Outbreak of psittacosis in a group of women exposed to Chlamydia psittaci-infected chickens

Chlamydia gallinacea in Brazilian backyard chicken farms

Avian chlamydiosis is a bacterial infectious disease of birds, considered until recently caused only by Chlamydia psittaci, that now includes the newly described species C. buteonis, C. avium, and C. gallinacea, associated with several avian hosts. Since its recognition as a species in 2014 and having chickens as one of its main hosts, C. gallinacea has already been described in backyard poultry on all continents. The present study aimed to survey by molecular techniques the presence and species of Chlamydia spp. in backyard chickens from three states of the southern region of Brazil (Paraná-PR, Santa Catarina-SC, and Rio Grande do Sul-RS). DNA extracted from cloacal swab samples were tested by polymerase chain reaction (PCR) for different species of Chlamydia, namely Chlamydiaceae (23 S rRNA gene), C. psittaci (ompA gene), C. avium (enoA gene) and C. gallinacea (gidA and enoA genes). The 16 S rRNA gene was used for sequencing and phylogenetic analysis. A total of 582 backyard chicken samples were collected and grouped in 238 pools, from 134 properties in 59 municipalities. Chlamydiaceae was detected in 25.2% (60/238) of the samples, in 38.8% (52/134) of the properties and in 66.1% (39/59) of the municipalities. None of the samples yielded positive PCR results for C. psittaci or C. avium. For C. gallinacea, the overall percentage was 16.3% (39/238) according to the results of gidA and enoA genes. Sequence analysis confirmed that the samples corresponded to C. gallinacea. This is the first report of C. gallinacea in Brazil.

Belgian Cross-Sectional Epidemiological Study on Zoonotic Avian Chlamydia spp. in Chickens

Chlamydia psittaci, Chlamydia gallinacea, and Chlamydia abortus are the most common Chlamydia spp. in chickens and have a confirmed or suggested zoonotic potential. No recent data are available on their prevalence and impact in the Belgian chicken industry or in the recreational chicken branch. Therefore, a cross-sectional epidemiological study was executed where samples were collected from both factory-farmed and backyard chickens. More specifically, pharyngeal chicken swabs were obtained from 20 chicken farms, 5 chicken abattoirs, and 38 different backyard locations and were analyzed using species-specific Polymerase Chain Reactions (PCRs) for the presence of the three avian Chlamydia spp. To investigate their zoonotic potential, samples were simultaneously collected from 54 backyard chicken caretakes and 37 professional chicken caretakers or abattoir employees and analyzed using species-specific PCRs as well. This study confirmed the presence of DNA of all three Chlamydia species in both the chicken industry and backyard settings. Chlamydia psittaci was the most prevalent in the industry chickens (11.0%), whereas Chlamydia gallinacea was the dominant species in the backyard chickens (14.5%). Chlamydia abortus infections were more common in the commercial chickens (9.0%) compared to the backyard chickens (2.6%). The DNA of all three species was also detected in humans (3.9% Chlamydia psittaci, 2.9% Chlamydia gallinacea, and 1.0% Chlamydia abortus).

Chlamydia psittaci seropositivity in workers exposed to birds and review of the literature: Evidence of circulation in Antioquia

Introduction

Psittacosis is a zoonotic disease caused by Chlamydia psittaci, a bacterium classified as an agent with bioterrorist potential. It has caused multiple outbreaks in exposed poultry workers around the world. Colombia has no epidemiological follow-up of the infection and a big knowledge gap.

Objectives

To determine the antibodies’ frequency against C. psittaci in workers with occupational exposure to birds and to review the literature on studies conducted in Colombia.

Materials and methods

We conducted a cross-sectional descriptive study with analytical intent on workers in contact with birds and reviewed the related literature in Colombia. IgM and IgG serum antibodies against C. psittaci were detected by microimmunofluorescence. The sociodemographic and exposure characteristics were expressed as frequencies and summary measures. Associated factors were explored by bivariate and multivariate analysis. The scientific and gray literature review was done with a structured search.

Results

We analyzed 54 workers in contact with birds. Antibody prevalence was 31.5%. Slaughtering and evisceration by non-veterinarians was a risk factor for antibody presence. There are only four previous studies on C. psittaci in Colombia.

Conclusions

Here, we present the first evidence of C. psittaci circulation among workers exposed to birds in Antioquia and the second report in the country. These findings contribute to the “One Health” public health strategy.

Psittacosis: An Underappreciated and Often Undiagnosed Disease

The bacterial agent Chlamydia psittaci, and the resulting disease of psittacosis, is a little-known and underappreciated infectious disease by healthcare practitioners and in public health in general. C. psittaci infections can cause significant psittacosis outbreaks, with person-to-person transmission documented in the last decade. In this publication, we review the pathogen and its disease, as well as examine the potential for genetic manipulation in this organism to create a more deadly pathogen. Recent disease surveys indicate that currently, the highest incidences of human disease exist in Australia, Germany and the UK. We recommend the universal public health reporting of C. psittaci and psittacosis disease and increasing the promotion of public health awareness.

Epidemiological and clinical characteristics of psittacosis among cases with complicated or atypical pulmonary infection using metagenomic next-generation sequencing: a multi-center observational study in China

BACKGROUND

Chlamydia psittaci (C. psittaci) causes parrot fever in humans. Development of metagenomic next-generation sequencing (mNGS) enables the identification of C. psittaci.

METHODS

This study aimed to determine the epidemiological and clinical characteristics of parrot fever cases in China. A multi-center observational study was conducted in 44 tertiary and secondary hospitals across 14 provinces and municipalities between April 2019 and October 2021.

RESULTS

A total of 4545 patients with complicated or atypical pulmonary infection were included in the study, among which the prevalence of C. psittaci was determined to be 2.1% using mNGS. The prevalence of C. psittaci was further determined across demographic groups and types of specimens. It was significantly higher in patients with senior age (2.6% in those > 50 years), winter-spring (3.6%; particularly in December, January, and February), and southwestern (3.4%) and central and southern China (2.7%) (each P < 0.001). Moreover, the prevalence was the highest in bronchoalveolar lavage fluid (BALF) (2.9%), compared with sputum (1.1%) and peripheral blood specimens (0.9%). Additionally, co-infection of principal microorganisms was compared. Certain microorganisms were more likely to co-infect in parrot fever cases, such as Candida albicans in BALF (26.7%) and peripheral blood (6.3%), compared with non-parrot fever cases (19.7% and 1.3%); however, they did not significantly differ (each P > 0.05).

CONCLUSION

Parrot fever remains low in patients with complicated or atypical pulmonary infection. It is likely to occur in winter-spring and southwestern region in China. BALF may be the optimal specimen in the application of mNGS. Co-infection of multiple microorganisms should be further considered.

Whole Genome Sequencing and Comparative Genomic Analysis of Chlamydia gallinacea Field Strains Isolated from Poultry in Poland

Chlamydia gallinacea is an intracellular bacterium belonging to the Chlamydiaceae family. Poultry is considered to be the major reservoir of this agent, which has worldwide distribution and a particularly consistent worldwide occurrence in chicken flocks. The bacterium has been linked to respiratory disease in humans but without definitive confirmation; nevertheless, while it has not been proved to be the cause of human respiratory disease, a recent report from Italy verified its bird-to-human transmission. This aspect being significant for public health, more research is needed to gain insight into the infection biology of C. gallinacea. In this study, the genomes of eleven novel C. gallinacea field strains from different regions of Poland were analyzed comparatively. It was confirmed that C. gallinacea strains are closely related, with at least 99.46% sequence identity. They possess a conservative genome structure involving the plasticity zone with a complete cytotoxin, the type three secretion system, inclusion membrane proteins, polymorphic membrane proteins, hctA and hctB histone-like proteins, and the chlamydial protease-like activating factor exoenzyme, as well as plasmids. Genetic diversity seems to be restricted. However, some genetic loci, such as ompA and multi-locus sequence typing target genes, are diverse enough to enable high-resolution genotyping and epidemiological tracing.

