{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,18]],"date-time":"2026-09-18T01:16:13Z","timestamp":1789694173498,"version":"4.0.1"},"update-to":[{"DOI":"10.1371\/journal.pntd.0009277","type":"new_version","label":"New version","source":"publisher","updated":{"date-parts":[[2021,4,6]],"date-time":"2021-04-06T00:00:00Z","timestamp":1617667200000}}],"reference-count":32,"publisher":"Public Library of Science (PLoS)","issue":"3","license":[{"start":{"date-parts":[[2021,3,25]],"date-time":"2021-03-25T00:00:00Z","timestamp":1616630400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["www.plosntds.org"],"crossmark-restriction":false},"short-container-title":["PLoS Negl Trop Dis"],"abstract":"<jats:sec id=\"sec001\">\n<jats:title>Background<\/jats:title>\n<jats:p><jats:italic>Giardia duodenalis<\/jats:italic> is a leading cause of gastroenteritis worldwide. Humans are mainly infected by two different subtypes, i.e., assemblage A and B. Genotyping is hampered by allelic sequence heterozygosity (ASH) mainly in assemblage B, and by occurrence of mixed infections. Here we assessed the suitability of current genotyping protocols of <jats:italic>G<\/jats:italic>. <jats:italic>duodenalis<\/jats:italic> for epidemiological applications such as molecular tracing of transmission chains.<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec002\">\n<jats:title>Methodology\/Principal findings<\/jats:title>\n<jats:p>Two <jats:italic>G<\/jats:italic>. <jats:italic>duodenalis<\/jats:italic> isolate collections, from an outpatient tropical medicine clinic and from several primary care laboratories, were characterized by assemblage-specific qPCR (<jats:italic>TIF<\/jats:italic>, <jats:italic>CATH<\/jats:italic> gene loci) and a common multi locus sequence typing (MLST; <jats:italic>TPI<\/jats:italic>, <jats:italic>BG<\/jats:italic>, <jats:italic>GDH<\/jats:italic> gene loci). Assemblage A isolates were further typed at additional loci (<jats:italic>HCMP22547<\/jats:italic>, <jats:italic>CID1<\/jats:italic>, <jats:italic>RHP26<\/jats:italic>, <jats:italic>HCMP6372<\/jats:italic>, <jats:italic>DIS3<\/jats:italic>, <jats:italic>NEK15411<\/jats:italic>).<\/jats:p>\n<jats:p>Of 175\/202 (86.6%) patients the <jats:italic>G<\/jats:italic>. <jats:italic>duodenalis<\/jats:italic> assemblage could be identified: Assemblages A 25\/175 (14.3%), B 115\/175 (65.7%) and A+B mixed 35\/175 (20.0%). By incorporating allelic sequence heterozygosity in the analysis, the three marker MLST correctly identified 6\/9 (66,7%) and 4\/5 (80.0%) consecutive samples from chronic assemblage B infections in the two collections, respectively, and identified a cluster of five independent patients carrying assemblage B parasites of identical MLST type. Extended MLST for assemblage A altogether identified 5\/6 (83,3%) consecutive samples from chronic assemblage A infections and 15 novel genotypes. Based on the observed A+B mixed infections it is estimated that only 75% and 50% of assemblage A or B only cases represent single strain infections, respectively. We demonstrate that typing results are consistent with this prediction.<\/jats:p>\n<\/jats:sec>\n<jats:sec id=\"sec003\">\n<jats:title>Conclusions\/Significance<\/jats:title>\n<jats:p>Typing of assemblage A and B isolates with resolution for epidemiological applications is possible but requires separate genotyping protocols. The high frequency of multiple infections and their impact on typing results are findings with immediate consequences for result interpretation in this field.<\/jats:p>\n<\/jats:sec>","DOI":"10.1371\/journal.pntd.0009277","type":"journal-article","created":{"date-parts":[[2021,3,25]],"date-time":"2021-03-25T20:34:49Z","timestamp":1616704489000},"page":"e0009277","update-policy":"https:\/\/doi.org\/10.1371\/journal.pntd.corrections_policy","source":"Crossref","is-referenced-by-count":30,"title":["Suitability of current typing procedures to identify epidemiologically linked human Giardia duodenalis isolates"],"prefix":"10.1371","volume":"15","author":[{"given":"Andreas","family":"Woschke","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9196-570X","authenticated-orcid":true,"given":"Mirko","family":"Faber","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Klaus","family":"Stark","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Martha","family":"Holtfreter","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8117-5421","authenticated-orcid":true,"given":"Frank","family":"Mockenhaupt","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joachim","family":"Richter","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Thomas","family":"Regnath","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ingo","family":"Sobottka","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ingrid","family":"Reiter-Owona","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9176-9530","authenticated-orcid":true,"given":"Andreas","family":"Diefenbach","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2809-5542","authenticated-orcid":true,"given":"Petra","family":"Gosten-Heinrich","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8632-2988","authenticated-orcid":true,"given":"Johannes","family":"Friesen","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ralf","family":"Ignatius","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Toni","family":"Aebischer","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2609-9654","authenticated-orcid":true,"given":"Christian","family":"Klotz","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2021,3,25]]},"reference":[{"key":"pntd.0009277.ref001","doi-asserted-by":"crossref","first-page":"335","DOI":"10.1016\/j.meegid.2017.12.001","article-title":"Host specificity in the Giardia duodenalis species complex","volume":"66","author":"SM Caccio","year":"2018","journal-title":"Infect Genet Evol"},{"issue":"1","key":"pntd.0009277.ref002","doi-asserted-by":"crossref","first-page":"110","DOI":"10.1128\/CMR.00033-10","article-title":"Zoonotic potential and molecular epidemiology of Giardia species and giardiasis","volume":"24","author":"Y Feng","year":"2011","journal-title":"Clin Microbiol Rev"},{"key":"pntd.0009277.ref003","doi-asserted-by":"crossref","first-page":"7","DOI":"10.1016\/j.meegid.2018.02.012","article-title":"A novel high-resolution multilocus sequence typing of Giardia intestinalis Assemblage A isolates reveals zoonotic transmission, clonal outbreaks and recombination","volume":"60","author":"J Ankarklev","year":"2018","journal-title":"Infect Genet Evol"},{"issue":"12","key":"pntd.0009277.ref004","doi-asserted-by":"crossref","first-page":"e558","DOI":"10.1371\/journal.pntd.0000558","article-title":"partners. 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