Equine psittacosis: an emerging cause of equine abortion and neonatal illness in Australia
Charles El-Hage A B * , Joanne Devlin B , Kristopher Hughes C , Cheryl Jenkins D , Susan Anstey E , Martina Jelocnik F and James Gilkerson A BA
B
C
D
E
F
Dr Charlie El-Hage graduated from The University of Melbourne and worked locally and internationally in rural veterinary practices, Charlie returned to The University of Melbourne as an equine clinician and lecturer in 2001, subsequently completing a PhD in equine virology and immunology in 2016. Now an honorary fellow, he has maintained an active range of projects supervising students in equine interests including infectious diseases, welfare, immunology, toxicology and endocrinology. He has a range of publications include reviews and original articles. |
Prof. Joanne Devlin is head of the Melbourne Veterinary School, having graduated from The University of Sydney and completed her PhD in veterinary virology at The University of Melbourne. Her research includes diseases of domestic animals and wildlife, including birds, horses and marsupials including vaccine development and testing. She was awarded an Australian Research Council (ARC) Postdoctoral Fellowship in 2008. She is a current member of the ARC College of Experts. |
Kristopher Hughes is a Fellow of the Australian and New Zealand College of Veterinary Scientists in equine medicine and a diplomate of the European College of Equine Internal Medicine. Kris is currently professor of equine medicine at Charles Sturt University, Australia. Kris is active in referral equine veterinary practice, undergraduate and post-graduate teaching, research and veterinary hospital management. His research interests include infectious diseases of horses, equine parasitology, equine endocrinology and intensive care of horses. |
Cheryl Jenkins is a principal research scientist leading a molecular biology laboratory within the Microbiology and Parasitology section at the Elizabeth Macarthur Agricultural Institute. She has 15 years’ experience in molecular biology with a focus on microbial pathogenesis, diagnostic test development, proteomics and genomics. She has over 80 published works in peer-reviewed journals. |
Dr Susan Anstey is a distinguished veterinarian and researcher. She graduated from The University of Queensland in 1991, laying the foundation for a successful career in veterinary medicine. Since 2001, Dr Anstey has owned and operated Kenilworth Veterinary Surgery, a mixed animal practice. Dr Anstey completed her PhD at the University of the Sunshine Coast in 2023. Her doctoral research focused on the epidemiology of Chlamydia psittaci in pregnant thoroughbred mares, contributing valuable insights to equine reproductive health and disease prevention. |
Dr Martina Jelocnik is a lecturer in microbiology at the University of the Sunshine Coast. She leads the ‘Molecular Chlamydia’ research team that investigates key questions in the molecular epidemiology, zoonotic potential, control and diagnosis of veterinary chlamydia. Martina’s research is focused on fine-detailed molecular epidemiology of chlamydial infections in Australian livestock as well as wildlife, employing novel molecular approaches. Martina has been at the forefront of the emerging chlamydia infections in horses and applying innovative ‘One Health approach’ to dissect these infections. She also works on the development of rapid isothermal assays that can be deployed at the point-of-care for detection of chlamydia. |
Prof. James Gilkerson is an equine veterinarian whose research interests are focused on the diagnosis, epidemiology and prevention of infectious diseases. James graduated from The University of Sydney awarded a BVSc, BSc (Vet) and a PhD and is currently a professor of veterinary microbiology and director of the Centre for Equine Infectious Disease at The University of Melbourne. James has written more than 130 peer-reviewed publications, numerous textbook chapters and has supervised 20 PhD students to completion. |
Abstract
Chlamydia psittaci is an obligate, intracellular, bacterial pathogen generally associated with clinical and subclinical infection of birds. It is a zoonotic pathogen in humans causing psittacosis a serious respiratory disease and reported to cause infection in animals including cattle, sheep and horses. Although there have been sporadic reports of disease due to C. psittaci in horses since the last century, reports from Australia over the last decade have highlighted the potential of disease in horses and zoonotic transfer. Epizootics of abortions and stillbirths in mares and serious neonatal disease, termed equine psittacosis (EP), have highlighted the potential of C. psittaci to both cause disease in horses and recognise them as major mammalian vectors for zoonotic transmission. Molecular characterisation techniques for these Australian isolates have demonstrated that the majority of equine associated C. psittaci strains have identified the globally disseminated pathogenic 6BC/ST24 type. Diagnosis is primarily through molecular techniques to identify C. psittaci genomically as seroconversion has not been reliably observed in horses. In tissues from abortion samples histopathological changes typically include lymphohistiocytic placentitis though this is neither a sensitive or specific finding in cases of EP. Neonatal foal illness is characterised by severe interstitial pneumonia and disease is generally fatal. Recognition of EP has heightened both awareness of C. psittaci as an equine abortigenic pathogen and the zoonotic threat that infected horses pose. Personal protective equipment should be donned by exposed personnel and strict biosecurity and control measures should be enforced following equine abortion or foetal loss cases and neonatal illness pending diagnostic evaluation.
