Chlamydia psittaci(psittacosis) as a cause of community-acquired pneumonia: a systematic review and meta-analysis

Abstract

Psittacosis is a zoonotic infectious disease caused by the transmission of the bacterium Chlamydia psittaci from birds to humans. Infections in humans mainly present as community-acquired pneumonia (CAP). However, most cases of CAP are treated without diagnostic testing, and the importance of C. psittaci infection as a cause of CAP is therefore unclear. In this meta-analysis of published CAP-aetiological studies, we estimate the proportion of CAP caused by C. psittaci infection. The databases MEDLINE and Embase were systematically searched for relevant studies published from 1986 onwards. Only studies that consisted of 100 patients or more were included. In total, 57 studies were selected for the meta-analysis. C. psittaci was the causative pathogen in 1·03% (95% CI 0·79-1·30) of all CAP cases from the included studies combined, with a range between studies from 0 to 6·7%. For burden of disease estimates, it is a reasonable assumption that 1% of incident cases of CAP are caused by psittacosis.

Animal sources for zoonotic transmission of psittacosis: a systematic review

“…Community-acquired pneumonia (CAP) is the most important presentation of human psittacosis, but microbiological testing for psittacosis in a pneumonia patient is often not incorporated in routine diagnostics. Due to the non-specific symptoms and the fact that often only severely ill patients are being tested for C. psittaci, the disease is likely underdiagnosed and underreported [18][19][20][21][22]. A recent review and meta-analysis of CAP etiological studies estimated that in 1.03% (95% CI: 0.79-1.30) of all CAP cases from the included studies combined, C. psittaci was the causative pathogen, with a range between studies from 0 to 6.7% [21].…”

“…Due to the non-specific symptoms and the fact that often only severely ill patients are being tested for C. psittaci, the disease is likely underdiagnosed and underreported [18][19][20][21][22]. A recent review and meta-analysis of CAP etiological studies estimated that in 1.03% (95% CI: 0.79-1.30) of all CAP cases from the included studies combined, C. psittaci was the causative pathogen, with a range between studies from 0 to 6.7% [21]. Based on this result, an estimated 4.4% (95% CI: 1.6-8.2%) of symptomatic cases were notified in the Netherlands over the period 2012-2014 [20].…”

Recent history of psittacosis in Australia: expanding our understanding of the epidemiology of this important globally distributed zoonotic disease

“…It is likely that human infections are underdiagnosed as: (i) most cases of community acquired pneumonia receive treatment without testing; 16 (ii) infections are misdiagnosed; 17 and/or (iii) specific molecular testing for C. psittaci and other chlamydial species, based on clinical features and risk factors alone, may mean that infections are missed. It is likely that human infections are underdiagnosed as: (i) most cases of community acquired pneumonia receive treatment without testing; 16 (ii) infections are misdiagnosed; 17 and/or (iii) specific molecular testing for C. psittaci and other chlamydial species, based on clinical features and risk factors alone, may mean that infections are missed.…”

“…As in the rest of the world, psittacosis in Australia is still considered to be a rare but important cause of zoonotic disease. It is likely that human infections are underdiagnosed as: (i) most cases of community acquired pneumonia receive treatment without testing; 16 (ii) infections are misdiagnosed; 17 and/or (iii) specific molecular testing for C. psittaci and other chlamydial species, based on clinical features and risk factors alone, may mean that infections are missed. 18 While C. psittaci zoonoses resulting from direct contact with birds should still be considered the most important risk factor for psittacosis in humans, the results of recent Australian studies reveal that primary care physicians and public health authorities need to consider carefully alternative transmission routes for this zoonotic agent in patients with suspected pneumonia of unknown origin.…”

Customs officers in relation to viral infections, tuberculosis, psittacosis and environmental health risk (Review)

“…Psittacosis -the term 'psittacosis' is derived from the Hellenistic ancient Greek word for parrots, 'psittakos' (ψιττακός) or 'psittaki' (ψιττάκη) -is a zoonotic infectious disease caused by the obligatory intracellular bacterium Chlamydia psittaci; in humans, Chlamydia psittaci can cause infection mainly presented as community-acquired pneumonia (24,25). This bacterium can infect parrots, parakeets, canaries and other avian species (e.g., turkeys, pigeons and ducks) and is considered a financially significant pathogen for poultry farming.…”