Chlamydia psittaci in fulmars on the Faroe Islands: a causative link to South American psittacines eight decades after a severe epidemic

Molecular detection of Chlamydia psittaci in birds: a systematic review

Molecular methods are currently the most sensitive for detecting Chlamydia psittaci in birds. Most laboratories have developed their own molecular assays or adapted published protocols, often making slight modifications to fit their specific study purposes. The sensitivity and specificity of a molecular test depend on the target gene, primer sequences, types of molecular test, DNA extraction method, and sampling methods. We reviewed 120 articles published between 2000 and 2020 to compile information on the molecular detection of C. psittaci in birds. Of the ten genomic targets currently available to detect C. psittaci in birds, the ompA gene was the most widely used. In published surveillance studies, of the fourteen molecular test types, conventional PCR and quantitative PCR were applied the most. A testing strategy using a hierarchical approach that includes molecular tests of genus- and species-specific targets is recommended to detect other avian chlamydial species besides the well-recognized C. psittaci. Samples should be sourced from both the respiratory and gastrointestinal tracts whenever possible for better accuracy. High-quality DNA can be obtained when the sample is preserved in optimal medium and temperature, and an optimized DNA extraction protocol is applied. Standardization and validation of molecular Chlamydia tests are needed to enhance the comparability and reliability of assays to detect C. psittaci and other chlamydiae species in birds.RESEARCH HIGHLIGHTSHierarchical molecular testing is recommended for the detection of avian C. psittaci.Key molecular tests for surveillance were conventional PCR and quantitative PCR.The most used genomic target to detect C. psittaci in birds was the ompA gene.

Environmental stressors and zoonoses in the Arctic: Learning from the past to prepare for the future

The risk of zoonotic disease transmission from animals to humans is elevated for people in close contact with domestic and wild animals. About three-quarters of all known human infectious diseases are zoonotic, and potential health impacts of these diseases are higher where infectious disease surveillance and access to health care and public health services are limited. This is especially the case for remote circumarctic regions, where drivers for endemic, emerging, and re-emerging zoonotic diseases include anthropogenic influences, such as pollution by long-range transport of industrial chemicals, climate change, loss of biodiversity and ecosystem alterations. In addition to these, indirect effects including natural changes in food web dynamics, appearance of invasive species and thawing permafrost also affect the risk of zoonotic disease spill-over. In other words, the Arctic represents a changing world where pollution, loss of biodiversity and habitat, and maritime activity are likely driving forward occurrence of infectious diseases. As a broad international consortium with a wide range of expertise, we here describe a selection of case studies highlighting the importance of a One Health approach to zoonoses in the circumarctic, encompassing human health, animal health, and environmental health aspects. The cases highlight critical gaps in monitoring and current knowledge, focusing on environmental stressors and lifestyle factors, and they are examples of current occurrences in the Arctic that inform on critically needed actions to prepare us for the future. Through these presentations, we recommend measures to enhance awareness and management of existing and emerging zoonoses with epidemic and pandemic potential while also focusing on the impacts of various environmental stressors and lifestyle factors on zoonoses in the Arctic.

Chlamydiosis in Animals

The Chlamydiaceae family consists of Gram-negative, obligate intracellular bacteria that replicate within the cells of a diverse range of hosts. These hosts include domesticated animals such as cats, dogs, and livestock, as well as wildlife like koalas and birds, exotic species such as reptiles and amphibians, and humans. Chlamydial infection can result in various clinical signs, including respiratory diseases, reproductive failures, ocular pathologies, and enteritis, though the infected organism may remain asymptomatic. In recent years, chlamydial nomenclature has undergone several revisions due to the wide range of hosts, the frequent discovery of novel strains, and the reclassification of existing ones. Given this and the clinical significance of these infections, ranging from asymptomatic to fatal, an updated review is essential. This article outlines key characteristics of Chlamydia species and provides an updated overview of their nomenclature, offering a concise reference for future research on chlamydial diseases.

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.

Whole-genome sequencing of Chlamydia psittaci from Australasian avian hosts: A genomics approach to a pathogen that still ruffles feathers

Chlamydia psittaci is a globally distributed veterinary pathogen with zoonotic potential. Although C. psittaci infections have been reported in various hosts, isolation and culture of Chlamydia is challenging, hampering efforts to produce contemporary global C. psittaci genomes. This is particularly evident in the lack of avian C. psittaci genomes from Australia and New Zealand. In this study, we used culture-independent probe-based whole-genome sequencing to expand the global C. psittaci genome catalogue. Here, we provide new C. psittaci genomes from two pigeons, six psittacines, and novel hosts such as the Australian bustard (Ardeotis australis) and sooty shearwater (Ardenna grisea) from Australia and New Zealand. We also evaluated C. psittaci genetic diversity using multilocus sequence typing (MLST) and major outer membrane protein (ompA) genotyping on additional C. psittaci-positive samples from various captive avian hosts and field isolates from Australasia. We showed that the first C. psittaci genomes sequenced from New Zealand parrots and pigeons belong to the clonal sequence type (ST)24 and diverse 'pigeon-type' ST27 clade, respectively. Australian parrot-derived strains also clustered in the ST24 group, whereas the novel ST332 strain from the Australian bustard clustered in a genetically diverse clade of strains from a fulmar, parrot, and livestock. MLST and ompA genotyping revealed ST24/ompA genotype A in wild and captive parrots and a sooty shearwater, whilst 'pigeon-types' (ST27/35 and ompA genotypes B/E) were found in pigeons and other atypical hosts, such as captive parrots, a little blue penguin/Kororā (Eudyptula minor) and a zebra finch (Taeniopygia guttata castanotis) from Australia and New Zealand. This study provides new insights into the global phylogenomic diversity of C. psittaci and further demonstrates the multi-host generalist capacity of this pathogen.

