Sporadic cases: Routine. Action should be carried out as part of routine duties. Data entry should be completed within 5 working days.
Cluster / Outbreak: High. Act as soon as possible, generally within one working day. Data entry should be completed within 3 working days.
Case management: Appropriate antibiotics under direction of the treating doctor. Determine likely source of infection.
Contact management: Ask about unwell co-exposed co-workers, family, and friends to help identify cases that may be associated with an outbreak.
Chlamydia psittaci1-2 (previously known as Chlamydophila psittaci ) a gram negative obligate intracellular bacterium. C psittaci is divided into eight serovars according to variation in the major outer membrane protein; serovar A to F, WC and M56. Subsequently, eight corresponding genotypes based on the sequencing of variable domains of the outer membrane protein A (ompA) gene were defined, with the later addition of genotype E/B. Each serovar/genotype is associated to a varying degree with a particular animal host; A to F with avian hosts, WC and M56 with mammalian hosts. Human infection has been associated with all avian host serovars.3
Birds are the major zoonotic reservoir of C. psittaci which has been documented in 467 species in 30 bird orders worldwide.4 In practice, most human infections are associated with pet or wild psittacine birds (such as lorikeets, budgerigars, cockatiels and cockatoos) and farmed birds such as poultry.3
[C. psittaci infections
in other mammalian species have been less well-studied with prevalence rates
potentially underestimated. C. psittaci
has been detected in dogs, cats, pigs, cattle, buffalo, goats, sheep and horses5-9 in association with
respiratory, intestinal and arthritic diseases, as well as reproductive loss.
The strongest evidence for the potential of C.
psittaci to cause infection and disease in a non-human mammalian host has
recently emerged in horses.10 The
results of this work revealed that C.
psittaci infection was present in tissues associated with equine
reproductive loss at a relatively high (20%) prevalence.11 In 2017 symptomatic foals were diagnosed with
C.psittaci in southern NSW.]
The disease in birds is referred to as avian chlamydiosis (AC). C. psittaci is excreted in the faeces and nasal discharges of infected birds. The organism can remain infectious for months if protected by organic debris such as cage litter or faeces. Infected birds, including asymptomatic birds may shed the bacteria intermittently for several months. Bacterial shedding can be exacerbated by stressors such as transportation, overcrowding and reproductive activities. Birds do not develop protective immunity and so may become reinfected.12
Humans usually become infected after inhaling C. psittaci which has been aerosolised from dried faeces, feather dust, or respiratory secretions (e.g. sneezed droplets) of infected birds, including birds which are asymptomatic carriers. Other means of exposure include mouth-to-beak contact and possibly the handling of plumage and tissues of infected birds. Even brief exposures can lead to symptomatic infection.12,13
Person-to-person transmission is rare, but has been reported, and includes instances of potential nosocomial transmission.14-17
the zoonotic risks of avian chlamydiosis are well documented, much less is
known about the zoonotic potential of C. psittaci in non-avian hosts. Transmission of C.
psittaci (and other closely related chlamydial organisms) to humans from
non-avian sources is likely under-recognised, but has been documented in case
studies of pregnant women exposed to abortion products from sheep (C.
abortus, formerly C. psittaci serotype 1), slaughterhouse workers,
cattle or sheep ranchers, and laboratory staff.18-21 There is also evidence
from case reports of human infection following exposure to infected foals.10]
Onset of illness follows an incubation period of 5-21 days,3 typically 10 days, but may be up to 4 weeks.5 Immunity following infection is incomplete and transitory, so patients can be reinfected.
Person-to-person transmission has been reported only rarely; hence the infectious period is unknown.
Psittacosis can result in a range of clinical manifestations from asymptomatic infection through mild flu-like illness to systemic illness with severe atypical pneumonia. Persons with symptomatic infection typically have abrupt onset of headache, fever, chills, malaise, and myalgia. They also usually develop a non-productive cough that can be accompanied by breathing difficulty and chest tightness.3,11 A pulse-temperature dissociation (fever without elevated pulse), enlarged spleen, and rash are sometimes observed and are suggestive of psittacosis in-patients with community-acquired pneumonia.