Prostatitis as initial manifestation of Chlamydia psittaci pneumonia diagnosed by metagenome next-generation sequencing: A case report

Chlamydia psittaci (C. psittaci) pneumonia is a zoonotic infectious disease caused by C. psittaci, which is often underdiagnosed. The application of metagenomic next-generation sequencing (mNGS) provides an unbiased method for the detection of unknown pathogens. A 46-year-old man received empirical treatment with piperacillin-tazobactam and moxifloxacin after an initial diagnosis of prostatitis and pneumonia. However, he experienced recurrent symptoms and a cough, and a chest computed tomography (CT) showed aggravated pulmonary inflammation. Upon further questioning, the patient recalled a history of contact with pigeons, and a bronchoscope alveolar lavage fluid analysis with mNGS suggested C. psittaci infection. Following treatment with doxycycline, the patient's symptoms were rapidly alleviated, and chest CT showed pulmonary lesions absorption. The patient was followed up for 1 month without any discomfort. This case highlights that initial manifestations of C. psittaci pneumonia may present with atypical symptoms such as prostatitis. Furthermore, mNGS can be a useful tool for the detection of rare or unknown pathogens such as C. psittaci.

Prevalence of New and Established Avian Chlamydial Species in Humans and Their Psittacine Pet Birds in Belgium

The presence and zoonotic transfer of four different avian Chlamydia spp. was assessed in an epidemiological study in a psittacine bird population and its owners. Fecal swabs from 84 pet birds and pharyngeal swabs from 22 bird owners were collected from 21 locations in Flanders. Samples were examined using established and novel PCR platforms combined with culture on PCR-positive samples. Chlamydiaceae DNA was detected in 33 of 84 (39.3%) birds. The predominant part of the avian infections could be attributed to C. psittaci (22 of 84; 26.2%), followed by C. avium (11 of 84; 13.1%). C. gallinacea and C. abortus were not detected in birds or humans. C. psittaci was the only species detected in pet bird owners (4 of 22; 18.2%), stressing its zoonotic importance. This study showed that C. psittaci and the more recently discovered novel avian species C. avium are undoubtedly present in the Flemish psittacine bird population. Our results justify additional research in a larger psittacine bird population and its owners, focusing on C. psittaci and C. avium. In the meantime, increased awareness among pet bird owners and the implementation of preventive measures in the pet bird industry is advised to limit the circulation of established and novel emerging avian chlamydial species.

Human-to-human transmission of Chlamydia psittaci in China, 2020: an epidemiological and aetiological investigation

BACKGROUND

Chlamydia psittaci can infect a wide range of avian species, occasionally causing psittacosis (also known as parrot fever) in humans. Most human psittacosis cases are associated with close contact with pet birds or poultry. In December, 2020, an outbreak of severe community-acquired pneumonia of unknown aetiology was reported in a hospital in Shandong province, China, and some of the patients' close contacts had respiratory symptoms. Our aims were to determine the causative agent of this epidemic and whether there had been human-to-human transmission.

METHODS

For this epidemiological and aetiological investigation study, we enrolled patients who had community-acquired pneumonia confirmed by chest CT at two local hospitals in Shandong Province in China. We collected sputum, bronchoalveolar lavage fluid, and nasopharyngeal swab samples from participants and detected pathogens by surveying for 22 target respiratory microbes using a commercial assay, followed by metagenomic next-generation sequencing, specific nested PCR, and qPCR tests. We excluded individuals who were C psittaci-negative on both tests. We recruited close contacts of the C psittaci-positive patients, and tested nasopharyngeal swabs from the close contacts and samples from ducks from the processing plant where these patients worked. We then integrated the epidemiological, clinical, and laboratory data to reveal the potential chain of transmission of C psittaci that characterised this outbreak.

FINDINGS

Between Dec 4 and 29, 2020, we used metagenomic next-generation sequencing and different PCR-based approaches to test 12 inpatients with community-acquired pneumonia, of whom six (50%) were workers at a duck-meat processing plant and two (17%) were unemployed people, who were positive for C psittaci and enrolled in this study. We contacted 61 close contacts of the six patients who worked at the duck-meat processing plant, of whom 61 (100%) were enrolled and tested, and we determined that the community-acquired pneumonia outbreak was caused by C psittaci. Within the outbreak cluster, 17 (77%) of 22 participants had confirmed C psittaci infections and five (23%) of 22 participants were asymptomatic C psittaci carriers. The outbreak had begun with avian-to-human transmission, and was followed by secondary and tertiary human-to-human transmission, which included transmission by several asymptomatic carriers and by health-care workers. In addition, some of the participants with confirmed C psittaci infection had no identified source of infection, which suggested cryptic bacterial transmission.

INTERPRETATION

Our study data might represent the first documented report of human-to-human transmission of C psittaci in China. Therefore, C psittaci has the potential to evolve human-to-human transmission via various routes, should be considered an elevated biosecurity and emergent risk, and be included as part of the routine diagnosis globally, especially for high-risk populations.

FUNDING

Academic Promotion Programme of Shandong First Medical University, National Science and Technology Major Project, ARC Australian Laureate Fellowship.

Clinical Characteristics of Chlamydia psittaci Pneumonia Infection in Central South China

Introduction

Chlamydia psittaci pneumonia has been a global public health hotspot in recent years. Although some scattered cases of C. psittaci pneumonia have been reported, there is a lack of large case studies worldwide.

Methods

In this multicenter, observational study, we recruited all consecutive patients with confirmed C. psittaci pneumonia from October 4, 2018, to October 23, 2020, in nine tertiary general hospitals in Central-South China. Epidemiologic and clinical data from patients’ electronic medical records were collected and analyzed.

Results

One hundred and sixteen patients with C. psittaci pneumonia were included in the study. The mean age was 59.7 years. Fever (96.6%) and cough (65.5%) were the most common clinical symptoms. Most patients presented with an increase in the proportion of neutrophils, neutrophil to lymphocyte ratio, LDH, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and a significant decrease in lymphocytes. The main CT lung findings were consolidation (81%) and pleural effusion (35.3%), and bilateral lung consolidation was mainly found in severe patients. Chlamydia psittaci DNA was detected in BALF (bronchoalveolar lavage fluid) or blood samples by metagenomic next-generation sequencing (mNGS) in all patients. Use of quinolone was associated with shorter length of hospital stay and fever duration after antibiotic use. Multivariate logistic regression analysis indicated that respiratory support was associated with both severe pneumonia and in-hospital death.

Conclusions

The clinical phenotype of C. psittaci pneumonia is complex and variable. mNGS is helpful in the diagnosis and treatment of C. psittaci pneumonia, and early treatment with quinolone may benefit patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-022-00662-4.

Occurrence of Chlamydiae in Corvids in Northeast Italy

Simple Summary

The continuous improvement of next-generation sequencing techniques has led to an expansion of the number of Chlamydia species, as well as their host range. Recent studies performed on wild birds have detected Chlamydia strains with characteristics intermediate between Chlamydia psittaci and Chlamydia abortus. In this study, 12/108 corvids tested positive for Chlamydia by real-time PCR. Molecular characterisation at the species level was possible for eight samples, with one positive for C. psittaci and seven for C. abortus. Considering the well-known zoonotic role of C. psittaci and that a potential zoonotic role of avian C. abortus strains cannot be excluded, people who may have professional or other contact with wild birds should take appropriate preventive measures.

Abstract

Chlamydiaceae occurrence has been largely evaluated in wildlife, showing that wild birds are efficient reservoirs for avian chlamydiosis. In this study, DNA extracted from cloacal swabs of 108 corvids from Northeast Italy was screened for Chlamydiaceae by 23S real-time (rt)PCR. The positive samples were characterised by specific rtPCRs for Chlamydia psittaci, Chlamydia abortus, Chlamydia gallinacea, Chlamydia avium, Chlamydia pecorum and Chlamydia suis. Cloacal shedding of Chlamydiaceae was detected in 12 out of 108 (11.1%, 5.9%–18.6% 95% CI) corvids sampled. Molecular characterisation at the species level was possible in 8/12 samples, showing C. psittaci positivity in only one sample from a hooded crow and C. abortus positivity in seven samples, two from Eurasian magpies and five from hooded crows. Genotyping of the C. psittaci-positive sample was undertaken via PCR/high-resolution melting, clustering it in group III_pigeon, corresponding to the B genotype based on former ompA analysis. For C. abortus genotyping, multilocus sequence typing was successfully performed on the two samples with high DNA load from Eurasian magpies, highlighting 100% identity with the recently reported Polish avian C. abortus genotype 1V strain 15-58d44. To confirm the intermediate characteristics between C. psittaci and C. abortus, both samples, as well as two samples from hooded crows, showed the chlamydial plasmid inherent in most C. psittaci and avian C. abortus, but not in ruminant C. abortus strains. The plasmid sequences were highly similar (≥99%) to those of the Polish avian C. abortus genotype 1V strain 15-58d44. To our knowledge, this is the first report of avian C. abortus strains in Italy, specifically genotype 1V, confirming that they are actively circulating in corvids in the Italian region tested.

