Community outbreak of psittacosis in a rural Australian town

doi:10.1016/S0140-6736(97)10444-5

The Lancet

Volume 351, Issue 9117, 6 June 1998, Pages 1697-1699

https://doi.org/10.1016/S0140-6736(97)10444-5 Get rights and content

Summary

Background

Health authorities in Victoria, Australia were notified of three men from a rural town with atypical pneumonia, admitted to hospital over 8 days. Initial serological testing suggested Chlamydia psittaci as the cause. We did a case-control study to find risk factors for psittacosis.

Methods

We searched for cases of pneumonia or severe flu-like illness through family physicians and the regional hospital. We selected three controls per case from the region's electoral roll. We collected blood for serological tests and administered questionnaires to all cases and controls.

Findings

We found 16 cases of psittacosis and one died. Most cases were clustered within a small geographical area, with a median age of 58 years (range 23–76), 15 (94%) of whom were male. Keeping, handling, or feeding domestic or wild birds was not associated with illness. Cases spent a median of 17·5 h per week in their garden, compared with a median of 5·2 h for controls (p=0·04) and were more likely to have mowed lawns during the 3 weeks before onset of illness than controls (odds ratio 4·81 [95% Cl 1·08–33·37]).

Interpretation

We showed that psittacosis outbreaks are not limited to direct contact with birds and pose new challenges for disease control. Modifications may be needed to work outdoors to decrease the risk of psittacosis.

Introduction

Psittacosis is a common disorder in birds caused by infection with Chlamydia psittaci. Infected birds may seem healthy, but can shed C psittaci in excreta and nasal secretions.1, 2 Transmission to human beings can occur when the agent is inhaled from bird secretions, desiccated droppings, or dust from feathers. The clinical presentation of psittacosis in human beings may include fever, malaise, headache, myalgia, and chills; cough is characteristically scant or dry and may be absent.³ Pneumonia, when present, is generally more extensive on radiography than would be expected from clinical signs. Several cases of atypical pneumonia possibly attributable to C psittaci were reported to the Department of Human Services, Victoria, Australia. We did a case-control study to find the risk factors for and extent of illness.

Section snippets

Methods

On Oct 16, 1995, the Department of Human Services was informed of three men with atypical pneumonia who had been transferred in the previous week from a rural hospital in the alpine town of Bright, Australia to intensive care in a regional hospital. Bright is a small town with a population of 2000, surrounded by forest, in which there are many native parrots.

Investigation revealed that nine men had been admitted to Bright hospital with severe flu-like illness in the previous 6 weeks, five of

Results

15 men and one woman met the case definition. All confirmed cases reported fever and 14 (88%) reported sweats and chills; severe headache, myalgia, and cough were present in 11 (69%), and ten (63%) experienced confusion. 12 cases had chest radiographs, 11 (92%) of which showed acute changes. The pattern of onset of illness throughout the epidemic is shown in the figure.

The median ages of cases and controls were 56·5 years and 57·0 years, respectively (table 1). 15 (94%) of 16 cases compared

Discussion

Previously reported community psittacosis outbreaks have been associated with aviaries, pet shops, or poultry-processing plants.5, 6, 7, 8 Because commonly used serological tests for C psittaci may crossreact with C pneumoniae, community outbreaks without avian association may have been outbreaks of C pneumoniae. ⁹ In our study, serial blood samples from 16 patients showed closely correlating positive C psittaci infection, and necropsy showed C psittaci nucleic acid in lung tissue. These

