Repeated nasopharyngeal lavage predicts freedom from silent carriage of Streptococcus equi after a strangles outbreak.
Abstract: The value of repeated nasopharyngeal lavage (NPL) to detect silent carriers of Streptococcus equi has not been investigated. Objective: Determine if results of serial testing for S. equi by NPL predicts subsequent true carrier status as determined by both NPL and guttural pouch lavage. Methods: An outbreak of strangles with 100% morbidity in 41 mature Icelandic horses was followed prospectively to investigate development of silent carriers. All were initially positive to S. equi on NPL. The farm was closed to horse movement during the entire study. Methods: Prospective observational study. Testing for S. equi was performed by NPL at weeks 18, 28, 29, and 30 postindex case and subsequently at week 45 by both NPL and guttural pouch lavage. Carrier status at week 45 was compared to results obtained at weeks 18, 28, 29, and 30. Descriptive statistics were calculated. Comparisons were made using Fisher's exact test or the Freeman-Halton extension with a P < .05 level of significance. Results: Of 24 noncarriers at week 45, only 4 horses were negative on all 3 consecutive weekly NPL samples at weeks 28 to 30. However, 10 of the 11 horses with at least 3 negative NPL obtained from weeks 18, 28, 29, and 30 were S. equi-free at week 45 (P = .03). Conclusions: Repeated NPL on at least 3 separate occasions can assist in predicting S. equi carrier-free status in horses after recovery from a strangles outbreak.
© 2022 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.
Publication Date: 2022-01-24 PubMed ID: 35072293PubMed Central: PMC8965236DOI: 10.1111/jvim.16368Google Scholar: Lookup
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- Journal Article
- Observational Study
- Veterinary
Summary
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The study investigates the effectiveness of repeated nasopharyngeal lavage (NPL) in detecting silent carriers of Streptococcus equi (S. equi) among horses, concluding that multiple NPLs could effectively predict S. equi-free horses after a strangles outbreak.
Study Objective and Methodology
- The study aimed to evaluate if the results of serial testing for S. equi using NPL could predict true carrier status as confirmed by NPL and guttural pouch lavage.
- A strangles outbreak involving 41 mature Icelandic horses was monitored. All horses initially tested positive to S. equi on NPL testing.
- During the entire examination, horse movement on the farm was restricted.
- This was a prospective observational study where testing for S. equi was performed by NPL at weeks 18, 28, 29, 30, and 45 postindex case. The last test also involved guttural pouch lavage.
- Descriptive statistics were computed and comparisons were made using certain statistical tests at a significance level of P < .05.
Results and Conclusion
- By week 45, 24 horses were identified as noncarriers. Out of them, only 4 horses had three consecutive weekly negative NPL samples at weeks 28 to 30.
- However, out of 11 horses that had at least 3 negative NPL results from weeks 18, 28, 29, and 30, 10 were S. equi-free at week 45.
- These results suggest that repeated NPL testing on at least three separate occasions can help predict whether a horse will be a S. equi carrier after recovery from a strangles outbreak.
- This contributes vital insights for effectively managing strangles outbreaks and preventing further spread of the infection by early identification and isolation of carrier horses.
Cite This Article
APA
Pringle J, Aspán A, Riihimäki M.
(2022).
Repeated nasopharyngeal lavage predicts freedom from silent carriage of Streptococcus equi after a strangles outbreak.
J Vet Intern Med, 36(2), 787-791.
https://doi.org/10.1111/jvim.16368 Publication
Researcher Affiliations
- Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Uppsala, Sweden.
- The National Veterinary Institute, Uppsala, Sweden.
- Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, Uppsala, Sweden.
MeSH Terms
- Animals
- Carrier State / veterinary
- Disease Outbreaks / veterinary
- Freedom
- Horse Diseases / diagnosis
- Horse Diseases / epidemiology
- Horses
- Streptococcal Infections / diagnosis
- Streptococcal Infections / epidemiology
- Streptococcal Infections / veterinary
- Streptococcus equi
- Therapeutic Irrigation / veterinary
Grant Funding
- 221-2013-606 / Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning, Formas
Conflict of Interest Statement
Authors declare no conflict of interest.
References
This article includes 18 references
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Citations
This article has been cited 2 times.- McLinden LA, Kemp-Symonds JG, Daly JM, Blanchard AM, Waller AS, Freeman SL. Effectiveness of a screening protocol employed at a UK rescue centre to prevent introduction of strangles. Equine Vet J 2026 Mar;58(2):466-475.
- Weese JS, Saab M, Moore A, Cai H, McClure JT. Relationship between quantitative real-time PCR cycle threshold and culture for detection of Streptococcus equi subspecies equi. Can Vet J 2023 Jun;64(6):549-552.
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