Chlamydia Species and Related Risk Factors in Poultry in North-Western Italy: Possible Bird-to-Human Transmission for C. gallinacea

Chlamydiaceae are obligatory intracellular bacteria causing acute and chronic diseases in animals and humans worldwide, with recently discovered species with a still unclear pathogenic potential (i.e., C. gallinacea). In Italy, Chlamydiaceae infections are underestimated both in animals and humans. To estimate the prevalence of Chlamydiaceae species in poultry and occupationally exposed workers on farm, a cross-sectional study was carried out in north-western Italy. A total of 2063 samples from 83 commercial and 31 backyard poultry farms were analysed using real-time PCRs for Chlamydiaceae screening and species typing. Chlamydiaceae were detected in 23 farms, with a herd prevalence of 20.2% (95%CI: 13.2-28.7), higher in backyard farms (38.7%; 95%CI: 21.8-57.8) compared to commercial ones (13.3%; 95%CI: 6.8-22.5). C. gallinacea was found in 18 chicken farms, both commercial and backyard, and C. psittaci only in 3 backyard farms. Exposure to wild birds and factors related to biosecurity resulted the main risk factors associated with Chlamydia positivity. Out of the 113 sputum samples collected from farmers, 16 tested positive to Chlamydiaceae, with a prevalence of 14.2% (95%CI: 8, 3-22). To the best of our knowledge, for the first time at international level, C. gallinacea was detected in humans with farmer positivity associated with farm infectious status, suggesting a bird-to-human transmission.

Polymorphic Membrane Protein 17G of Chlamydia psittaci Mediated the Binding and Invasion of Bacteria to Host Cells by Interacting and Activating EGFR of the Host

Chlamydia psittaci (C. psittaci) is an obligate intracellular, gram-negative bacterium, and mainly causes systemic disease in psittacine birds, domestic poultry, and wild fowl. The pathogen is threating to human beings due to closely contacted to employees in poultry industry. The polymorphic membrane proteins (Pmps) enriched in C. psittaci includes six subtypes (A, B/C, D, E/F, G/I and H). Compared to that of the 1 pmpG gene in Chlamydia trachomatis (C. trachomatis), the diverse pmpG gene-coding proteins of C. psittaci remain elusive. In the present study, polymorphic membrane protein 17G (Pmp17G) of C. psittaci mediated adhesion to different host cells. More importantly, expression of Pmp17G in C. trachomatis upregulated infections to host cells. Afterwards, crosstalk between Pmp17G and EGFR was screened and identified by MALDI-MS and Co-IP. Subsequently, EGFR overexpression in CHO-K1 cells and EGFR knockout in HeLa 229 cells were assessed to determine whether Pmp17G directly correlated with EGFR during Chlamydial adhesion. Finally, the EGFR phosphorylation was recognized by Grb2, triggering chlamydial invasion. Based on above evidence, Pmp17G possesses adhesive property that serves as an adhesin and activate intracellular bacterial internalization by recognizing EGFR during C. psittaci infection

A multiplex real-time PCR assay for differential identification of avian Chlamydia

Avian chlamydiosis is an acute or chronic disease of birds after infection by Chlamydia. Although Chlamydia psittaci is the primary agent of the disease, two additional species, Chlamydia avium and Chlamydia gallinacea, have also been recognized as potential disease agents. Therefore, the diagnosis of avian chlamydiosis requires differential identification of these avian Chlamydia species. The objective of the present study was to develop a multiplex real-time polymerase chain reaction (PCR) assay to rapidly differentiate between these three species of avian Chlamydia (C. psittaci, C. avium, and C. gallinacea) as well as the genus Chlamydia. Specific genetic regions of the three species were identified by comparative analysis of their genome sequences. Also, the genus-specific region was selected based on 23S rRNA sequences. PCR primers and probes specific to the genus and each species were designed and integrated in the multiplex real-time PCR assay. The assay was highly efficient (94.8-100.7%). It detected less than 10 copies of each target sequence of the genus and each species. Twenty-five Chlamydia control and field DNA samples were differentially identified while 20 other bacterial strains comprising 10 bacterial genera were negative in the assay. This assay allows rapid, sensitive, and specific detection of the genus and the three species of avian Chlamydia in a single protocol that is suitable for routine diagnostic purposes in avian diagnostic laboratories.

Experimental inoculation of chicken broilers with C. gallinacea strain 15-56/1

Chlamydia gallinacea is one of the new Chlamydia species, encountered predominantly in birds and occasionally in cattle, and its dissemination, pathogenicity and zoonotic potential have not yet been fully elucidated. Until now, no case of clinical infection has been described in poultry, but the number of studies is limited. This study was conducted to evaluate the course of infection and the impact on production parameters in chicken broilers inoculated with the strain 15-56/1 isolated from a Polish flock. The presence of C. gallinacea was confirmed in oropharyngeal and cloacal swabs by real-time PCR from the fifth day post inoculation (dpi). Pathogen DNA was also detected in many internal organs of inoculated chickens. All infected animals remained asymptomatic during the entire experimental period, although statistical analyses showed that broilers in the experimental group exhibited significantly lower body weight gains and feed conversion ratios than animals in the control group. These data indicate that subclinical C. gallinacea infection in broilers may lead to financial losses for poultry farmers.

Undiagnosed Cases of Human Pneumonia Following Exposure to Chlamydia psittaci from an Infected Rosella Parrot

This report describes two cases of occupational exposure to Chlamydia psittaci following dissection of an infected Rosella (Platycercus elegans). The C. psittaci infections (with one of them resulting in diagnosed pneumonia and hospitalisation) were undiagnosed during routine medical investigations but later established due to epidemiological and clinical evidence, and molecular testing of the archived Rosella’ specimens. This case report stresses the importance of correct application and interpretation of diagnostic tests and the need to raise awareness about this zoonotic pathogen among medical practitioners and people exposed to potential animal carriers. Our findings suggest other infected individuals might be misdiagnosed and that C. psittaci (psittacosis) is likely to be underreported in Australia. This case highlights the need to operationalise the One Health concept. We call for improved communication between human and animal health service providers to allow accurate and rapid diagnosis of this zoonotic disease and raised awareness among medical practitioners. Further targeted surveys of wild birds (and other animals) should be conducted to improve assessment of risks to the general population and people working with or exposed to wild birds.

A comprehensive review on avian chlamydiosis: a neglected zoonotic disease

Avian chlamydiosis is one of the important neglected diseases with critical zoonotic potential. Chlamydia psittaci, the causative agent, affects most categories of birds, livestock, companion animals, and humans. It has many obscured characters and epidemiological dimensions, which makes it unique among other bacterial agents. Recent reports on transmission from equine to humans alarmed the public health authorities, and it necessitates the importance of routine screening of this infectious disease. High prevalence of spill-over infection in equines was associated with reproductive losses. Newer avian chlamydial species are being reported in the recent years. It is a potential biological warfare agent and the disease is an occupational hazard mainly to custom officers handling exotic birds. Prevalence of the disease in wild birds, pet birds, and poultry causes economic losses to the poultry industry and the pet bird trade. Interestingly, there are speculations on the ‘legal’ and ‘illegal’ bird trade that may be the global source of some of the most virulent strains of this pathogen. The mortality rate generally ranges from 5 to 40% in untreated cases, but it can sometimes be higher in co-infection. The intracellular lifestyle of this pathogen makes the diagnosis more complicated and there is also lack of accurate diagnostics. Resistance to antibiotics is reported only in some pathogens of the Chlamydiaceae family, but routine screening may assess the actual situation in all pathogens. Due to the diverse nature of the pathogen, the organism necessitates the One Health partnerships to have complete understanding. The present review focuses on the zoonotic aspects of avian chlamydiosis with its new insights into the pathogenesis, transmission, treatment, prevention, and control strategies. The review also briefs on the basic understandings and complex epidemiology of avian chlamydiosis, highlighting the need for research on emerging one health perspectives.

