Suspected chlamydial foetal loss highlights the need for standardised on-farm protocols.
Abstract: Chlamydia psittaci is a recognised cause of late-term equine foetal loss and poses a zoonotic risk in Australia. However, a management strategy is lacking to protect at-risk humans handling infected aborted material and pregnant mares. This study proposes a protocol for approaching C. psittaci foetal loss after investigating four foetal losses that occurred on a horse stud in the Hunter Valley, Australia in 2021. Swabs from the foetal loss cases (n = 4), close contact mares (n = 59), and foals of the close contact mares (n = 33) were collected and tested for C. psittaci using both isothermal points of care and quantitative polymerase chain reaction (qPCR) laboratory-based testing. Genotyping was performed utilising C. psittaci multilocus sequence typing and ompA sequencing from C. psittaci positive pooled foetal and placental (n = 3) DNA. Foetal and placental samples from the four foetal loss cases were all positive for C. psittaci with 100% agreement between the isothermal swab testing on the farm and qPCR DNA testing at an external laboratory. Genotyping revealed the clonal and identical sequence type 24 (ST24) C. psittaci strains in all samples. C. psittaci was not detected in close contact with mares or their foals. There was no statistically significant difference in foal survival between the close contact mare groups that did and did not receive antimicrobial intervention (P > 0.05). The proposed protocol is intended to raise awareness and begin a discussion for guidelines around handling of chlamydial foetal loss cases in late pregnant mares which pose a zoonotic threat to farm workers and veterinarians.
© 2022 The Authors. Australian Veterinary Journal published by John Wiley & Sons Australia, Ltd on behalf of Australian Veterinary Association.
Publication Date: 2022-09-07 PubMed ID: 36071558PubMed Central: PMC10087770DOI: 10.1111/avj.13206Google Scholar: Lookup
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- Journal Article
Summary
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This research paper reports on an investigation into foetal losses in horses due to Chlamydia psittaci, a pathogen which also poses a risk to humans. The study advocates for official protocols in handling such cases to protect both equine and human health.
Background
- Chlamydia psittaci is a bacterium known to cause late-term abortions in horses and is considered a zoonotic risk, meaning it can be transmitted from animals to humans.
- In Australia, however, there hasn’t been a clear management strategy to protect humans — particularly those who handle aborted materials or deal with pregnant mares — from any possible infection with the bacteria.
Purpose and Methods of the Research
- Four cases of foetal loss on a horse farm in Hunter Valley, Australia in 2021 prompted the researchers to conduct this study and propose a protocol for dealing with such cases.
- The team collected swabs from four mares that had experienced foetal loss, as well as from 59 other mares in close contact with the affected mares, and 33 foals of these close contact mares. All samples were tested for C. psittaci using two methods: isothermal points of care (a type of rapid diagnostic test) and quantitative polymerase chain reaction or qPCR (a lab-based test).
- In addition, the team performed genotyping on the DNA of pooled foetal and placental samples to uncover the specific type of C. psittaci strain present.
Findings
- All four mares that had experienced foetal losses tested positive for C. psittaci.
- The discrepancies between the isothermal testing done on the farm and the lab-based qPCR test results were consistent.
- Genotyping revealed that all samples tested positive for the same strain of the pathogen, sequence type 24 (ST24).
- The bacteria was not detected in any of the mares or foals that were in close contact with the infected mares.
- No significant difference in foal survival rates was observed between the groups of mares that did and didn’t receive antimicrobial drugs.
Implications of the Study
- This research underscores the dire need for standardised guidelines and protocols for handling cases of chlamydial foetal loss in horses, in order to safeguard farm workers and veterinarians from potential zoonotic transmission.
Cite This Article
APA
Anstey SI, Jenkins C, Jelocnik M.
(2022).
Suspected chlamydial foetal loss highlights the need for standardised on-farm protocols.
Aust Vet J, 100(12), 600-604.
https://doi.org/10.1111/avj.13206 Publication
Researcher Affiliations
- Centre for Bioinnovation, University of the Sunshine Coast, Sippy Downs, Queensland, Australia.
- NSW Department of Primary Industries, Animal and Plant Health laboratories, Elizabeth Macarthur Agricultural Institute, Menangle, New South Wales, Australia.
- Centre for Bioinnovation, University of the Sunshine Coast, Sippy Downs, Queensland, Australia.
MeSH Terms
- Horses
- Animals
- Female
- Pregnancy
- Humans
- Farms
- Horse Diseases / diagnosis
- Placenta
- Psittacosis / veterinary
- Chlamydophila psittaci / genetics
- Chlamydia
Grant Funding
- Agrifutures Australia
- Centre for Bioinnovation, University of the Sunshine Coast
Conflict of Interest Statement
None of the authors of this paper has a financial or personal relationship with other people or organisations that could inappropriately influence or bias the content of the paper.
References
This article includes 11 references
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Citations
This article has been cited 1 times.- El-Hage C, Legione A, Devlin J, Hughes K, Jenkins C, Gilkerson J. Equine Psittacosis and the Emergence of Chlamydia psittaci as an Equine Abortigenic Pathogen in Southeastern Australia: A Retrospective Data Analysis. Animals (Basel) 2023 Jul 28;13(15).
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