Keywords: Chlamydia psittaci, equine psittacosis, mare abortion, neonatal illness, placentitis, psittacines.
Dr Charlie El-Hage graduated from The University of Melbourne and worked locally and internationally in rural veterinary practices, Charlie returned to The University of Melbourne as an equine clinician and lecturer in 2001, subsequently completing a PhD in equine virology and immunology in 2016. Now an honorary fellow, he has maintained an active range of projects supervising students in equine interests including infectious diseases, welfare, immunology, toxicology and endocrinology. He has a range of publications include reviews and original articles. |
Prof. Joanne Devlin is head of the Melbourne Veterinary School, having graduated from The University of Sydney and completed her PhD in veterinary virology at The University of Melbourne. Her research includes diseases of domestic animals and wildlife, including birds, horses and marsupials including vaccine development and testing. She was awarded an Australian Research Council (ARC) Postdoctoral Fellowship in 2008. She is a current member of the ARC College of Experts. |
Kristopher Hughes is a Fellow of the Australian and New Zealand College of Veterinary Scientists in equine medicine and a diplomate of the European College of Equine Internal Medicine. Kris is currently professor of equine medicine at Charles Sturt University, Australia. Kris is active in referral equine veterinary practice, undergraduate and post-graduate teaching, research and veterinary hospital management. His research interests include infectious diseases of horses, equine parasitology, equine endocrinology and intensive care of horses. |
Cheryl Jenkins is a principal research scientist leading a molecular biology laboratory within the Microbiology and Parasitology section at the Elizabeth Macarthur Agricultural Institute. She has 15 years’ experience in molecular biology with a focus on microbial pathogenesis, diagnostic test development, proteomics and genomics. She has over 80 published works in peer-reviewed journals. |
Dr Susan Anstey is a distinguished veterinarian and researcher. She graduated from The University of Queensland in 1991, laying the foundation for a successful career in veterinary medicine. Since 2001, Dr Anstey has owned and operated Kenilworth Veterinary Surgery, a mixed animal practice. Dr Anstey completed her PhD at the University of the Sunshine Coast in 2023. Her doctoral research focused on the epidemiology of Chlamydia psittaci in pregnant thoroughbred mares, contributing valuable insights to equine reproductive health and disease prevention. |
Dr Martina Jelocnik is a lecturer in microbiology at the University of the Sunshine Coast. She leads the ‘Molecular Chlamydia’ research team that investigates key questions in the molecular epidemiology, zoonotic potential, control and diagnosis of veterinary chlamydia. Martina’s research is focused on fine-detailed molecular epidemiology of chlamydial infections in Australian livestock as well as wildlife, employing novel molecular approaches. Martina has been at the forefront of the emerging chlamydia infections in horses and applying innovative ‘One Health approach’ to dissect these infections. She also works on the development of rapid isothermal assays that can be deployed at the point-of-care for detection of chlamydia. |
Prof. James Gilkerson is an equine veterinarian whose research interests are focused on the diagnosis, epidemiology and prevention of infectious diseases. James graduated from The University of Sydney awarded a BVSc, BSc (Vet) and a PhD and is currently a professor of veterinary microbiology and director of the Centre for Equine Infectious Disease at The University of Melbourne. James has written more than 130 peer-reviewed publications, numerous textbook chapters and has supervised 20 PhD students to completion. |
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