Metagenomic next-generation sequencing in the family outbreak of psittacosis: the first reported family outbreak of psittacosis in China under COVID-19

Chlamydia psittaci infection in humans, also known as psittacosis, is usually believed to be an uncommon disease which mainly presents as community-acquired pneumonia (CAP). It is usually sporadic, but outbreaks of infection may occasionally occur. In outbreaks, diagnosis and investigations were usually hampered by the non-specificity of laboratory testing methods to identify C. psittaci. In this study, we use metagenomic next-generation sequencing (mNGS) in the diagnosis of a family outbreak of psittacosis under COVID-19. Three members of an extended family of 6 persons developed psittacosis with pneumonia and hepatic involvement with common symptoms of fever and weakness. Two newly purchased pet parrots, which had died successively, were probably the primary source of infection. Imagings show lung consolidations and infiltrates, which are difficult to be differentiated from CAP caused by other common pathogens. mNGS rapidly identified the infecting agent as C. psittaci within 48 h. The results of this work suggest that there are not characteristic clinical manifestations and imagings of psittacosis pneumonia which can differentiate from CAP caused by other pathogens. The use of mNGS can improve accuracy and reduce the delay in the diagnosis of psittacosis especially during the outbreak, which can shorten the course of the disease control. Family outbreak under COVID-19 may be related to the familial aggregation due to the epidemic. To our knowledge, this is the first reported family outbreak of psittacosis in China, and the first reported psittacosis outbreak identified by the method of mNGS in the world.

Clinical Analysis of Metagenomic Next-Generation Sequencing Confirmed Chlamydia psittaci Pneumonia: A Case Series and Literature Review

Introduction

Chlamydia psittaci infection is a zoonotic infectious disease, which mainly inhaled through the lungs when exposed to the secretions of poultry that carry pathogenic bacteria. The traditional respiratory specimens or serological antibody testing is slow, and the false-negative rate is high. Metagenomic next-generation sequencing (mNGS) gives a promising rapid diagnosis tool.

Methods

We retrospectively summarized the clinical characteristics of five C. psittaci pneumonia patients diagnosed by mNGS, conducted a literature review summarizing the clinical characteristics of patients with C. psittaci pneumonia reported since 2010.

Results

Five C. psittaci pneumonia patients confirmed by mNGS aged from 36 to 66 years with three males. About 60% of patients had a history of contact with avian or poultry. All patients had a high fever over 38.5 °C, cough, hypodynamia, hypoxemia, and dyspnea on admission. Two patients had invasive ventilator support and extracorporeal membrane oxygenation support. Inflammatory index levels on admission and follow-up were all higher than normal values. Doxycycline or moxifloxacin and their combination therapy were used in patients. Four patients improved and were discharged, and one patient died due to multiple organ failures and disseminated intravascular coagulation. We summarized 19 articles including 69 C. psittaci pneumonia patients and patients in 11 publications were identified by mNGS, and most patients are treated with tetracycline and quinolone with good outcomes.

Conclusion

mNGS is a promising rapid diagnosis tool, which may increase the detection rate and shorten the diagnosis time of C. psittaci pneumonia. Further case-control studies are needed to confirm.

Chlamydiae - What's New?

This paper provides an overview of the current knowledge of chlamydiae. These intracellular microorganisms belonging to the Chlamydiaceae family are widely distributed throughout the world. Constant development of culture-independent approaches for characterisation of microbial genomes enables new discoveries in the field of Chlamydia. The number of new taxa is continuously increasing as well as the range of hosts. New species and genotypes are constantly being discovered, particularly new avian and reptilian agents, which are discussed in this article. Interestingly, wild animals are the main hosts for new Chlamydia species including different species of bird, turtle and snake. The availability of next-generation sequencing opens up a new prospect for research and leads to deeper knowledge of these interesting microorganisms about which much is still to discover.

Psittacosis Outbreak among Workers at Chicken Slaughter Plants, Virginia and Georgia, USA, 2018

During August–October, 2018, an outbreak of severe respiratory illness was reported among poultry slaughter plant workers in Virginia and Georgia, USA. A multiorganizational team investigated the cause and extent of illness, determined that the illness was psittacosis, and evaluated and recommended controls for health hazards in the workplace to prevent additional cases.

Animal sources for zoonotic transmission of psittacosis: a systematic review

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.

Cross-sectional study on Chlamydiaceae prevalence and associated risk factors on commercial and backyard poultry farms in Mexico

Chlamydiaceae infections in poultry are mainly due to Chlamydia psittaci and Chlamydia gallinacea. While C. psittaci has long been known to affect birds and to have zoonotic potential, C. gallinacea is a newly described species that has been found to be widespread in chickens. As no data were available regarding the presence of Chlamydiaceae in Mexican poultry, a cross-sectional survey to detect the presence of Chlamydiaceae on commercial and backyard farms was carried out in eight federal states of Mexico with a high poultry density. Individual cloacal swabs were collected on 14 large-scale commercial poultry farms with controlled environment houses, 23 large-scale commercial poultry farms with open-sided houses, and 16 backyard farms. Samples were tested using a specific Chlamydiaceae real-time PCR technique. Chlamydial species were subsequently identified by a species-specific real-time PCR method. Information on potential risk factors was collected through a questionnaire. Logistic regression was performed to identify risk factors associated with Chlamydiaceae-positive results at the farm level on commercial farms. For backyard farms, a mixed-effect logistic regression model was used to consider information collected either at the animal or at the farm level. Overall, 7.1 % (n = 1/14) of controlled environment commercial farms, 26.1 % (n = 6/23) of open-sided commercial farms, and 75.0 % (n = 12/16) of backyard farms were Chlamydiaceae-positive. Apparent prevalence increased inversely to the level of confinement (controlled environment vs open-sided poultry houses vs backyards). Chlamydia gallinacea was the only chlamydial species detected. On commercial farms, egg-laying hen flocks had 6.7 times higher odds of being Chlamydiaceae-infected than broilers flocks (OR = 6.7, 95 % CI: 1.1-44.3, p = 0.04). On backyard farms, two variables were significantly associated with Chlamydiaceae infection: the lack of antibiotic use (OR = 8.4, 95 % CI: 1.84-38.49, p = 0.006), and an impaired health status (OR=8.8, 95 % CI: 1.9-38.9, p = 0.004). Further studies should be carried out to investigate the impact of C. gallinacea infection on egg quality and production performance in egg-laying hen flocks.

Human psittacosis: a review with emphasis on surveillance in Belgium

Chlamydia psittaci causes psittacosis in humans, mainly in persons in contact with birds in either the setting of occupational or companion bird exposure. Infection is associated with a range of clinical manifestations from asymptomatic infection to severe atypical pneumonia and systemic disease. This paper reviews new knowledge on psittacosis, its legal and regulatory aspects and presents epidemiological data on psittacosis in Belgium. In Belgium, the number of reported positive laboratory results increased slowly since 2010, and in 2017, the number almost doubled compared to the two previous years. The number of psittacosis cases in Belgium, as in other countries, is probably highly underestimated, because of underdiagnoses and underreporting. Over the 3-year period, the mandatory notification system registered 24% only of all reported positive laboratory result. Therefore, increased awareness among general and occupational physicians, clinicians and the public is needed. Policies aimed at reducing psittacosis disease burden are justified, nevertheless national health authorities should provide more legal and financial support to implement more adequate C. psittaci diagnostic tools.

Challenges in using serological methods to explore historical transmission risk of Chlamydia psittaci in a workforce with high exposure to equine chlamydiosis

Introduction

This report describes the challenges encountered in using serological methods to study the historical transmission risk of C. psittaci from horses to humans.

Methods

In 2017, serology and risk factor questionnaire data from a group of individuals, whose occupations involved close contact with horses, were collected to assess the seroprevalence of antibodies to C. psittaci and identify risk factors associated with previous exposure.

