Oral Presentation MedVetPATHOGENS 2018

An epizootic of Chlamydia psittaci equine reproductive loss in Australia: Are the native parrots and other birds to blame? (#3)

Martina Jelocnik 1 , Cheryl Jenkins 2 , Brendon O'Rourke 2 , Catherine Chicken 3 , Joan Carrick 3 , Adam Polkinghorne 1
  1. Genecology Research Centre, University of the Sunshine Coast, Sippy Downs, Queensland, Australia
  2. Elizabeth Macarthur Agricultural Institute, NSW Department of Primary Industries, Menangle, NSW, Australia
  3. Scone Equine Hospital, Scone, New South Wales, Australia

Chlamydia psittaci is an avian pathogen capable of spill-over infections to humans. In Australia, cases of equine reproductive loss have recently come under the spotlight due to apparent zoonotic transmission of C. psittaci from equine placenta to humans, a previously unrecognised route of transmission for this organism.

We screened for C. psittaci in cases of equine reproductive loss, reported in New South Wales, Australia during the 2016-2017 foaling season. C. psittaci specific-PCR screening of foetal and placental tissue samples from cases of equine abortion (n=161) and foals with compromised health status (n=38) revealed C. psittaci positivity of 21.1% and 23.7%, respectively, detecting high chlamydial loads (> 1 × 106 organisms/mg of tissue) in samples. Genomic analysis and molecular typing of C. psittaci positive samples from this study and the previous Australian equine index case revealed that the equine strains from different studs in regional NSW were clonal, while the phylogenetic analysis revealed that the C. psittaci strains from both Australian equine disease clusters belong to the parrot-associated 6BC clade, again indicative of spill-over of C. psittaci infections from native Australian parrots (1,2).

Recently, we also described another case of C. psittaci-associated equine abortion in Southern Queensland region of Australia. Molecular typing revealed that the infecting equine strains were closely related to the C. psittaci strains typically associated with infections of pigeons globally (3).

The results of this work suggest that C. psittaci may be a more significant agent of equine reproductive loss than thought and that equine chlamydiosis may have resulted from spill-over of infected birds. A range of studies are now required to evaluate the exact role that C. psittaci plays in equine reproductive loss; the potential avian reservoirs and factors influencing infection spill-over; and the risk that these equine infections pose to human health.

  1. Jelocnik M, et al. An epizootic of Chlamydia psittaci equine reproductive loss associated with suspected spillover from native Australian parrots. Emerging Microbes and Infection 2018. 7(1):88 2. Jelocnik M, et al. Multi-locus sequence typing identifies an avian-like Chlamydia psittaci strain involved in equine placentitis and associated with subsequent human psittacosis. Emerging Microbes and Infection 2017. 6(2):e7. 3. Jelocnik M, et al. Molecular evidence to suggest pigeon-type Chlamydia psittaci in association with an equine foal loss. Transboundary and Emerging Diseases 2018. 65(3):911-915.