Research University, USR 3278 CNRS\u2013EPHE, CRIOBE Universit\u00e9 de Perpignan, Perpignan, France;"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hidekazu","family":"Takagi","sequence":"additional","affiliation":[{"name":"6Department of Microbiology and Immunology, Aichi Medical University School of Medicine, Aichi, Japan;"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hiromu","family":"Sugiyama","sequence":"additional","affiliation":[{"name":"7Department of Parasitology, National Institute of Infectious Diseases, Tokyo, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"2795","container-title":["The American Journal of Tropical Medicine and Hygiene"],"original-title":[],"link":[{"URL":"https:\/\/www.ajtmh.org\/view\/journals\/tpmd\/106\/1\/article-p222.xml","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/www.ajtmh.org\/downloadpdf\/journals\/tpmd\/106\/1\/article-p222.xml","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,1,5]],"date-time":"2022-01-05T12:09:46Z","timestamp":1641384586000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.ajtmh.org\/view\/journals\/tpmd\/106\/1\/article-p222.xml"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,1,5]]},"references-count":0,"journal-issue":{"issue":"1"},"URL":"https:\/\/doi.org\/10.4269\/ajtmh.21-0697","relation":{},"ISSN":["0002-9637","1476-1645"],"issn-type":[{"value":"0002-9637","type":"print"},{"value":"1476-1645","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,1,5]]}}}