Results

147 participants were enrolled in the study, provided blood samples, and completed a questionnaire. On ELISA testing, antibodies to the Chlamydia genus were detected in samples from 17 participants but further specific species-specific MIF testing did not detect C. psittaci-specific antibodies in any of these samples.

Conclusion

No serological evidence of past C. psittaci transmission from horses to humans was found in this study cohort. There are major challenges in using serological methods to determine the prevalence of C. psittaci exposure.

Chlamydiaceae: Diseases in Primary Hosts and Zoonosis

Bacteria of the Chlamydiaceae family are a type of Gram-negative microorganism typified by their obligate intracellular lifestyle. The majority of the members in the Chlamydiaceae family are known pathogenic organisms that primarily infect the host mucosal surfaces in both humans and animals. For instance, Chlamydia trachomatis is a well-known etiological agent for ocular and genital sexually transmitted diseases, while C. pneumoniae has been implicated in community-acquired pneumonia in humans. Other chlamydial species such as C. abortus, C. caviae, C. felis, C. muridarum, C. pecorum, and C. psittaci are important pathogens that are associated with high morbidities in animals. Importantly, some of these animal pathogens have been recognized as zoonotic agents that pose a significant infectious threat to human health through cross-over transmission. The current review provides a succinct recapitulation of the characteristics as well as transmission for the previously established members of the Chlamydiaceae family and a number of other recently described chlamydial organisms.

Risk factors associated with Chlamydia psittaci infections in psittacine birds and bird handlers

AIMS

The aim of this study was to determine the prevalence and potential risk factors associated with Chlamydia psittaci infections in psittacine birds and bird handlers in Egypt.

METHODS AND RESULTS

A total of 190 swabs were collected from psittacine birds (n = 120) and bird handlers (n = 70) and were tested by polymerase chain reaction to detect the C. psittaci ompA gene. Chlamydia psittaci DNA was detected in 63 (52·5%) of 120 samples collected from psittacine birds. The occurrence of C. psittaci infections was high in Cockatiel birds (60%), followed by Fischer's lovebird (51%) and Rosy-faced lovebird (47·5%). Bird age, location (pet markets and households), housing (caged and aviary), and sampling season were considered significant risk factors for C. psittaci infections in psittacine birds. Of the 70 sputum swabs collected from bird handlers, only 4 (6%) were positive for C. psittaci. Positive cases were closely associated with older persons (≥30 years) who had respiratory signs and handled birds in pet markets. Further, wearing protective gloves and washing hands when handling psittacine birds decreased the frequency of C. psittaci infections in bird handlers.

CONCLUSIONS

The prevalence of C. psittaci infections in psittacine birds in Egypt is high, which has a potential threat to human health in this area. Thus, dissemination of effective prevention and control measures is essential to prevent the spread of C. psittaci among psittacine birds, as well as among humans in contact with birds.

SIGNIFICANCE AND IMPACT OF THE STUDY

Results from this study highlighted the risk factors associated with C. psittaci infections in psittacine birds and bird handlers in Egypt and will aid in developing prevention and control measures to reduce the risk of C. psittaci infection.

Laboratory methods for case finding in human psittacosis outbreaks: a systematic review

Background

Psittacosis outbreak investigations require rapid identification of cases in order to trace possible sources and perform public health risk assessments. In recent outbreaks in the Netherlands, such investigations were hampered by the non-specificity of laboratory testing methods to identify human Chlamydia psittaci infections.

Method

A systematic search of PubMed and Scopus databases of literature published between 01 January, 1986 and 03 July, 2017 was done to find best practices of laboratory-testing methods used in psittacosis outbreaks of two or more human cases. Reference lists of included articles were hand searched to identify additional articles.

Results

Thirty-seven eligible articles were identified, describing 44 human psittacosis outbreaks in 12 countries. Laboratory tests performed were PCR (with various targets), serologic tests (complement binding reactions, ELISA’s, immunofluorescence tests and immuno-peroxidase tests) and culture, in various combinations. The literature provided no ‘gold standard’ laboratory testing strategy to identify recent human C. psittaci infections. In most psittacosis outbreaks, for a considerable number of cases (or tested individuals in an exposed cohort), C. psittaci infection could not be confirmed, nor excluded as causative pathogen. None of the testing strategies was found to be suitable for (nearly) full case finding.

Conclusion

PCR enables rapid identification of human psittacosis patients and helps source finding by genotyping but has the disadvantage that sensitivity is high only in the acute phase. In outbreak situations, there is often a time delay and therefore, there is a need for new serologic testing methods next to PCR, with good specificity and sensitivity. Moreover, serum is easier to collect than the preferred diagnostic materials for PCR. A serologic test that can reliably confirm infection status without the necessity of convalescent serum sampling would enhance case finding, source tracing, identification of risk factors and assessment of burden of disease in various settings.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3317-0) contains supplementary material, which is available to authorized users.

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

Psittacosis is a zoonotic disease transmitted by birds. In Sweden, where psittacosis is notifiable, an average of eight cases per year were reported between 2002 and 2012. In 2013, an unusual increase in cases in southern Sweden was associated with exposure to wild birds. To further explore specific risk factors connected to wild birds and identify other risk factors for sporadic psittacosis, we conducted a case-control study including all domestically acquired psittacosis cases reported between December 2014 and April 2016 in Sweden. Cases were age-, sex- and geo-matched to controls randomly selected from a population register. Cases and controls completed a questionnaire investigating detailed exposures to wild and domestic birds. We compared cases to controls, calculating adjusted matched odds ratios (amOR) using conditional logistic regression. Thirty-one cases were notified: all cases lived in southern Sweden and 26 were ill during winter season. Two risk factors were independently associated with psittacosis infection: cleaning a wild bird feeder (amOR = 18.95; 95% CI: 2.11-170.03) and owning domestic birds (amOR = 5.55, 95% CI: 1.16-26.61). Our results suggest that exposure to bird faeces, for example when cleaning a wild bird feeder, was the main route of transmission. Following this study, the Public Health Agency of Sweden published recommendations on good practices when cleaning surfaces contaminated with bird faeces and recommended use of bird feeders with a design limiting faeces accumulation.

Detection of Chlamydiaceae and Chlamydia-like organisms on the ocular surface of children and adults from a trachoma-endemic region

Trachoma, the leading infectious cause of blindness, is caused by Chlamydia trachomatis (Ct), a bacterium of the phylum Chlamydiae. Recent investigations revealed the existence of additional families within the phylum Chlamydiae, also termed Chlamydia-like organisms (CLOs). In this study, the frequency of Ct and CLOs was examined in the eyes of healthy Sudanese (control) participants and those with trachoma (case). We tested 96 children (54 cases and 42 controls) and 93 adults (51 cases and 42 controls) using broad-range Chlamydiae and Ct-specific (omcB) real-time PCR. Samples positive by broad-range Chlamydiae testing were subjected to DNA sequencing. Overall Chlamydiae prevalence was 36%. Sequences corresponded to unclassified and classified Chlamydiae. Ct infection rate was significantly higher in children (31.5%) compared to adults (0%) with trachoma (p < 0.0001). In general, 21.5% of adults and 4.2% of children tested positive for CLOs (p = 0.0003). Our findings are consistent with previous investigations describing the central role of Ct in trachoma among children. This is the first study examining human eyes for the presence of CLOs. We found an age-dependent distribution of CLO DNA in human eyes with significantly higher positivity in adults. Further studies are needed to understand the impact of CLOs in trachoma pathogenicity and/or protection.

A Psittacosis Outbreak among English Office Workers with Little or No Contact with Birds, August 2015

Introduction

On 14th August 2015 an office manager informed Public Health England of five employees known to have been diagnosed with pneumonia over the previous three weeks. We investigated to establish whether an outbreak occurred and to identify and control the source of infection.

Methods

We undertook case finding for self-reported pneumonia cases at local businesses (July-August 2015). Clinical samples from a hospitalised case were tested for common respiratory pathogens, but returned negative results. Further testing confirmed Chlamydia psittaci infection in this case (serology and PCR).  We subsequently undertook C. psittaci testing for all cases, redefining them as confirmed (C. psittaci PCR or high antibody titre via serology) or probable (inconclusive C. psittaci serology). Twenty-eight day exposure histories informed descriptive epidemiological analysis. We conducted an environmental investigation at the office to identify potential sources of exposure.

