Skip directly to search Skip directly to A to Z list Skip directly to site content
CDC Home

Volume 11, Number 3—March 2005

Research

Probable Psittacosis Outbreak Linked to Wild Birds

Barbara L. Telfer*Comments to Author , Sarah A. Moberley†, Krishna P. Hort†, James M. Branley‡, Dominic E. Dwyer§, David J. Muscatello*, Patricia K. Correll*, John England¶, and Jeremy M. McAnulty*
Author affiliations: *New South Wales (NSW) State Department of Health, NSW, Australia; †Wentworth Public Health Unit, NSW, Australia; ‡Nepean and Blue Mountains Pathology Service, NSW, Australia; §Westmead Hospital, NSW, Australia; ¶Blue Mountains District ANZAC Memorial Hospital, NSW, Australia

Main Article

Table 1

Potential risk factors for psittacosis among case-patients and controls in the Blue Mountains outbreak, Australia

Potential risk factor Case-patients, 
N = 48 (%) Controls, 
N = 310 (%) Crude OR (95% CI)* p value
Age group (y)
15–49 10 (21) 155 (50) Referent
50–64 27 (56) 89 (29) 4.7 (2.2–10.2) 0.0007
65–75 11 (23) 66 (21) 2.6 (1.0–6.4) 0.04
Male sex 30 (63) 125 (40) 2.5 (1.3–4.6) 0.005
Resident of the upper Blue Mountains 42 (88) 104 (34) 13.9 (5.7–33.7) <0.0001
History of asthma 1 (2) 64 (21) 0.08 (0.01–0.6) 0.0009
Employed 28 (58) 192 (62) 0.9 (0.5–1.6) 0.6
Outdoor employment 7 (15) 39 (13) 1.2 (0.5–2.8) 0.64
Bird contact
Contact with caged or domestic birds 3 (6) 56 (18) 0.3 (0.1–1.0) 0.04
Contact with poultry birds 3 (6) 28 (9) 0.7 (0.2–2.3) 0.80
Visit to pet shop 9 (20) 39 (13) 1.6 (0.7–3.6) 0.25
Visit to aviary 0 (0) 3 (1) Incalculable 1.0
Visit to zoo 0 (0) 3 (1) Incalculable 1.0
Visit to poultry farm 0 (0) 4 (1) Incalculable 1.0
Level of contact with free-ranging (wild) birds†
No contact 9 (19) 137 (44) Referent
Only indirect contact‡ 15 (31) 121 (39) 1.9 (0.8–4.5) 0.15
Any direct contact§ 24 (50) 52 (17) 7.0 (3.1–16.1) <0.0001
Yard exposures
Lawn mowing
Did not mow lawn 21 (44) 170 (55) Referent
Only mowed lawn with a grass catcher 4 (8) 75 (24) 0.4 (0.1–1.3) 0.14
Mowed lawn without a grass catcher 23 (48) 65 (21) 2.9 (1.5–5.5) 0.0017
Mowed lawn without a catcher for >1 hour 15 (31) 20 (6) 6.6 (3.1–14.1) <0.0001
Pruning, cutting back branches 21 (45) 141 (47) 1.0 (0.5–1.7) 0.88
Potting or weeding 15 (31) 155 (50) 0.5 (0.2–0.9) 0.02
Watering yard 24 (50) 157 (52) 0.9 (0.5–1.7) 0.88
Raking yard 21 (45) 106 (35) 1.5 (0.8–2.8) 0.25
Soft landscaping 12 (25) 97 (31) 0.7 (0.4–1.5) 0.40
Hard landscaping 5 (10) 17 (5) 2.0 (0.7–5.7) 0.19
Mulching 9 (20) 56 (18) 1.1 (0.5–2.4) 0.84
Using compost 13 (27) 49 (16) 2.0 (1.0–4.0) 0.07
Using fertilizer 9 (20) 52 (17) 1.2 (0.5–2.6) 0.68
Home renovations or demolition 4 (9) 29 (9) 0.9 (0.3–2.7) 1.00
Bushwalking 13 (28) 91 (30) 1.0 (0.5–1.9) 1.00
Current or ex-smoker 23 (48) 141 (45) 1.1 (0.6–2.0) 0.76
General health self-rating
Excellent to very good 23 (48) 182 (59) Referent
Good to fair 18 (37) 111 (36) 1.3 (0.7–2.5) 0.46
Poor to very poor 7 (15) 17 (5) 3.3 (1.2–8.7) 0.02
Yard attached to residence 48 (100) 302 (97) Incalculable 0.61
Lived adjacent to bushland 33 (68) 184 (59) 1.5 (0.8–2.9) 0.27
Lived in a house 48 (100) 305 (98) Incalculable 1.00
Lived in the Blue Mountains <5 years 11 (23) 38 (12) 2.1 (1.0–4.5) 0.07

*OR, odds ratio; CI, confidence interval.
†Chi-square test for linear trend = 24.5, p value < 0.001.
‡Indirect contact only with free-ranging (wild) birds: watching bird at bird feeder, watching birds in yard, seeing dead birds, watching birds in bird bath, bird flying in house.
§Any direct contact with free-ranging (wild) birds: catching birds, clipping birds’ feathers, tending to sick birds, touching birds’ feathers, cleaning up or touching birds’ nest, cleaning up or touching bird droppings, handling dead birds.

Main Article

Top of Page

USA.gov: The U.S. Government's Official Web PortalDepartment of Health and Human Services
Centers for Disease Control and Prevention   1600 Clifton Rd. Atlanta, GA 30333, USA
800-CDC-INFO (800-232-4636) TTY: (888) 232-6348 - Contact CDC–INFO