Evidence map›Paper›PMID 40684376›Full record

ArticleEquine veterinary journal2026

Unwelcome neighbours: Tracking the transmission of Streptococcus equi in the United Kingdom horse population.

Abigail A McGlennon, Kristien L Verheyen, J Richard Newton, Andries van Tonder, Hayley Wilson, Julian Parkhill, Nicolas de Brauwere, Sara Frosth, Andrew S Waller

Abstract read
In one paragraph

Article in Equine veterinary journal, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 3 papers.

0numbers the graph read from it
0cells of the map it votes in
3citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

3 citing papers in PubMed.

  1. Article
  2. Article
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4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

9 authors.

Abigail A McGlennonRoyal Veterinary College, Hertfordshire, UK.ORCID https://orcid.org/0000-0002-3730-0184
Kristien L VerheyenRoyal Veterinary College, Hertfordshire, UK.ORCID https://orcid.org/0000-0002-5077-224X
J Richard NewtonDepartment of Veterinary Medicine, University of Cambridge, UK.ORCID https://orcid.org/0000-0002-6266-0616
Andries van TonderDepartment of Veterinary Medicine, University of Cambridge, UK.ORCID https://orcid.org/0000-0002-4380-5250
Hayley WilsonDepartment of Veterinary Medicine, University of Cambridge, UK.ORCID https://orcid.org/0000-0002-9914-2601
Julian ParkhillDepartment of Veterinary Medicine, University of Cambridge, UK.ORCID https://orcid.org/0000-0002-7069-5958
Nicolas de BrauwereRedwings Horse Sanctuary, Norwich, UK.
Sara FrosthDepartment of Animal Biosciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.ORCID https://orcid.org/0000-0002-4080-5183
Andrew S WallerIntervacc, Hägersten, Sweden.ORCID https://orcid.org/0000-0002-7111-9549

Funding

Horse Trust G2019
6 · The paper itself

Abstract

backgroundStrangles (Streptococcus equi infection) remains endemic in the UK, with ~300 laboratory diagnoses annually. Sub-clinically infected long-term carriers are considered a key driver of endemicity. Analysing genomes of circulating strains could provide valuable transmission insights of this pathogen.

objectivesTo determine the population structure and diversity of UK S. equi isolates and to model transmission using epidemiological and whole genome sequencing data. STUDY

designRetrospective cross-sectional epidemiological and genomic surveillance.

methodsA dated phylogenetic tree derived from 511 S. equi isolates collected from UK horses between 2015 and 2022 was reconstructed. Bayesian Analysis of Population Structure (BAPS) identified clusters of related genomes, while iGRAPH identified clusters of sequences appropriate for transmission analysis, performed using Transphylo.

resultsBAPS identified nine groups, with 82% of strains clustering into two (McG-BAPS3, McG-BAPS5). A statistically significant association (p < 0.001) was found between the year of recovery and trends in the frequency of McG-BAPS groups, with McG-BAPS3 increasing and McG-BAPS5 decreasing in prevalence over the study period. Eight transmission clusters encompassing 64% of total sequences (n = 286/447) underwent analysis. Sixteen direct transmission pairs were identified; 10 were between horses from different UK regions. A transmission chain extending over a 6-month period was inferred from isolates from nine horses. MAIN LIMITATIONS: Bacterial strains from sub-clinically infected carrier horses may be underrepresented due to data collection via positive laboratory diagnoses. Furthermore, a low sampling proportion relative to overall UK cases provided only a snapshot of broader, unsampled transmission events.

conclusionsThe rapid change in S. equi population structure indicates acutely infected/recently convalesced short-term carrier horses play a more influential role in transmission than long-term carriers. Our work provides novel insights to our understanding of S. equi transmission dynamics. Transmission of genetically related strains across diverse regions suggests a real-time sequence-based surveillance system could inform interventions to minimise transmission.

Indexed as

Horse DiseasesStreptococcal InfectionsStreptococcus equiAnimalsCross-Sectional StudiesHorsesPhylogenyRetrospective StudiesUnited Kingdombacteriologygenomicsinfectious diseaseSteptococcus equi

Identifiers

PMID40684376
PMCPMC12892377

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Registered trials

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.