Results

We identified six office workers with pneumonia; four met case definitions (three confirmed, one probable) with symptom onset between 29th July and 4th August 2015. Workplace was the only epidemiological link and only one case reported limited, indirect bird contact. Environmental investigations identified pigeons roosting near the office which were being fed by workers (none cases).

Discussion

This was a probable outbreak of psittacosis with no direct bird-to-human contact reported. Cases recovered after receiving appropriate antibiotics. Feeding of pigeons was stopped. A deep clean of office ventilation systems was conducted and workers were advised to avoid bird contact.  We hypothesised that indirect environmental exposure to infected pigeons was to the source of this outbreak. This work provides evidence that health professionals should consider psittacosis in the differential diagnosis of cases of severe or atypical respiratory illness even without overt bird contact.

Oral Chlamydia vaccination induces transmucosal protection in the airway

Although Chlamydia has been frequently detected in the gastrointestinal tracts of both humans and animals, it is not associated with any gastrointestinal pathology. We have recently shown that gastrointestinal Chlamydiamuridarum is not only non-pathogenic but also induces protective immunity in the genital tract. We now report that the transmucosal immunity induced by a single oral immunization with C.muridarum protected the mouse airway from a subsequent challenge infection. The oral immunization significantly reduced chlamydial burden in the airway as early as day 3 after intranasal challenge. As a result, the airway chlamydial spreading to extra-airway tissues was completely prevented on day 3 and significantly reduced on day 9. The immunized mice were protected from any significant systemic toxicity caused by the intranasal challenge since there was no significant bodyweight drop in the immunized mice. This robust protection correlated well with Chlamydia-specific antibodies that recognize chlamydial organism surface antigens and T cell responses that are dominated with a Th1 phenotype. The immunized mice developed high ratios of IgG2b/c over IgG1 levels and IFNγ-producing over IL-5- or IL-13-producing lymphocytes. Thus, we have demonstrated that oral vaccination with C. muridarum can induce Th1-dominant transmucosal immunity in the airway. Together with previous studies, we propose that non-pathogenic colonization of Chlamydia in the gastrointestinal tract be explored as an oral delivery system for inducing protection against infections and pathologies in extra-gastrointestinal tissues.

Chlamydiosis in Backyard Chickens (Gallus gallus) in Italy

Until recently, Chlamydia psittaci was considered to be the only etiological agent of avian chlamydiosis, but two new avian species, Chlamydia gallinacea and Chlamydia avium, have recently been described in poultry and pigeons or psittacine birds, respectively. The aim of this study was to explore the occurrence of C. psittaci and C. gallinacea in backyard chickens in Italy. Cloacal swabs were taken from 160 asymptomatic chickens reared in 16 backyard farms. Samples were tested for C. psittaci and C. gallinacea by specific real-time polymerase chain reaction assays, with 24 (15%) of the 160 chickens resulting positive for C. gallinacea. To attempt chlamydial isolation, new samples were obtained from two farms harboring a high prevalence (60% and 70%, respectively) of C. gallinacea-positive chickens. In total, eight C. gallinacea and one C. psittaci isolates were successfully recovered from 13 chickens. C. gallinacea was confirmed to be the endemic chlamydial species in chickens, with a high ompA intraspecies diversity. The presence of viable C. psittaci and C. gallinacea demonstrated by isolation from chickens in backyard farms poses a potential public health problem.

Molecular evidence to suggest pigeon-type Chlamydia psittaci in association with an equine foal loss

Chlamydia psittaci is an important avian pathogen with spillover from infected wild and domesticated birds also posing a risk to human health. We recently reported a case of C. psittaci equine placentitis associated with further spillover to humans. Molecular typing of this case revealed it belonged to the 6BC clade of C. psittaci, a globally distributed highly virulent set of strains, typically linked to infection spillover from parrots. Equine chlamydiosis associated with C. psittaci infection has previously been reported elsewhere in countries where parrots are not endemic, however, raising questions over the identity of infecting C. psittaci strains and the potential infection reservoirs. In this study, we describe the detection and molecular characterization of C. psittaci in a case of equine abortion in southern Queensland. Equine placenta and fresh liver and lung tissue from the necropsied foetus were positive by C. psittaci-specific qPCR. Chlamydia psittaci-specific multilocus sequence typing and ompA genotyping were used to further characterize the detected equine strains and an additional strain obtained from a dove from a different geographic region presenting with psittacosis. Molecular typing of this case revealed that the infecting equine strains were closely related to the C0sittaci detected in dove, all belonging to an evolutionary lineage of C. psittaci strains typically associated with infections of pigeons globally. This finding suggests a broader diversity of C. psittaci strains may be detected in horses and in association with reproductive loss, highlighting the need for an expansion of surveillance studies globally to understand the epidemiology of equine chlamydiosis and the associated zoonotic risk.

A cross sectional study on Dutch layer farms to investigate the prevalence and potential risk factors for different Chlamydia species

In poultry several Chlamydia species have been detected, but Chlamydia psittaci and Chlamydia gallinacea appear to be most prevalent and important. Chlamydia psittaci is a well-known zoonosis and is considered to be a pathogen of poultry. Chlamydia gallinacea has been described more recently. Its avian pathogenicity and zoonotic potential have to be further elucidated. Within the Netherlands no data were available on the presence of Chlamydia on poultry farms. As part of a surveillance programme for zoonotic pathogens in farm animals, we investigated pooled faecal samples from 151 randomly selected layer farms. On a voluntary base, 69 farmers, family members or farm workers from these 151 farms submitted a throat swab. All samples were tested with a generic 23S Chlamydiaceae PCR followed by a species specific PCR for C. avium, C. gallinacea and C. psittaci. C. avium and psittaci DNA was not detected at any of the farms. At 71 farms the positive result could be confirmed as C. gallinacea. Variables significantly associated with the presence of C. gallinacea in a final multivariable model were ‘age of hens,’ ‘use of bedding material’ and ‘the presence of horses.’ The presence of C. gallinacea was associated with neither clinical signs, varying from respiratory symptoms, nasal and ocular discharges to diarrhoea, nor with a higher mortality rate the day before the visit. All throat swabs from farmers, family members or farm workers tested negative for Chlamydia DNA, giving no further indication for possible bird-to-human (or human-to-bird) transmission.

Poultry in Poland as Chlamydiaceae Carrier

Introduction

The study was conducted to investigate the prevalence and genetic diversity of Chlamydia spp. in poultry in Poland and estimate possible transmission to humans.

Material and Methods

Molecular diagnostic methods followed by sequencing and strain isolation were used on cloacal/faecal swabs collected from 182 apparently healthy poultry flocks including chickens, turkeys, ducks, and geese. Serum samples obtained from people exposed (study group) and non-exposed (control group) to birds were tested by complement fixation test to acquire data on Chlamydia spp. antibody level.

Results

Overall, 15.9% of the tested flocks were Chlamydiaceae-positive and three Chlamydia spp. were identified. Predominant chlamydial agent found was C. gallinacea occurring in 65.5% of all positive poultry flocks and in 73.0% of positive chicken flocks. The sequences from four chicken flocks were assigned to C. abortus, whereas C. psittaci was confirmed in one duck and one goose flock. The analysis of ompA variable domains revealed at least nine genetic variants of C. gallinacea. Chlamydial antibodies were detected in 19.2% of human serum samples in the study group in comparison with 10.8% in the controls.

Conclusion

The obtained results confirm that chlamydiae are common among chicken flocks in Poland with C. gallinacea as a dominant species. Moreover, the presence of C. abortus in chickens is reported here for the first time. Further investigation should focus on possible zoonotic transmission of C. gallinacea and C. abortus as well as potential pathogenic effects on birds’ health and poultry production.

