Globetrotting strangles: the unbridled national and international transmission of Streptococcus equi between horses

Catriona Mitchell, Karen F Steward, Amelia R L Charbonneau, Saoirse Walsh, Hayley Wilson, John F Timoney, Ulli Wernery, Marina Joseph, David Craig, Kees van Maanen, Annelies Hoogkamer-van Gennep, Albertine Leon, Lucjan Witkowski, Magdalena Rzewuska, Ilona Stefańska, Monika Żychska, Gunther van Loon, Ray Cursons, Olivia Patty, Els AckeJames R Gilkerson, Charles El-Hage, Joanne Allen, Hiroshi Bannai, Yuta Kinoshita, Hidekazu Niwa, Teótimo Becú, John Pringle, Bengt Guss, Reinhard Böse, Yvonne Abbott, Lisa Katz, Bernadette Leggett, Tom C Buckley, Shlomo E Blum, Fátima Cruz López, Ana Fernández Ros, Maria Cristina Marotti Campi, Silvia Preziuso, Carl Robinson, J Richard Newton, Ellen Schofield, Ben Brooke, Mike Boursnell, Nicolas de Brauwere, Roxane Kirton, Charlotte K Barton, Khalil Abudahab, Ben Taylor, Corin A Yeats, Richard Goater, David M Aanensen, Simon R Harris, Julian Parkhill, Matthew T G Holden, Andrew S Waller*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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The equine disease strangles, which is characterized by the formation of abscesses in the lymph nodes of the head and neck, is one of the most frequently diagnosed infectious diseases of horses around the world. The causal agent, Streptococcus equi subspecies equi, establishes a persistent infection in approximately 10 % of animals that recover from the acute disease. Such 'carrier' animals appear healthy and are rarely identified during routine veterinary examinations pre-purchase or transit, but can transmit S. equi to naïve animals initiating new episodes of disease. Here, we report the analysis and visualization of phylogenomic and epidemiological data for 670 isolates of recovered from 19 different countries using a new core-genome multilocus sequence typing (cgMLST) web bioresource. Genetic relationships among all 670 S. equi isolates were determined at high resolution, revealing national and international transmission events that drive this endemic disease in horse populations throughout the world. Our data argue for the recognition of the international importance of strangles by the Office International des Épizooties to highlight the health, welfare and economic cost of this disease. The Pathogenwatch cgMLST web bioresource described herein is available for tailored genomic analysis of populations of S. equi and its close relative subspecies that are recovered from horses and other animals, including humans, throughout the world. This article contains data hosted by Microreact.
Original languageEnglish
Article number000528
Number of pages14
JournalMicrobial Genomics
Issue number3
Early online date8 Mar 2021
Publication statusPublished - 8 Mar 2021


  • Streptococcus equi
  • Genome diversity
  • Pandemic
  • Strangles
  • Transmission


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