Wild and domestic bird faeces likely source of psittacosis transmission-A case-control study in Sweden, 2014-2016

Compare Clinical Characteristics of Psittacosis Pneumonia in 35 Patients and of Non Psittacosis Bacterial Pneumonia in 46 Patients

Background

We aimed to describe the difference between Chlamydia psittaci pneumonia group and non C. psittaci bacterial pneumonia group in community acquired pneumonia in this single-center clinical study.

Methods

We collected the data of 35 patients with C. psittaci pneumonia cases and 46 patients with non C. psittaci bacterial pneumonia cases diagnosed with metagenomic next-generation sequencing assays from February 2019 to December 2021 in Huaihua First People's Hospital in China.

Results

In the C. psittaci pneumonia group, 35 patients (100%) had a chance of exposure to poultry or birds, and their body temperature was greater than or equal to 39.0°C. The other common symptoms were a slow pulse (68.6%), cough (65.7%), expectoration (54.3%), chills (51.4%) and a shortness of breath (37.1%). Laboratory tests showed that >90% of the cases had markedly elevated infection indicators, and 97.1% of the cases had markedly declined calcium. The most common imaging finding was patchy shadows (94.3%), pleural effusion (68.6%), bilateral in 54.3% (n = 19) and unilateral in 45.7% (n = 16) participants, and 51.4% (n = 18) of cases met the criteria for severe pneumonia. In the non C. psittaci bacterial pneumonia group, 18 patients (39.1%) had a chance of exposure to poultry or birds, and 11 patients (23.9%) body temperature was greater than or equal to 39.0°C. Laboratory tests showed that >67% of cases had a mildly elevated infection indicators, and mildly declined serum albumin.

Conclusion

The following characteristics are more likely to help distinguish C. psittaci pneumonia from non C. psittaci bacterial pneumonia. Including had a chance of exposure to poultry or birds, high fever, exhibit chills, expectoration, relatively slow pulse, and progress into severe pneumonia. Percentage of neutrophils, C-reactive protein, procalcitonin, lactate dehydrogenase, and myoglobin levels are higher. Blood calcium and corrected calcium are lower. Chest CT showed pleural effusion, pericardial effusion, and mediastinal lymphadenopathy.

SNP-based high-resolution typing of Chlamydia psittaci from humans and wild birds in Sweden: circulation of the Mat116 genotype reveals the transmission mode to humans

The incidence of Chlamydia psittaci respiratory tract infections in humans has increased in Sweden in recent years. This study aimed to identify the transmission route by genotyping C. psittaci from infected humans and birds. 42 human C. psittaci samples and 5 samples from C. psittaci-infected birds were collected. Genotyping was performed using ompA sequencing, Multi-locus sequence typing, and/or SNP-based high-resolution melting-PCR. Epidemiological data was also collected, and a phylogenetic analysis was conducted. Analysis of ompA provided limited resolution, while the SNP-based PCR analysis successfully detected the Mat116 genotype in 3/5 passerine birds and in 26/29 human cases, indicating a high prevalence of this genotype in the human population. These cases were associated with contact with wild birds, mainly through bird feeding during winter or other outdoor exposure. Human cases caused by other genotypes (psittacine and pigeon) were less common and were linked to exposure to caged birds or pigeons. The SNP-genotype Mat116 is rare, but predominated in this study. The use of SNP-based PCR provided a better understanding of the C. psittaci transmission from birds to humans compared to ompA analysis. In Sweden, human psittacosis appears mainly to be transmitted from garden birds during bird feeding in the winter season.

Chlamydia psittaci in garden birds in Sweden

Increased numbers of human infections with Chlamydia psittaci have been associated with bird feeding activities in southern Sweden. Information on occurrence and genotype of C. psittaci in garden birds in Sweden is required to corroborate this finding but data are limited. Additionally, pathogenicity of C. psittaci for garden birds is poorly understood. In this study, C. psittaci infection was investigated in 275 garden birds representing 22 species submitted for wildlife disease surveillance between 2009 and 2019. PCR was used to detect C. psittaci DNA in liver and lung. Positive samples were genotyped, additional PCR was performed on feces, and tissues were examined microscopically. C. psittaci was found in six (2.2 %) birds; three great tits (Parus major), two feral (Columba livia) and one wood pigeon (Columba palumbus). Two great tits and the wood pigeon had inflammatory lesions associated with C. psittaci. In the great tits and wood pigeon, C. psittaci genotype A, the cause of most human cases, was detected. Genotype B, considered endemic in pigeons, was detected in the feral pigeons. Low incidence of C. psittaci in dead Swedish garden birds was similar to studies on apparently healthy Swedish birds. Pathological findings were consistent with C. psittaci being fatal in half of the positive birds, which also had higher bacterial loads in feces. This highlights the risk for human infection via infected garden birds, especially regarding great tits and pigeons.