C. psittaci can affect other organ systems and result in endocarditis, myocarditis, hepatitis, arthritis, keratoconjunctivitis, and encephalitis. Severe illness is rare in pregnant women, but can result in respiratory failure, thrombocytopenia, hepatitis, and foetal death.3
Persons at higher risk include bird owners, pet shop employees, and persons whose occupation places them at risk for exposure (e.g. employees in poultry slaughtering and processing plants, veterinarians, veterinary technicians, laboratory workers, taxidermists, workers in avian quarantine stations, farmers, wildlife rehabilitators, and zoo workers).12 Lawn mowing without a grass catcher and gardening have also been associated with disease transmission.6 [Limited
evidence has suggested people who come into close contact with aborted material
from horses, or unwell foals, may also be at risk.10]
Any age group can be affected, although children rarely present with clinically significant illness3. Immunocompromised people do not appear to be at increased risk of contracting the disease.12
Between 2001 and 2014 there were 1687 notifications of psittacosis reported in Australia, with an average rate of 0.5 cases per 100,000 population. Rates peaked in 2003 and 2004 at 1.1 cases per 100,000 population for both years and were lowest in 2013 and 2014 at 0.1 cases per 100,000 population.13 Rates in NSW and Victoria are generally higher than other states. Males are more commonly affected than females, which may represent higher occupational exposure or testing bias. Notifications are highest in people aged 40 years or older. This may reflect more severe disease in older age groups rather than a difference in incidence.
Psittacosis is endemic in some areas of Australia8, and outbreaks have been reported. 6,9,22 Cases may report only indirect contact with birds (i.e. seeing birds and their excreta in the local environment).3,6,22
There is no vaccine available to protect against psittacosis. Prevention activities are focused largely on education of high risk groups such as staff of pet shops and poultry processing plants, as well as bird owners and/or breeders, trappers, veterinarians, zoo workers and taxidermists.
Pet shops and bird suppliers should contact [the NSW Department of Primary Industries (DPI)] for advice on quarantining new birds, management of infected birds, general hygiene and housing requirements for pet birds (see also Appendix 2: Avian chlamydiosis fact sheet for bird carers and suppliers).
The psittacosis fact sheet provides advice to the public about reducing the risk of household exposure to infected pet birds (see Appendix 1: Psittacosis (Ornithosis) fact sheet).
This advice includes:
Within 5 working days of notification enter confirmed and probable cases onto NCIMS. In the event of a re-infection, enter as a new case, as above.
[Public health units should liaise with the Communicable Diseases Branch (CDB)] about human cases to facilitate investigation of possible pet shop, wild bird, poultry or other bird sources. [CDB will request support through DPI for an inspection (see section 11. special situations).]
Suspected clusters or outbreaks (2 or more cases epidemiologically linked) in humans, linked to pet shops or bird breeders, should be reported to CDB with the patient’s age, sex, date of onset, laboratory status, possible sources of infection, other people thought to be at risk, and follow up action taken.
[NSW DPI] should report suspected clusters or outbreaks of avian chlamydiosis [to CDB] if there is associated human illness.
De-identified cases and suspected outbreaks associated with commercial poultry farms and processing plants should be reported to [NSW DPI].
During a recognised outbreak in an endemic area, CDB should provide advice to the public regarding protective practices.
Both conﬁrmed cases and probable cases should be notiﬁed.
A conﬁrmed case requires laboratory deﬁnitive evidence and clinical evidence.
A probable case requires laboratory suggestive evidence and clinical evidence and epidemiological evidence.
As with confirmed case.
Direct or indirect exposure to birds or bird products, or contact with a confirmed human or animal case.
A. C. psittaci MIF antibody is more specific than CF
antibody. However, positive serologic findings by both MIF and CF may occur as
a result of infection with other Chlamydia species and should be
interpreted with caution. This is most likely to occur with primary Chlamydia pneumoniae infection
from 5-15 years of age. Chlamydia spp. infection in those <5 years
of age may not produce a MIF or CF serological response.
B. MIF IgG antibody can persist for years whereas CF antibody
diminishes over months following Chlamydia spp. infection.
The most recent Australian national notifiable diseases case definition for psittacosis can be found at the Department of Health website
The clinical presentation of psittacosis can be similar to other respiratory pathogens and laboratory suggestive or confirmatory testing is required as part of the case definition.
NAT testing of respiratory specimens is the preferred diagnostic method.23Appropriate respiratory specimens include nasopharyngeal swabs, sputum specimens, and bronchoalveolar lavage specimens. C. psittaci is a biosafety risk group 3 organism and culture is not usually performed due to the inherent technical difficulties and biosafety concerns.