From genomes to genotypes: molecular epidemiological analysis of Chlamydia gallinacea reveals a high level of genetic diversity for this newly emerging chlamydial pathogen

BACKGROUND

Chlamydia (C.) gallinacea is a recently identified bacterium that mainly infects domestic chickens. Demonstration of C. gallinacea in human atypical pneumonia suggests its zoonotic potential. Its prevalence in chickens exceeds that of C. psittaci, but genetic and genomic research on C. gallinacea is still at the beginning. In this study, we conducted whole-genome sequencing of C. gallinacea strain JX-1 isolated from an asymptomatic chicken, and comparative genomic analysis between C. gallinacea strains and related chlamydial species.

RESULTS

The genome of C. gallinacea JX-1 was sequenced by single-molecule, real-time technology and is comprised of a 1,059,522-bp circular chromosome with an overall G + C content of 37.93% and sequence similarity of 99.4% to type strain 08-1274/3. In addition, a plasmid designated pJX-1, almost identical to p1274 of the type strain, except for two point mutations, was only found in field strains from chicken, but not in other hosts. In contrast to chlamydial species with notably variable polymorphic membrane protein (pmp) genes and plasticity zone (PZ), these regions were conserved in both C. gallinacea strains. There were 15 predicted pmp genes, but only B, A, E1, H, G1 and G2 were apparently intact in both strains. In comparison to chlamydial species where the PZ may be up to 50 kbp, C. gallinacea strains displayed gene content reduction in the PZ (14 kbp), with strain JX-1 having a premature STOP codon in the cytotoxin (tox) gene, while tox gene is intact in the type strain. In multilocus sequence typing (MLST), 15 C. gallinacea STs were identified among 25 strains based on cognate MLST allelic profiles of the concatenated sequences. The type strain and all Chinese strains belong to two distinct phylogenetic clades. Clade of the Chinese strains separated into 14 genetically distinct lineages, thus revealing considerable genetic diversity of C. gallinacea strains in China.

CONCLUSIONS

In this first detailed comparative genomic analysis of C. gallinacea, we have provided evidence for substantial genetic diversity among C. gallinacea strains. How these genetic polymorphisms affect C. gallinacea biology and pathogenicity should be addressed in future studies that focus on phylogenetics and host adaption of this enigmatic bacterial agent.

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

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.

Development and evaluation of rapid novel isothermal amplification assays for important veterinary pathogens: Chlamydia psittaci and Chlamydia pecorum

Background

Chlamydia psittaci and Chlamydia pecorum are important veterinary pathogens, with the former also being responsible for zoonoses, and the latter adversely affecting koala populations in Australia and livestock globally. The rapid detection of these organisms is still challenging, particularly at the point-of-care (POC). In the present study, we developed and evaluated rapid, sensitive and robust C. psittaci-specific and C. pecorum-specific Loop Mediated Isothermal Amplification (LAMP) assays for detection of these pathogens.

Methods and Materials

The LAMP assays, performed in a Genie III real-time fluorometer, targeted a 263 bp region of the C. psittaci-specific Cps_0607 gene or a 209 bp region of a C. pecorum-specific conserved gene CpecG_0573, and were evaluated using a range of samples previously screened using species-specific quantitative PCRs (qPCRs). Species-specificity for C. psittaci and C. pecorum LAMP targets was tested against DNA samples from related chlamydial species and a range of other bacteria. In order to evaluate pathogen detection in clinical samples, C. psittaci LAMP was evaluated using a total of 26 DNA extracts from clinical samples from equine and avian hosts, while for C. pecorum LAMP, we tested a total of 63 DNA extracts from clinical samples from koala, sheep and cattle hosts. A subset of 36 C. pecorum samples was also tested in a thermal cycler (instead of a real-time fluorometer) using newly developed LAMP and results were determined as an end point detection. We also evaluated rapid swab processing (without DNA extraction) to assess the robustness of these assays.

Results

Both LAMP assays were demonstrated to species-specific, highly reproducible and to be able to detect as little as 10 genome copy number/reaction, with a mean amplification time of 14 and 24 min for C. psittaci and C. pecorum, respectively. When testing clinical samples, the overall congruence between the newly developed LAMP assays and qPCR was 92.3% for C. psittaci (91.7% sensitivity and 92.9% specificity); and 84.1% for C. pecorum (90.6% sensitivity and 77.4% specificity). For a subset of 36 C. pecorum samples tested in a thermal cycler using newly developed LAMP, we observed 34/36 (94.4%) samples result being congruent between LAMP performed in fluorometer and in thermal cycler. Rapid swab processing method evaluated in this study also allows for chlamydial DNA detection using LAMP.

Discussion

In this study, we describe the development of novel, rapid and robust C. psittaci-specific and C. pecorum-specific LAMP assays that are able to detect these bacteria in clinical samples in either the laboratory or POC settings. With further development and a focus on the preparation of these assays at the POC, it is anticipated that both tests may fill an important niche in the repertoire of ancillary diagnostic tools available to clinicians.

Review of Nonfoodborne Zoonotic and Potentially Zoonotic Poultry Diseases

Emerging and re-emerging diseases are continuously diagnosed in poultry species. A few of these diseases are known to cross the species barrier, thus posing a public health risk and an economic burden. We identified and synthesized global evidence for poultry nonfoodborne zoonoses to better understand these diseases in people who were exposed to different poultry-related characteristics (e.g., occupational or nonoccupational, operational types, poultry species, outbreak conditions, health status of flocks). This review builds on current knowledge on poultry zoonoses/potentially zoonotic agents transmitted via the nonfoodborne route. It also identifies research gaps and potential intervention points within the poultry industry to reduce zoonotic transmission by using various knowledge synthesis tools such as systematic review (SR) and qualitative (descriptive) and quantitative synthesis methods (i.e., meta-analysis). Overall, 1663 abstracts were screened and 156 relevant articles were selected for further review. Full articles (in English) were retrieved and critically appraised using routine SR methods. In total, eight known zoonotic diseases were reviewed: avian influenza (AI) virus (n = 85 articles), Newcastle disease virus (n = 8), West Nile virus (WNV, n = 2), avian Chlamydia (n = 24), Erysipelothrix rhusiopathiae (n = 3), methicillin-resistant Staphylococcus aureus (MRSA, n = 15), Ornithonyssus sylvarium (n = 4), and Microsporum gallinae (n = 3). In addition, articles on other viral poultry pathogens (n = 5) and poultry respiratory allergens derived from mites and fungi (n = 7) were reviewed. The level of investigations (e.g., exposure history, risk factor, clinical disease in epidemiologically linked poultry, molecular studies) to establish zoonotic linkages varied across disease agents and across studies. Based on the multiple outcome measures captured in this review, AI virus seems to be the poultry zoonotic pathogen that may have considerable and significant public health consequences; however, epidemiologic reports have only documented severe human cases clustered in Asia and not in North America. In contrast, avian Chlamydia and MRSA reports clustered mainly in Europe and less so in North America and other regions. Knowledge gaps in other zoonoses or other agents were identified, including potential direct (i.e., nonmosquito-borne) transmission of WNV from flocks to poultry workers, the public health and clinical significance of poultry-derived (livestock-associated) MRSA, the zoonotic significance of other viruses, and the role of poultry allergens in the pathophysiology of respiratory diseases of poultry workers. Across all pathogens reviewed, the use of personal protective equipment was commonly cited as the most important preventive measure to reduce the zoonotic spread of these diseases and the use of biosecurity measures to reduce horizontal transmission in flock populations. The studies also emphasized the need for flock monitoring and an integrated approach to prevention (i.e., veterinary-public health coordination with regard to diagnosis, and knowledge translation and education in the general population) to reduce zoonotic transmission.

First Identification of Chlamydia psittaci in the Acute Illness and Death of Endemic and Endangered Psittacine Birds in Mexico

A mortality episode of endemic and endangered psittacine birds from the genera Ara and Amazona occurred during January 2015. The birds were housed in a management unit for wildlife conservation that receives wild-caught birds from illegal trade. In total, 11 (57%) adult birds of different origins that shared these accommodations died. Only four of them were sent for diagnosis. The main lesions found at necropsy were consistent with those described previously for avian chlamydiosis; the presence of Chlamydiaceae was confirmed through immunofluorescence and amplification with further sequencing of the 16S ribosomal RNA gene by using hepatic tissue. Due to the lack of specific diagnostic tools on primary psittacine diseases, the pathogenic effects of systemic, respiratory, or enteric infections with high mortality rates remain unknown in Mexico. In this study, specific molecular identification of avian chlamydiosis was performed using a nested PCR on liver tissues, as well as choanal and cloacal swab samples, confirming the presence of Chlamydia psittaci in all of them. In addition, it was possible to obtain the ompA gene sequence from processed clinical samples, thereby allowing us to determine that the A genotype was affecting these birds. Although this genotype is the most commonly found worldwide in psittacine birds, this case report describes the first avian chlamydiosis outbreak affecting critically endangered and endemic psittacines subjected to reintegration programs in Mexico. Consequently, this study demonstrates the necessity of more exhaustive biosecurity strategies because other pathogens may be present and should be assessed, especially in highly threatened birds, before releasing them into their habitats.