Prevalence and Risk Factors of Avian Chlamydiosis Detected by Polymerase Chain Reaction in Psittacine Birds in Thailand

This study surveyed avian chlamydiosis, with the aim to estimate the prevalence and potential risk factors associated with Chlamydia psittaci infection in psittacine birds kept as domestic pets in Thailand. Oropharyngeal swabs were collected from 120 psittacine birds that were randomly selected from hospitals in the central (Bangkok) and northeastern regions (Khon Kaen) of Thailand between 2019 and 2021. The oropharyngeal swabs were subject to polymerase chain reaction testing to detect the C psittaci ompA gene. The prevalence of C psittaci was 2.5% (3/ 120, 95% confidence interval = 0.3-5.3). Of the 3 positive birds, 1 was a Forpus parrot (Forpus species)(CP43TH) and 1 was an African grey parrot (Psittacus erithacus)(CP49TH) from Bangkok; both were juvenile birds with clinical signs of disease. The third positive bird (CP12TH) was a subclinical adult sun conure (Aratinga solstitialis) from Khon Kaen. Two sequences of samples that were previously identified in human psittacosis cases (accession numbers MK032053.1 and HM450409.1) were also examined. Since there was a low number of infected birds, potential associations between C psittaci infection and various environmental variables (eg, cage cleaning, synanthropic birds, quarantine of new birds, and overcrowding) were assessed by Fisher exact tests. This study provides estimates of the prevalence and potential risk factors associated with C psittaci infection in psittacine birds from central (Bangkok) and the northeastern regions (Khon Kaen) of Thailand. The detection of C psittaci in captive psittacine birds demonstrates that there is a possibility for bird-to-bird transmission as well as some zoonotic potential for the human caretakers of these birds. Furthermore, larger-scale studies should be conducted to confirm these findings.

A Review of Chlamydial Infections in Wild Birds

The Chlamydia are a globally distributed genus of bacteria that can infect and cause disease in a range of hosts. Birds are the primary host for multiple chlamydial species. The most well-known of these is Chlamydia psittaci, a zoonotic bacterium that has been identified in a range of wild and domesticated birds. Wild birds are often proposed as a reservoir of Chlamydia psittaci and potentially other chlamydial species. The aim of this review is to present the current knowledge of chlamydial infections in wild avian populations. We focus on C. psittaci but also consider other Chlamydiaceae and Chlamydia-related bacteria that have been identified in wild birds. We summarise the diversity, host range, and clinical signs of infection in wild birds and consider the potential implications of these infections for zoonotic transmission and avian conservation. Chlamydial bacteria have been found in more than 70 species of wild birds, with the greatest chlamydial diversity identified in Europe. The Corvidae and Accipitridae families are emerging as significant chlamydial hosts, in addition to established wild hosts such as the Columbidae. Clarifying the effects of these bacteria on avian host fitness and the zoonotic potential of emerging Chlamydiales will help us to understand the implications of these infections for avian and human health.

Occurrence of Chlamydiaceae in Raptors and Crows in Switzerland

Bacteria of the family Chlamydiaceae are globally disseminated and able to infect many bird species. So far, 11 species of Chlamydia have been detected in wild birds, and several studies found chlamydial strains classified as genetically intermediate between Chlamydia (C.) psittaci and C.abortus. Recently, a group of these intermediate strains was shown to form a separate species, i.e., C.buteonis. In the present study, 1128 samples from 341 raptors of 16 bird species and 253 corvids representing six species were examined using a stepwise diagnostic approach. Chlamydiaceae DNA was detected in 23.7% of the corvids and 5.9% of the raptors. In corvids, the most frequently detected Chlamydia species was C.psittaci of outer membrane protein A (ompA) genotype 1V, which is known to have a host preference for corvids. The most frequently detected ompA genotype in raptors was M56. Furthermore, one of the raptors harbored C.psittaci 1V, and two others carried genotype A. C.buteonis was not detected in the bird population investigated, so it remains unknown whether this species occurs in Switzerland. The infection rate of Chlamydiaceae in corvids was high compared to rates reported in other wild bird species, but neither Chlamydiaceae-positive corvids nor raptors showed overt signs of disease. Since the Chlamydiaceae of both, raptors and crows were identified as C.psittaci and all C.psittaci genotypes are considered to be zoonotic, it can be suggested that raptors and crows pose a potential hazard to the health of their handlers.