Undiagnosed Cases of Human Pneumonia Following Exposure to Chlamydia psittaci from an Infected Rosella Parrot

Abstract

This report describes two cases of occupational exposure to Chlamydia psittaci following dissection of an infected Rosella (Platycercus elegans). The C. psittaci infections (with one of them resulting in diagnosed pneumonia and hospitalisation) were undiagnosed during routine medical investigations but later established due to epidemiological and clinical evidence, and molecular testing of the archived Rosella’ specimens. This case report stresses the importance of correct application and interpretation of diagnostic tests and the need to raise awareness about this zoonotic pathogen among medical practitioners and people exposed to potential animal carriers. Our findings suggest other infected individuals might be misdiagnosed and that C. psittaci (psittacosis) is likely to be underreported in Australia. This case highlights the need to operationalise the One Health concept. We call for improved communication between human and animal health service providers to allow accurate and rapid diagnosis of this zoonotic disease and raised awareness among medical practitioners. Further targeted surveys of wild birds (and other animals) should be conducted to improve assessment of risks to the general population and people working with or exposed to wild birds.

One clone to rule them all: Culture-independent genomics of Chlamydia psittaci from equine and avian hosts in Australia

“…Our phylogenetic analyses: (i) reiterate the clonality and generalist host nature of the ST24 lineage; (ii) support lower genetic diversity and host association within the 'pigeon-type' PG4, where our pigeon strain RacingPigeon_24 clustered; and (iii) demonstrate that overall, the C. psittaci population is genetically diverse in agreement with previous studies [7,11,13,14,17]. Whilst we have now expanded Australian psittacine C. psittaci ST24 genomes from one (CR009) to six, provided the first pigeon C. psittaci from Australia and confirmed that the ST24 clonality of the equine reproductive loss strains, another limitation of our study was that we were not able to obtain additional samples containing previously genotyped contemporary diverse strains from other Australian non-psittacine, human, livestock and/or marsupials hosts [15,44,45].…”

“…psittaci ST24 genomes from one (CR009) to six, provided the first pigeon C. psittaci from Australia and confirmed that the ST24 clonality of the equine reproductive loss strains, another limitation of our study was that we were not able to obtain additional samples containing previously genotyped contemporary diverse strains from other Australian non-psittacine, human, livestock and/or marsupials hosts [15, 44, 45].…”

“…psittaci strains causing equine reproductive loss and the factors that increase the risk of infection spillover [5] but also to assess the genetic diversity of C. psittaci in the broader range of avian and non-avian hosts, including humans [14, 15, 44, 45, 58]. The opportunities for ongoing spillover due to habitat degradation/encroachment (or increase) of the wildlife/livestock interface and reduced food/water resources for birds driving them into paddocks to feed on horse food are plausible [59].…”

“…Molecular and/or cell biology/infection studies to dissect the significant pathogenicity of C. psittaci and to understand the risk posed by C. psittaci to livestock and humans are being increasingly conducted in Australia and worldwide [7,11,14,15,[55][56][57]. In Australia, further studies must focus on understanding the pathogenicity of C. psittaci strains causing equine reproductive loss and the factors that increase the risk of infection spillover [5] but also to assess the genetic diversity of C. psittaci in the broader range of avian and non-avian hosts, including humans [14,15,44,45,58]. The opportunities for ongoing spillover due to habitat degradation/encroachment (or increase) of the wildlife/livestock interface and reduced food/water resources for birds driving them into paddocks to feed on horse food are plausible [59].…”

Animal Chlamydiae: A Concern for Human and Veterinary Medicine

“…Complementing the study above and further highlighting the need to implement the One Health concept, the report by Chaber and team describes two cases of human psittacosis following exposure during the dissection of an infected Rosella parrot in Australia, which was infected with an ST24/ ompA genotype A C. psittaci strain [ 22 ]. One patient was hospitalized with pneumonia, and in both cases, the disease was not diagnosed during routine medical investigations.…”