Getting a grip on strangles: recent progress towards improved diagnostics and vaccines.
Authors: Waller Andrew S, Jolley Keith A
Journal: Veterinary journal (London, England : 1997)
Summary
Strangles remains one of the most prevalent and economically significant infectious diseases in equine populations worldwide, yet diagnostic and preventative strategies have historically lagged behind those for other equine pathogens. Waller and Jolley's 2007 review synthesises emerging evidence on the bacterium *Streptococcus equi*, focusing on how persistent carrier infections complicate disease transmission and control, alongside molecular advances that were beginning to reshape vaccine development at that time. The authors detail how SeM protein sequencing and allele characterisation via online databases could be leveraged for outbreak epidemiology, whilst highlighting the role of bacteriophage-mediated horizontal gene transfer in virulence evolution—a mechanism with significant implications for understanding strain variation and pathogenesis. For practitioners managing strangles cases, this work underscores the critical importance of identifying and managing subclinical carriers, whilst the molecular insights into phage-driven virulence acquisition pointed towards novel vaccine targets beyond conventional live or inactivated approaches. Although published over 15 years ago, the principles outlined—particularly regarding persistent infection's epidemiological significance and the molecular basis of S. equi strain diversity—remain foundational to current diagnostic interpretation and vaccine efficacy discussions.
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Practical Takeaways
- •Strangles diagnosis and management should incorporate understanding of persistent infections as a source of ongoing transmission on premises
- •New vaccine development based on SeM protein and virulence factor research offers improved preventative options for practitioners to recommend to horse owners
- •Molecular characterization tools are now available to track outbreak strains and understand epidemiological patterns of strangles on individual operations
Key Findings
- •Strangles remains one of the most commonly diagnosed and important infectious diseases of horses worldwide
- •SeM protein alleles can now be reassigned using sequence data from the N-terminal region and online database resources for outbreak epidemiological analysis
- •Phage-mediated acquisition of virulence factors plays a significant role in the molecular evolution of S. equi, suggesting new prophylactic intervention strategies
- •Persistent infections are significant in disease transmission and understanding pathogenesis is crucial for vaccine development