Clinical and microbiological features of Chlamydia Psittaci infection in Australia

Abstract

In 2002 a large outbreak of psittacosis occurred in the upper Blue Mountains region of New South Wales. Over the next seven years I undertook clinical surveillance and case finding in this region. With improved diagnosis, it was possible to identify cases earlier and collect a range of material including upper respiratory tract specimens in order to culture the organism. Human isolates were obtained and whole genome sequencing performed in order to determine the phylogenetic relationship with other known strains as well as an avian specimen from this area. Diagnosis was improved using molecular methods as well as serology and culture. These were applied in a cluster of cases at a veterinary practice with quantitation used to help explain infectivity. Over a seven year period, cases from this area were detected to be occurring on a regular basis. Clinical details from all cases were documented and review with comparison to other large clinical series. Cases occurred in a seasonal fashion each year and had clinical features consistent with the previous case series. This work was the first to suggest that psittacosis may be endemic in this region. Whole genome sequencing of human and avian isolates from this area showed little variation between strains and very close similarity with the 1930s outbreak strain known as 6BC. This surprising finding led me to speculate as to an Australian origin of the outbreak of 1930. The same strain was also detected from an equine human outbreak in NSW in 2014. Publications associated with this thesis are listed on page 4.