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Psittacosis is most common in young and middle-aged adults, although it has been described in all age groups. Most patients with psittacosis have a history of contact with birds but transmission from other animals has also been reported and direct contact with animals may not be apparent (Center for Disease Control and Prevention, 2000; Knittler et al., 2014; Williams et al., 1998). Most cases of pneumonia due to C. pneumoniae are asymptomatic or mild but severe pneumonia can develop in elderly patients and those with coexisting cardiopulmonary disease and hence the pneumonia has few clinical distinguishing features (Benitez et al., 2012; Kumar & Hammerschlag, 2007), so clinical diagnosis of Chlamydia spp. as a cause of pneumonia is difficult.
We describe unanticipated detection of respiratory infection with Chlamydia trachomatis and Chlamydia psittaci after introduction of respiratory multiplex polymerase chain reaction assay that includes Chlamydiaceae family primers. We detected cases of pediatric C. trachomatis and of adult C. psittaci infection in patients with previously unrecognized risk factors. Directed testing for C. trachomatis and C. psittaci based on clinical features and risk factors alone is likely to miss the majority of infected cases.
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During this investigation we were unable to confirm any cases of C. psittaci disease in humans using serology despite repeated testing. Previous studies have demonstrated that the rises in antibody titer may take between 2 weeks and 3 months after onset and the lack of an antibody response may be due to the effect of antibiotic treatment [6]. In this study, clinical features characteristic of psittacosis, a rise in C. psittaci specific titer, albeit non-diagnostic, a clear epidemiological link, as well as the absence of an alternative diagnosis was considered sufficient evidence to avoid misclassification.
In November 2014, New South Wales Health was notified of a cluster of respiratory illness in a veterinary school. Active case finding identified another case at a local equine stud. All cases had exposure to the equine fetal membranes of Mare A. This tissue subsequently tested positive for Chlamydia psittaci using quantitative real-time polymerase chain reaction. We conducted a cohort study of the university and stud farm staff to determine risk factors for disease. Nine people were exposed to the fetal membranes of Mare A. Of these, five cases of psittacosis were identified. Two required hospital admission. Contact with birds was not associated with illness (RR = 0.5, 95% CI = 0.09–2.73). People who had direct contact with the abnormal fetal membranes were more likely to develop disease (RR = 11.77, 95% CI = 1.02–∞). The emergence of an association between horse exposure and C. psittaci infection has important implications for the prevention and control of psittacosis.
Article summary line: Investigation of an outbreak of psittacosis in a rural veterinary school demonstrates novel source of infection for psittacosis through exposure to abnormal equine fetal membranes.
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2014, New Microbes and New Infections
Following a large outbreak of community-acquired psittacosis in 2002 in residents of the Blue Mountains, New South Wales, Australia, we reviewed new cases in this area over a 7-year period from 2003 to 2009. Using the 2010 criteria from the Centers for Disease Control National Notifiable Diseases Surveillance System, 85 patients with possible psittacosis were identified, of which 48 were identified as definite or probable infection. Clinical features of these cases are summarized. In addition to Chlamydia-specific serology, specimens, where available, underwent nucleic acid testing for chlamydial DNA using real-time PCR. Chlamydophila psittaci DNA was detected in samples from 23 patients. Four of 18 specimens were culture positive. This is the first description of endemic psittacosis, and is characterized in this location by community-acquired psittacosis resulting from inadvertent exposure to birds. The disease is likely to be under-diagnosed, and may often be mistaken for gastroenteritis or meningitis given the frequency of non-respiratory symptoms, particularly without a history of contact with birds. Clinical characteristics of endemic and outbreak-associated cases were similar. The nature of exposure, risk factors and reasons for the occurrence of outbreaks of psittacosis require further investigation.
Zoonotic atypical pneumonia due to Chlamydophila psittaci: First reported psittacosis case in Taiwan
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Human psittacosis caused by Chlamydophila psittaci is one of the most common zoonotic atypical pneumonias featuring pulmonary as well as extrapulmonary infections. Most of the cases involve avian contact history especially with psittacine birds. Herein we report a 44-year-old male patient displaying atypical pneumonia symptoms of intermittent fever, dry cough, chest pain, dyspnea, headache, hepatitis, and hyponatremia. He had two sick cockatiels, one of which had died a month previously. A microimmunofluorescence test was performed to check the serum antibody levels against Chlamydophila psittaci. The serum IgM titer showed positive titer of 1:256, 1:256, and 1:128 on Days 11, 23, and 43 after disease onset, respectively. His fever subsided soon and clinical symptoms improved after minocycline was administrated on Day 12. The psittacosis case was confirmed by history of psittacine bird contact, clinical symptoms, treatment response, and positive IgM titer. To our knowledge, this is the first report of a psittacosis case in Taiwan.

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Early ReportCommunity outbreak of psittacosis in a rural Australian town

Summary

Background

Methods

Findings

Interpretation

Introduction

Section snippets

Methods

Results

Discussion

Lancet

Chlamydia shedding by four species of wild birds

Avian Dis

The ecology of psittacosis and ornithosis

Medicine

Genetic diversity and identification of the chlamydial 60 Kilodalton cysteine-rich outer membrane protein gene

J Clin Microbiol

An epidemic of avian and human psittacosis

Arch Intern Med

Early Report
Community outbreak of psittacosis in a rural Australian town