Emerging and well-characterized chlamydial infections detected in a wide range of wild Australian birds

Birds can act as successful long-distance vectors and reservoirs for numerous zoonotic bacterial, parasitic and viral pathogens, which can be a concern given the interconnectedness of animal, human and environmental health. Examples of such avian pathogens are members of the genus Chlamydia. Presently, there is a lack of research investigating chlamydial infections in Australian wild and captive birds and the subsequent risks to humans and other animals. In our current study, we investigated the prevalence and genetic diversity of chlamydial organisms infecting wild birds from Queensland and the rate of co-infections with beak and feather disease virus (BFDV). We screened 1114 samples collected from 564 different birds from 16 orders admitted to the Australia Zoo Wildlife Hospital from May 2019 to February 2021 for Chlamydia and BFDV. Utilizing species-specific quantitative polymerase chain reaction (qPCR) assays, we revealed an overall Chlamydiaceae prevalence of 29.26% (165/564; 95% confidence interval (CI) 25.65-33.14), including 3.19% (18/564; 95% CI 2.03-4.99%) prevalence of the zoonotic Chlamydia psittaci. Chlamydiaceae co-infection with BFDV was detected in 9.75% (55/564; 95% CI 7.57-12.48%) of the birds. Molecular characterization of the chlamydial 16S rRNA and ompA genes identified C. psittaci, in addition to novel and other genetically diverse Chlamydia species: avian Chlamydia abortus, Ca. Chlamydia ibidis and Chlamydia pneumoniae, all detected for the first time in Australia within a novel avian host range (crows, figbirds, herons, kookaburras, lapwings and shearwaters). This study shows that C. psittaci and other emerging Chlamydia species are prevalent in a wider range of avian hosts than previously anticipated, potentially increasing the risk of spill-over to Australian wildlife, livestock and humans. Going forward, we need to further characterize C. psittaci and other emerging Chlamydia species to determine their exact genetic identity, potential reservoirs, and factors influencing infection spill-over.

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.

A New SNP-Based Genotyping Method for C. psittaci: Application to Field Samples for Quick Identification

Chlamydia (C.) psittaci is the causative agent of avian chlamydiosis and human psittacosis. In this study, we extracted single-nucleotide polymorphisms (SNPs) from the whole genome sequences of 55 C. psittaci strains and identified eight major lineages, most of which are host-related. A combined PCR/high-resolution melting (HRM) assay was developed to screen for eight phylogenetically informative SNPs related to the identified C. psittaci lineages. The PCR-HRM method was validated on 11 available reference strains and with a set of 118 field isolates. Overall, PCR-HRM clustering was consistent with previous genotyping data obtained by ompA and/or MLST analysis. The method was then applied to 28 C. psittaci-positive samples from animal or human cases. As expected, PCR-HRM typing results from human samples identified genotypes linked to ducks and pigeons, a common source of human exposure, but also to the poorly described Mat116-like genotype. The new genotyping method does not require time-consuming sequencing and allows a quick identification of the source of infection.

The Importance of Animal and Marine Fat in the Faroese Cuisine: The Past, Present, and Future of Local Food Knowledge in an Island Society

Since ecological and climatic conditions limit the possibilities for cereal production, the old-established Faroese traditional food system is principally based on the utilization of animal protein and fat. The diet of the islanders has thus been adapted to the specific environmental circumstances of the area. Historically, fat has provided a high energy and nutritious food source for the hard-working sheep farmers and fishermen. Fat procured from both land and marine animals has formed a vital part of the local food culture. Apart from the insubstantial amount of butter produced in the Faroe Islands, tallow from sheep, fish fat and liver from codfishes, and the blubber from the long-finned pilot whale, has been widely utilized within the households. During the last century, Faroese diet has changed due to external factors such as closer integration into the world economy, modernization, and improved household economy. Although butter, cheese and other dairy products as well as margarine and vegetable oil are nowadays readily available in the convenience shops and supermarkets, tallow, and whale blubber continue to be part and parcel of many of the islanders' cuisine. Today, however, such products are not primarily consumed for their energy content. Instead, it can be seen as a contemporary and regional expression of appraisal toward Faroese cuisine. Appreciating and consuming local food has become an important part of expressing Faroese cultural identity. The traditional diet therefore links the islanders with their history. However, the preparation of Faroese food products is highly dependent on traditional knowledge of how to extract different types of animal fat and process it into locally made dishes. Thus, the long-term survival of traditional Faroese gastronomy is contingent on the maintenance and continuation of this knowledge.