Epidemiology of Chlamydia psittaci infections in pregnant Thoroughbred mares and foals.
Abstract: Late-term foal loss due to the traditional avian pathogen Chlamydia psittaci recently emerged as a threat to the Australian Thoroughbred industry. A longitudinal study of 14 stud farms was undertaken to better understand C. psittaci infection in pregnant mares and their foals by evaluating C. psittaci prevalence, equine herpesvirus-1 (EHV-1) co-infection, avian reservoirs, and potential risk factors. Mucosal swabs taken from 228 healthy pregnant mares and their foals were tested for C. psittaci and EHV-1 using species-specific qPCR assays. No foal loss was recorded due to either pathogen, and no mare tested positive to either C. psittaci or EHV-1. However, healthy newborn foals tested positive to both pathogens, at low levels, with 13.2% (n = 30/228) and 14.5% (n = 33/228) prevalence for C. psittaci and EHV-1, respectively. Co-infection occurred in 1.3% (n = 3/228) of foals. In avian environmental faecal samples collected from the same studs, C. psittaci was detected at 5.3% (n = 5/94). Multiple logistic regression modelling found that foals born in winter were more likely to be infected with C. psittaci (adjusted odds ratio = 15.83; P < 0.001; Confidence Interval 5.12-48.49). Being a maiden mare, absence of prophylactic vaginal suture, interventions in the last trimester and residing on a farm with prior history of C. psittaci abortion posed no higher risk to infection in the newborn. Analysis of all reported C. psittaci abortion cases (Hunter Valley, 2016-2019) revealed a dominant C. psittaci sequence type (denoted ST24) and a significant correlation with frost events (Spearmans' rho = 0.44; P = 0.002).
Crown Copyright © 2021. Published by Elsevier Ltd. All rights reserved.
Publication Date: 2021-04-26 PubMed ID: 34148605DOI: 10.1016/j.tvjl.2021.105683Google Scholar: Lookup
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Summary
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The research article discusses a study on the prevalence and impact of Chlamydia psittaci infections in pregnant Thoroughbred mares and their foals, including potential risk factors and occurrence during different seasons.
Study Methodology
- The study was conducted across 14 stud farms to assess the nature of C. psittaci infection in pregnant horses and their offspring.
- A total of 228 healthy pregnant mares and their foals contributed mucosal swabs for assessment.
- The researchers also evaluated for equine herpesvirus-1 (EHV-1) co-infection, possible avian reservoirs, and risk factors with the potential to contribute to infection prevalence.
- The researchers used species-specific qPCR assays to check for the presence of both C. psittaci and EHV-1.
- They also collected and tested avian environmental fecal samples from the same locations.
Findings of the Study
- No foal loss due to either C. psittaci or EHV-1 was noted.
- All tested mares showed negative for both pathogens.
- Nevertheless, some healthy newborn foals tested positive for low levels of both pathogens: 13.2% for C. psittaci and 14.5% for EHV-1.
- Only 1.3% of the tested foals showed co-infection.
- The occurrence of C. psittaci in environmental avian fecal matter was found to be 5.3%.
- A significantly elevated adjusted odds-ratio of 15.83 was found for C. psittaci infection in foals born in winter.
- Becoming a maiden mare, lack of preventive vaginal suture, interventions in the last trimester, and staying on a farm with a past C. psittaci abortion history were not found to pose a heightened infection risk in newborn foals.
Additional Observations
- Upon analyzing reported C. psittaci abortion cases from 2016 to 2019 in the Hunter Valley area, a dominant sequence type (ST24) was noted.
- There was a notable correlation between occurrence of the disease and frost events.
Conclusions
- The study highlights the prevalence of C. psittaci and EHV-1 in newborn foals, despite the absence of these pathogens in healthy, pregnant mares.
- Winter birth appears to be a significant risk factor for C. psittaci infection.
- Further research is needed to understand the full scope of C. psittaci prevalence, its potential vectors, and possible preventive measures.
Cite This Article
APA
Anstey S, Lizárraga D, Nyari S, Chalmers G, Carrick J, Chicken C, Jenkins C, Perkins N, Timms P, Jelocnik M.
(2021).
Epidemiology of Chlamydia psittaci infections in pregnant Thoroughbred mares and foals.
Vet J, 273, 105683.
https://doi.org/10.1016/j.tvjl.2021.105683 Publication
Researcher Affiliations
- Genecology Research Centre, University of the Sunshine Coast, Sippy Downs, Qld, 4557, Australia.
- Genecology Research Centre, University of the Sunshine Coast, Sippy Downs, Qld, 4557, Australia; The School of Natural Sciences, University of Tasmania, 7000, Australia.
- Genecology Research Centre, University of the Sunshine Coast, Sippy Downs, Qld, 4557, Australia.
- The School of Science, Technology and Engineering, University of the Sunshine Coast, Sippy Downs, Qld, 4557, Australia.
- Equine Specialist Consulting, Scone, NSW, 2337, Australia.
- Scone Equine Hospital, Scone, NSW, 2337, Australia.
- NSW Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Menangle, NSW, 2568, Australia.
- The University of Queensland, School of Veterinary Science, Gatton, Qld, 4343, Australia.
- Genecology Research Centre, University of the Sunshine Coast, Sippy Downs, Qld, 4557, Australia.
- Genecology Research Centre, University of the Sunshine Coast, Sippy Downs, Qld, 4557, Australia. Electronic address: mjelocni@usc.edu.au.
MeSH Terms
- Abortion, Veterinary / epidemiology
- Abortion, Veterinary / microbiology
- Animals
- Animals, Newborn / microbiology
- Australia / epidemiology
- Birds
- Chlamydophila psittaci / isolation & purification
- Feces / microbiology
- Female
- Herpesviridae Infections / veterinary
- Herpesvirus 1, Equid / isolation & purification
- Horse Diseases / epidemiology
- Horse Diseases / microbiology
- Horses
- Male
- Pregnancy
- Psittacosis / epidemiology
- Psittacosis / veterinary
- Seasons
Citations
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