{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,30]],"date-time":"2026-06-30T19:53:27Z","timestamp":1782849207961,"version":"3.54.5"},"reference-count":55,"publisher":"Public Library of Science (PLoS)","issue":"6","license":[{"start":{"date-parts":[[2026,6,30]],"date-time":"2026-06-30T00:00:00Z","timestamp":1782777600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Institut Pasteur de Madagascar_ Pasteur International joint research Unit-Plague"},{"DOI":"10.13039\/501100003323","name":"ANRS MIE","doi-asserted-by":"crossref","award":["ANRS-23-PEPR-MIE 0002 \u2013 DEBS Plague"],"award-info":[{"award-number":["ANRS-23-PEPR-MIE 0002 \u2013 DEBS Plague"]}],"id":[{"id":"10.13039\/501100003323","id-type":"DOI","asserted-by":"crossref"}]}],"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>\n                      Flea-borne transmission of the plague bacillus,\n                      <jats:italic>Yersinia pestis<\/jats:italic>\n                      , occurs through two regurgitation-based mechanisms. One, called early-phase transmission (EPT), takes place within 24\u201396 hours post-infection through a poorly understood mechanism. The second requires an intrinsic incubation period and relies on the formation of a biofilm obstructing the flea\u2019s proventriculus. Although these mechanisms have been described in different flea species, they have never been characterized in\n                      <jats:italic>Xenopsylla brasiliensis<\/jats:italic>\n                      and\n                      <jats:italic>Synopsyllus fonquerniei<\/jats:italic>\n                      , which are two flea vectors suspected and confirmed to contribute to\n                      <jats:italic>Y. pestis<\/jats:italic>\n                      transmission in Madagascar. Because EPT may facilitate rapid pathogen spread, this study aimed to experimentally assess the ability of both flea species to transmit\n                      <jats:italic>Y. pestis<\/jats:italic>\n                      via EPT.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec002\">\n                    <jats:title>Methodology<\/jats:title>\n                    <jats:p>\n                      Cohorts of starved\n                      <jats:italic>X. brasiliensis<\/jats:italic>\n                      and\n                      <jats:italic>S. fonquerniei<\/jats:italic>\n                      fleas were artificially infected with\n                      <jats:italic>Y. pestis<\/jats:italic>\n                      . From day 1 (D1) to day 4 (D4) post-infection (p.i.), pools of ten infected fleas were fed on sterile mouse blood. After feeding, bacterial loads in both the blood and the fleas were determined by Colony Forming Unit (CFU) counts on blood agar to assess bacterial transmission. Fleas were also observed under a binocular microscope to determine whether the foregut was blocked, as indicated by the presence of fresh blood in the foregut but not in the midgut.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec003\">\n                    <jats:title>Principal findings<\/jats:title>\n                    <jats:p>\n                      The results showed that\n                      <jats:italic>X. brasiliensis<\/jats:italic>\n                      and\n                      <jats:italic>S. fonquerniei<\/jats:italic>\n                      were able to transmit\n                      <jats:italic>Y. pestis<\/jats:italic>\n                      as early as 24 hours p.i., although transmission events were infrequent. No correlation was found between flea bacterial load (ranging from 4.0 x 10\n                      <jats:sup>1<\/jats:sup>\n                      to 4.4 x 10\n                      <jats:sup>5<\/jats:sup>\n                      CFU) and transmission success. Blockage was observed in 1% of\n                      <jats:italic>S. fonquerniei<\/jats:italic>\n                      (D3 and 4 p.i) and 0.75% of\n                      <jats:italic>X. brasiliensis<\/jats:italic>\n                      (D4 p.i.), without detectable transmission by these blocked fleas during the experimental window.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec id=\"sec004\">\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>\n                      This study provides the first experimental evidence that\n                      <jats:italic>X. brasiliensis<\/jats:italic>\n                      and\n                      <jats:italic>S. fonquerniei<\/jats:italic>\n                      can support early-phase transmission of\n                      <jats:italic>Y. pestis<\/jats:italic>\n                      and are capable of developing proventricular blockage under laboratory conditions. These findings refine our understanding of the potential contribution of these flea species to plague transmission dynamics in Madagascar.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.1371\/journal.pntd.0014463","type":"journal-article","created":{"date-parts":[[2026,6,30]],"date-time":"2026-06-30T19:15:39Z","timestamp":1782846939000},"page":"e0014463","update-policy":"https:\/\/doi.org\/10.1371\/journal.pntd.corrections_policy","source":"Crossref","is-referenced-by-count":0,"title":["Experimental evidence of early-phase transmission of Yersinia pestis by Synopsyllus fonquerniei and Xenopsylla brasiliensis"],"prefix":"10.1371","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3766-5324","authenticated-orcid":true,"given":"Ravo","family":"Rakotobe Harimanana","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Florent","family":"Sebbane","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mireille","family":"Harimalala","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2026,6,30]]},"reference":[{"key":"pntd.0014463.ref001","first-page":"289","article-title":"Plague around the world in 2019","volume":"94","author":"E Bertherat","year":"2019","journal-title":"Wkly Epidemiol Rec"},{"key":"pntd.0014463.ref002","doi-asserted-by":"crossref","first-page":"61","DOI":"10.1146\/annurev-ento-120710-100717","article-title":"Transmission of flea-borne zoonotic agents","volume":"57","author":"RJ Eisen","year":"2012","journal-title":"Annu Rev Entomol"},{"key":"pntd.0014463.ref003","first-page":"1","article-title":"Yersinia pestis: The natural history of Plague","volume":"34","author":"R Barbieri","year":"2021","journal-title":"Clin Microbiol Rev"},{"key":"pntd.0014463.ref004","doi-asserted-by":"crossref","first-page":"215","DOI":"10.1146\/annurev-micro-090816-093521","article-title":"\u201cFleaing\u201d the Plague: Adaptations of Yersinia pestis to Its Insect Vector That Lead to Transmission","volume":"71","author":"BJ Hinnebusch","year":"2017","journal-title":"Annu Rev Microbiol"},{"issue":"6","key":"pntd.0014463.ref005","doi-asserted-by":"crossref","first-page":"1183","DOI":"10.1093\/jme\/tjv128","article-title":"The Role of Early-Phase Transmission in the Spread of Yersinia pestis","volume":"52","author":"RJ Eisen","year":"2015","journal-title":"J Med Entomol"},{"issue":"2","key":"pntd.0014463.ref006","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1051\/vetres:2008039","article-title":"Adaptive strategies of Yersinia pestis to persist during inter-epizootic and epizootic periods","volume":"40","author":"RJ Eisen","year":"2009","journal-title":"Vet Res"},{"issue":"5273","key":"pntd.0014463.ref007","doi-asserted-by":"crossref","first-page":"367","DOI":"10.1126\/science.273.5273.367","article-title":"Role of the Yersinia pestis hemin storage (hms) locus in the transmission of plague by fleas","volume":"273","author":"BJ Hinnebusch","year":"1996","journal-title":"Science"},{"issue":"4","key":"pntd.0014463.ref008","doi-asserted-by":"crossref","DOI":"10.1371\/journal.ppat.1008440","article-title":"A refined model of how Yersinia pestis produces a transmissible infection in its flea vector","volume":"16","author":"A Dewitte","year":"2020","journal-title":"PLoS Pathog"},{"key":"pntd.0014463.ref009","first-page":"423","article-title":"LXVII. 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