History and exam

Key diagnostic factors

common

presence of risk factors

Contact with birds, for example among pet bird owners, people who work in zoos or pet shops, veterinarians, poultry and wildlife workers, and diagnostic laboratorians, appears to be the primary risk factor.[13]

illness in other family members

Spread can occur from pet birds to many members of a family.

Other diagnostic factors

common

fever

Can be low grade and of gradual onset.

malaise

Patients may have 1 to 2 weeks of gradual onset of malaise.[28][34]

headache

Patients may have 1 to 2 weeks of gradual onset of headache.[28][34]

cough

Usually non-productive.

sore throat

Can be mild to severe.

rales

Consistent with pneumonia.

tachypnoea

Variable, dependent on extent of lung involvement.

pharyngitis

Variable presentation, with no distinguishing characteristics.

conjunctivitis

Chlamydia psittaci has been associated with acute and chronic follicular conjunctivitis. The only finding may be unilateral or bilateral diffuse erythema of the sclera, with or without a discharge. Patients with ocular infection often complain of a foreign body sensation.[3][4]

uncommon

hepatomegaly

Diffusely enlarged liver with pain on palpation but no appreciable masses. It is more common in cases of systemic illness.

confusion

Occasionally present.

tachycardia

Occasionally present.

splenomegaly

Diffusely enlarged spleen with pain on palpation is occasionally present.

Risk factors

strong

exposure to infected birds and mammals

Contact with birds, for example among pet bird owners, people who work in zoos or pet shops, veterinarians, poultry and wildlife workers, and diagnostic laboratorians, appears to be the primary risk factor.[13] The organism is spread by direct contact with infected secretions, including faeces, nasal discharge, and tissue, or by aerosolised particles.[5][20]

Outbreaks have been observed on duck, turkey, and other poultry farms, among abattoir workers, and from exposure to feral pigeons and non-psittacine birds.[1][5][6][16][17][18][19][20][21][22] There have also been reports of outbreaks associated with bird shows and in veterinary teaching hospitals.[23][24][25]

Owners of exotic and other pet birds or mammals, and those exposed to feral animals that are acutely or chronically infected with Chlamydia psittaci, are also highly susceptible to infection.[1][5][20]

weak

young children

Young children are at an increased risk of infection and more severe disease if they come in contact with infected animals.[1]

older adults

Older adults are at increased risk of infection and more severe disease if they come in contact with infected animals.[1] In the US, the main age group affected is people 40 to 64 years of age; however, it is unknown whether this is due to age-related differences in susceptibility or exposure.[13]

immunocompromised

People with a compromised immune system are at increased risk of infection and more severe disease if they come in contact with infected animals.[1] However, pet birds are thought to pose a low risk to these patients.[13]

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