Chlamydia gallinacea: a widespread emerging Chlamydia agent with zoonotic potential in backyard poultry

Chlamydia gallinacea, a new chlamydial agent, has been reported in four European countries as well as Argentina and China. Experimentally infected chickens with C. gallinacea in previous study showed no clinical signs but had significantly reduced gains in body weight (6·5-11·4%). Slaughterhouse workers exposed to infected chickens have developed atypical pneumonia, indicating C. gallinacea is likely a zoonotic agent. In this study, FRET-PCR confirmed that C. gallinacea was present in 12·4% (66/531) of oral-pharyngeal samples from Alabama backyard poultry. Phylogenetic comparisons based on ompA variable domain showed that 16 sequenced samples represented 14 biotypes. We report for the first time the presence of C. gallinacea in North America, and this warrants further research on the organism's pathogenicity, hosts, transmission, and zoonotic potential.

Temporal and spatial analysis of psittacosis in association with poultry farming in the Netherlands, 2000-2015

Background

Human psittacosis is a highly under diagnosed zoonotic disease, commonly linked to psittacine birds. Psittacosis in birds, also known as avian chlamydiosis, is endemic in poultry, but the risk for people living close to poultry farms is unknown. Therefore, our study aimed to explore the temporal and spatial patterns of human psittacosis infections and identify possible associations with poultry farming in the Netherlands.

Methods

We analysed data on 700 human cases of psittacosis notified between 01-01-2000 and 01-09-2015. First, we studied the temporal behaviour of psittacosis notifications by applying wavelet analysis. Then, to identify possible spatial patterns, we applied spatial cluster analysis. Finally, we investigated the possible spatial association between psittacosis notifications and data on the Dutch poultry sector at municipality level using a multivariable model.

Results

We found a large spatial cluster that covered a highly poultry-dense area but additional clusters were found in areas that had a low poultry density. There were marked geographical differences in the awareness of psittacosis and the amount and the type of laboratory diagnostics used for psittacosis, making it difficult to draw conclusions about the correlation between the large cluster and poultry density. The multivariable model showed that the presence of chicken processing plants and slaughter duck farms in a municipality was associated with a higher rate of human psittacosis notifications. The significance of the associations was influenced by the inclusion or exclusion of farm density in the model.

Conclusions

Our temporal and spatial analyses showed weak associations between poultry-related variables and psittacosis notifications. Because of the low number of psittacosis notifications available for analysis, the power of our analysis was relative low. Because of the exploratory nature of this research, the associations found cannot be interpreted as evidence for airborne transmission of psittacosis from poultry to the general population. Further research is needed to determine the prevalence of C. psittaci in Dutch poultry. Also, efforts to promote PCR-based testing for C. psittaci and genotyping for source tracing are important to reduce the diagnostic deficit, and to provide better estimates of the human psittacosis burden, and the possible role of poultry.

New and emerging chlamydial infections of creatures great and small

Until recently, our knowledge of the host range and diversity of members of the Chlamydiaceae, obligate intracellular bacterial pathogens of humans and animals, was thought to be nearly complete. Aided by advances in molecular diagnostics, a new picture is emerging, however, that the host barriers may be looser than previously thought for many chlamydial species. While cross-host transmission of chlamydial species is a concern for animal health, new reports highlight an emerging zoonotic risk for several species associated with intensification of farming and the widespread popularity of companion animals. The description of an expanded cohort of new species within this family from avian and reptilian hosts has also highlighted how much we still have to learn about the biology and pathogenicity of the Chlamydiaceae as a whole. Reports emerging about these relatives of the traditional chlamydial pathogens are matched by the continued identification of novel Chlamydia-related bacteria in the phylum Chlamydiae, providing evidence that many may be pathogenic to humans or animals and pose a zoonotic or vector-borne risk. The review examines the new hosts described for well-characterized chlamydial veterinary pathogens, emerging novel chlamydial species and the potential for these to cause disease in their respective hosts.

In silico functional elucidation of uncharacterized proteins of Chlamydia abortus strain LLG

AIM

This study reports structural modeling, molecular dynamics profiling of hypothetical proteins in Chlamydia abortus genome database.

METHODOLOGY

The hypothetical protein sequences were extracted from C. abortus LLG Genome Database for functional elucidation using in silico methods.

RESULTS

Fifty-one proteins with their roles in defense, binding and transporting other biomolecules were unraveled. Forty-five proteins were found to be nonhomologous to proteins present in hosts infected by C. abortus. Of these, 31 proteins were related to virulence. The structural modeling of two proteins, first, WP_006344020.1 (phosphorylase) and second, WP_006344325.1 (chlamydial protease/proteasome-like activity factor) were accomplished. The conserved active sites necessary for the catalytic function were analyzed.

CONCLUSION

The finally concluded proteins are envisioned as possible targets for developing drugs to curtail chlamydial infections, however, and should be validated by molecular biological methods.

Chlamydial infections in wildlife-conservation threats and/or reservoirs of 'spill-over' infections?

Members of the order Chlamydiales are biphasic intracellular pathogens known to cause disease in both humans and animals. As we learn more about the genetic diversity of this group of pathogens, evidence is growing that these bacteria infect a broader range of animal hosts than previously thought. Over 400 host species are now documented globally with the majority of these being wild animals. Given the impact of chlamydial infections on humans and domesticated animals, the identification of members of the order Chlamydiales in wildlife raises significant questions over a) their impact on animal health and b) the relationships to those strains also found in humans and domestic animals. In some species such as the iconic marsupial, the koala, the conservation impact is known with chlamydial infections associated with debilitating disease, however, in general, little is known about the pathogenic potential of Chlamydiae infecting most wildlife hosts. Accumulating evidence suggests contact with wild animals is a risk factor for infections in domestic animals and/or humans. Beyond the well-recognised zoonotic pathogen, Chlamydia psittaci, a range of studies have now reported traditional pathogens in the family Chlamydiaceae such as Chlamydia pecorum, Chlamydia suis, Chlamydia pneumoniae and Chlamydia abortus in wild animals. The spectre of cross-host transmission 'spill-over' and 'spill-back' in the epidemiology of infections is of potential concern, however, comprehensive epidemiological studies are lacking for most of these. Accurate evaluation of the significance of chlamydial infections in wildlife is otherwise hampered by i) the cross-sectional nature of most impact studies, ii) a lack of standardised diagnostic approaches, iii) limited study sizes, and iv) biases associated with opportunistic sampling.

Whole-Genome Sequence of Chlamydia gallinacea Type Strain 08-1274/3

The recently introduced bacterial species Chlamydia gallinacea is known to occur in domestic poultry and other birds. Its potential as an avian pathogen and zoonotic agent is under investigation. The whole-genome sequence of its type strain, 08-1274/3, consists of a 1,059,583-bp chromosome with 914 protein-coding sequences (CDSs) and a plasmid (p1274) comprising 7,619 bp with 9 CDSs.

Emergencies and Critical Care of Commonly Kept Fowl

Fowl are birds belonging to one of the 2 biological orders, the game fowl or land fowl (Galliformes) and the waterfowl (Anseriformes). Studies of anatomic and molecular similarities suggest these two groups are close evolutionary relatives. Multiple fowl species have a long history of domestication. Fowl are considered food-producing animals in most countries and clinicians should follow legislation regarding reportable diseases and antibiotic use, even if they are pets. This article reviews aspects of emergency care for most commonly kept fowl, including triage, patient assessment, diagnostic procedures, supportive care, short-term hospitalization, and common emergency presentations.