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. 2020 Mar 4;20(1):192.
doi: 10.1186/s12879-020-4918-y.

Animal sources for zoonotic transmission of psittacosis: a systematic review

Lenny Hogerwerf  1 , Inge Roof  2 , Marianne J K de Jong  1   3 , Frederika Dijkstra  1 , Wim van der Hoek  1
Affiliations

Animal sources for zoonotic transmission of psittacosis: a systematic review

Lenny Hogerwerf et al. BMC Infect Dis. .

Abstract

Background: Human psittacosis, caused by Chlamydia (C.) psittaci, is likely underdiagnosed and underreported, since tests for C. psittaci are often not included in routine microbiological diagnostics. Source tracing traditionally focuses on psittacine pet birds, but recently other animal species have been gaining more attention as possible sources for human psittacosis. This review aims to provide an overview of all suspected animal sources of human psittacosis cases reported in the international literature. In addition, for each animal species the strength of evidence for zoonotic transmission was estimated.

Methods: A systematic literature search was conducted using four databases (Pubmed, Embase, Scopus and Proquest). Articles were included when there was mention of at least one human case of psittacosis and a possible animal source. Investigators independently extracted data from the included articles and estimated strength of evidence for zoonotic transmission, based on a self-developed scoring system taking into account number of human cases, epidemiological evidence and laboratory test results in human, animals, and the environment.

Results: Eighty articles were included, which provided information on 136 different situations of possible zoonotic transmission. The maximum score for zoonotic transmission was highest for turkeys, followed by ducks, owls, and the category 'other poultry'. Articles reporting about zoonotic transmission from unspecified birds, psittaciformes and columbiformes provided a relatively low strength of evidence. A genotypical match between human and animal samples was reported twenty-eight times, including transmission from chickens, turkeys, guinea fowl, peafowl, pigeons, ducks, geese, songbirds, parrot-like birds and owls.

Conclusions: Strong evidence exists for zoonotic transmission from turkeys, chickens and ducks, in addition to the more traditionally reported parrot-like animal sources. Based on our scoring system, the evidence was generally stronger for poultry than for parrot-like birds. Psittaciformes should not be disregarded as an important source of human psittacosis, still clinicians and public health officials should include poultry and birds species other than parrots in medical history and source tracing.

Keywords: Animal sources; Chlamydia psittaci; Psittacosis; Strength of evidence; Zoonosis.

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Conflict of interest statement

The authors declare that they have no competing interests.

Figures

Fig. 1
Fig. 1
Flow chart of literature search and selection of articles
Fig. 2
Fig. 2
Distribution of strength of evidence across different animal categories. The lower whisker includes the first 25% of scores (first quartile); the box includes the second and third quartile separated by the median and the top whisker represents the last quartile of the scores. Outliers were not excluded because results were not within a normal distribution and outliers are of particular interest for this review. Therefore, the upper end of the top whisker represents the maximum score and the lower end of the bottom whisker represents the minimum score. * geese, guinea fowl, pheasants, peacock. ** strigiformes, musophagiformes. *** horse, cattle, pig, goat, sheep, fox, dog
See this image and copyright information in PMC

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