{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,11]],"date-time":"2026-05-11T13:13:39Z","timestamp":1778505219957,"version":"3.51.4"},"reference-count":34,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,4,21]],"date-time":"2026-04-21T00:00:00Z","timestamp":1776729600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100010874","name":"Shandong Provincial Finance Department","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100010874","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Cell. Infect. Microbiol."],"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>This study integrated epidemiological investigation with whole-genome sequencing to elucidate the transmission chain and pathogen characteristics of a 2023 brucellosis outbreak in Shandong Province, providing evidence for targeted prevention and control.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Transmission chains were reconstructed through field epidemiological investigations, active case finding, and retrospective data review. Isolated strains were cultured and identified, followed by molecular tracing using multilocus variable-number tandem repeat analysis (MLVA) and core-genome single-nucleotide polymorphism (cgSNP) genotyping. Epidemiological and molecular data were integrated to assess transmission links.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      A total of 26 related cases were identified in this outbreak. Epidemiological investigation revealed that the outbreak originated from a flock of infected lambs introduced by an index case in 2022, with subsequent spread through local livestock trading networks affecting multiple villages. Ten\n                      <jats:italic>Brucella<\/jats:italic>\n                      strains were isolated, including nine of\n                      <jats:italic>Brucella melitensis<\/jats:italic>\n                      biovar 3 (\n                      <jats:italic>B. melitensis<\/jats:italic>\n                      bv. 3) and one of\n                      <jats:italic>B. melitensis<\/jats:italic>\n                      bv. 1. cgSNP analysis showed that the nine bv. 3 strains formed a single clonal cluster (0 SNP difference) and grouped with historical Shandong strains, indicating sustained local transmission. The bv. 1 strain represented a separate infection event, genetically distinct from the main outbreak cluster. Integrated analysis confirmed a complete molecular-epidemiological concordance for 38.5% (10\/26) of cases; the remaining 61.5% could not be definitively linked due to missing epidemiological data or lack of isolate recovery. Phylogenetic analysis further indicated co-circulation of multiple lineages in the region.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>This outbreak was primarily driven by the trade of locally infected sheep, facilitating regional spread. High-resolution molecular typing effectively complemented traditional epidemiology by uncovering concealed transmission chains and revealing the co-circulation of multiple lineages. These findings underscore the value of integrated molecular surveillance systems in key endemic regions to support human brucellosis control.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fcimb.2026.1794629","type":"journal-article","created":{"date-parts":[[2026,4,21]],"date-time":"2026-04-21T04:22:02Z","timestamp":1776745322000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Integrating epidemiology with genomic tracing to uncover concealed transmission networks in a brucellosis outbreak, Shandong, China"],"prefix":"10.3389","volume":"16","author":[{"given":"Chanjuan","family":"Huangfu","sequence":"first","affiliation":[{"name":"School of Public Health and Health Management, Shandong First Medical University","place":["Jinan, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Min","family":"Wang","sequence":"additional","affiliation":[{"name":"Clinical Laboratory, Children's Hospital Affiliated to Shandong University, Jinan Children's Hospital","place":["Jinan, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Junjie","family":"Fan","sequence":"additional","affiliation":[{"name":"Department of Infectious Disease Prevention and Control, Weifang Center for Disease Control and Prevention","place":["Weifang, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xiujun","family":"Ma","sequence":"additional","affiliation":[{"name":"Shandong Provincial Key Laboratory of Intelligent Monitoring, Early Warning, Prevention and Control for Infectious Diseases, Shandong Center for Disease Control and Prevention","place":["Jinan, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Haizong","family":"Zhang","sequence":"additional","affiliation":[{"name":"Department of Infectious Disease Prevention and Control, Linqu County Center for Disease Control and Prevention","place":["Weifang, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jing","family":"Yuan","sequence":"additional","affiliation":[{"name":"Department of Infectious Disease Prevention and Control, Linqu County Center for Disease Control and Prevention","place":["Weifang, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kuo","family":"Han","sequence":"additional","affiliation":[{"name":"Shandong Provincial Key Laboratory of Intelligent Monitoring, Early Warning, Prevention and Control for Infectious Diseases, Shandong Center for Disease Control and Prevention","place":["Jinan, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ti","family":"Liu","sequence":"additional","affiliation":[{"name":"Shandong Provincial Key Laboratory of Intelligent Monitoring, Early Warning, Prevention and Control for Infectious Diseases, Shandong Center for Disease Control and Prevention","place":["Jinan, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"ShuJun","family":"Ding","sequence":"additional","affiliation":[{"name":"Shandong Provincial Key Laboratory of Intelligent Monitoring, Early Warning, Prevention and Control for Infectious Diseases, Shandong Center for Disease Control and Prevention","place":["Jinan, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zengqiang","family":"Kou","sequence":"additional","affiliation":[{"name":"Shandong Provincial Key Laboratory of Intelligent Monitoring, Early Warning, Prevention and Control for Infectious Diseases, Shandong Center for Disease Control and Prevention","place":["Jinan, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yan","family":"Li","sequence":"additional","affiliation":[{"name":"Shandong Provincial Key Laboratory of Intelligent Monitoring, Early Warning, Prevention and Control for Infectious Diseases, Shandong Center for Disease Control and Prevention","place":["Jinan, China"]}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1965","published-online":{"date-parts":[[2026,4,21]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"1895","DOI":"10.3201\/eid1312.070527","article-title":"Changing epidemiology of human brucellosis, Germany 1962-2005","volume":"13","author":"Al Dahouk","year":"2007","journal-title":"Emerg. 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