If culture is attempted, this should be performed in an appropriate physical containment level 3 (PC3) facility.24
Appropriate antibiotic treatment can delay or diminish the antibody response so a third serum specimen up to 8 weeks after the initial may be required to confirm diagnosis.
Within 3 working days of laboratory notification determine whether case is probable or confirmed and begin follow-up investigation. Notify CDB when an outbreak is identified.
The response to a notification will normally be carried out in collaboration with the case’s health carers. Regardless of who does the follow-up, for confirmed cases, PHU staff should ensure that action has been taken to:
A history of exposure to birds, bird products or excreta from 4 days up to 4 weeks before onset of symptoms should be sought.
Pay particular attention to pet bird contact/ownership, occupations that would bring the case into contact with birds, or recreational activities including gardening that would result in these exposures. Ask about unwell co-exposed co-workers, family, and friends to help identify cases that may be associated with a common exposure or an outbreak.
[Where appropriate ask about exposure to sick foals
or contact with aborted material from horses.]
This is the responsibility of the treating doctor. For the current recommended treatment, refer to the Therapeutic Guidelines.25
The case or relevant care-giver should be informed about nature of infection and mode of transmission. The psittacosis and avian chlamydiosis fact sheet should be provided, where relevant.
Standard infection control procedures are sufficient.
Refer to section 11. Special situations.
Birds that are suspected sources of human infection should be referred to a veterinarian for evaluation, testing and treatment by the owner. All birds with confirmed or probable avian chlamydiosis should be evaluated and managed by a veterinarian. To prevent reinfection, contaminated aviaries should be thoroughly cleaned and sanitised using routine protective measures (see section 11. Special situations). If the source of infection is a pet bird, obtain the history of ownership, date and place of acquisition, and bird's health history.
Sampling environmental surfaces in any setting is rarely warranted for single cases. Further advice can be obtained through [NSW DPI], which can assist in identifying local avian veterinary expertise.
[If other animals are suspected to be the source of a human infection
the PHU should notify CDB. A discussion concerning next steps may occur with NSW DPI and other experts from the appropriate field.]
Ask about unwell co-exposed co-workers, family, and friends to help identify cases that may be associated with an outbreak.
Where a bird with probable or confirmed avian chlamydiosis (AC) linked to a human case has been acquired from a pet store, dealer or breeder within 60 days of the onset of signs of illness, an investigation should be undertaken to ensure that there is no ongoing risk associated with the source of the bird.
Special control measures may be necessary at pet stores that have been linked to case or cases of human psittacosis, or where there has been a recognised avian outbreak. [A joint inspection between a PHU environmental health officer and NSW DPU should be conducted. The PHU should contact CDB who will liaise with NSW DPI to identify an appropriate NSW DPI officer. Contact CDB to request a pet store inspection] (see Appendix 3: Psittacosis Environmental Health Investigation Questionnaire).
Control measures typically include the isolation and management of sick birds. There is no public health or animal health requirement to destroy infected birds; however in many cases the owner may elect to euthanize the birds. Cleaning/disinfection of cages and other surfaces are required (see below). These measures should be undertaken on advice from and under supervision of a veterinarian. Where a pet store (include pet store bird suppliers) has been linked to human disease, the suppliers should be notified by telephone and by letter (see Appendix 6: Psittacosis: model letter to bird suppliers and pet shops). Also provide the Psittacosis (Ornithosis) Fact sheet and Avian chlamydiosis fact sheet for bird carers and suppliers.
Where infected birds are identified or suspected, the following guidelines should be followed by bird keepers:
and 2017, unexplained human respiratory illness clusters were associated with infected
horses in southern NSW. In 2014,
respiratory illness in five staff and students of a veterinary school was
linked to exposure to aborted material from a horse10, while in 2017,
illness in eleven staff and students of a veterinary school were investigated
and linked to exposure to infected foals which had required very close care.
If a cluster is suspected, the PHU should notify CDB. An expert group
will be formed to provide guidance on human and animal testing and control
Avian chlamydiosis is notifiable to the DPI in NSW.
Links to relevant legislation , including State and Territory Public Health Legislation, the Quarantine Act and the
National Health Security Act 2007.
Appendix 1: Psittacosis (Ornithosis) fact sheetAppendix 2: Avian chlamydiosis fact sheet for bird carers and suppliersAppendix 3: Psittacosis Environmental Health Investigation QuestionnaireAppendix 4: PHU Psittacosis Checklist Appendix 5: Psittacosis Disease Investigation FormAppendix 6: Psittacosis: model letter to bird suppliers and pet shops