Detection of atypical Chlamydiaceae in roe deer ( Capreolus capreolus )

Detection of a range of genetically diverse chlamydiae in Australian domesticated and wild ungulates

Chlamydiae are globally widespread obligate intracellular bacteria, which several species are a well-recognized threat to human and animal health. In Australia, the most successful chlamydial species are the infamous koala pathogen C. pecorum, and C. psittaci, an emerging pathogen associated with zoonotic events. Little is known about infections caused by other chlamydial organisms in Australian livestock or wildlife. Considering that these hosts can be encountered by humans at the animal/human interface, in this study, we investigated genetic diversity of chlamydial organisms infecting Australian domesticated and wild ungulates. A total of 185 samples from 129 domesticated (cattle, horses, sheep, and pigs) and 29 wild (deer) ungulate hosts were screened with C. pecorum and C. psittaci species-specific assays, followed by a screen with pan-Chlamydiales assay. Overall, chlamydial DNA was detected in 120/185 (65%) samples, including all ungulate hosts. Species-specific assays further revealed that C. pecorum and C. psittaci DNA were detected in 27% (50/185) and 6% (11/185) of the samples, respectively, however from domesticated hosts only. A total of 46 "signature" 16S rRNA sequences were successfully resolved by sequencing and were used for phylogenetic analyses. Sequence analyses revealed that genetically diverse novel as well as traditional chlamydial organisms infect an expanded range of ungulate hosts in Australia. Detection of the C. psittaci and C. pecorum in livestock, and novel taxa infecting horses and deer raises questions about the genetic make-up and pathogenic potential of these organisms, but also concerns about risks of spill-over between livestock, humans, and native wildlife.

Prevalence, Diagnosis, and Vaccination Situation of Animal Chlamydiosis in China

Since the first case of Chlamydia infection in duck had been reported in 1956 and the first case from domestic animal had been reported in 1979 in China, the chlamydia prevalence in China was heavily according to the published data. The Chlamydia in avian prevalence has been reported at least 11 provinces, Chlamydia in sheep and goats at least 11 provinces, in swine at least 15 provinces, in cows at least 13 provinces and in yaks at least 5 provinces with result of IHA detection. Different diagnostic method such as CFT, ELISA and ABC-ELISA (avidin-biotin-complex ELISA) had been established besides IHA. The inactivated vaccines have been developed with isolated strains from sheep, goats, swine and cows. These inactivated vaccines have been used since 1980s and Chlamydia prevalence in China has been successfully controlled in domestic animal. However, the inactivated vaccines of Chlamydia isolated from avian species have not been successful, although a series of experimental vaccine have been done. Due to the unsustainable eradication plan of Chlamydia in China, sporadic outbreak in animal would happen if the vaccinations were suspended and economy lose in some farmers. Although Chlamydia prevalence in China has a long history, however, almost all published studies are in Chinese, which, in some degree, blocked scientists in other countries to understand the prevalence situation and control measures of Chlamydia in China.

Prevalence and Risk Factors of Brucellosis, Chlamydiosis, and Bluetongue Among Sika Deer in Jilin Province in China

Brucellosis and chlamydiosis are important zoonotic diseases and bluetongue virus (BTV) is an arthropod-borne viral disease of ruminants. They are widely distributed around the world, cause large economic losses, and significant harmful effects on humans. However, epidemiological information relating to transmission from commercial sika deer in China is limited. Therefore, from 2016 to 2017, 458 sika deer blood samples were collected from three cities in Jilin Province in China. The Brucella antigen and specific antibodies to Chlamydia and BTV were examined using RT-PCR, indirect hemagglutination assay, and ELISA, respectively. The prevalence of Brucella was found to be 12.9% (59/458) and the seroprevalence of Chlamydia and BTV was 14.4% (66/458) and 17.0% (78/458), respectively. Seasonality was considered a risk factor for the presence of Brucella or BTV in sika deer and the region was considered a risk factor for Chlamydia infection. These data provides reference values for both further research and disease control.

A Review on Chlamydial Diseases in Animals: Still a Challenge for Pathologists?

Chlamydiae have a worldwide distribution causing a wide range of diseases in human hosts, livestock, and companion animals as well as in wildlife and exotic species. Moreover, they can persist in their hosts as asymptomatic infections for extended periods of time. The introduction of molecular techniques has revolutionized the Chlamydia field by expanding the host range of known chlamydial species but also by discovering new species and even new families of bacteria in the broader order Chlamydiales. The wide range of hosts, diseases, and tissues affected by chlamydiae complicate the diagnosis such that standard diagnostic approaches for these bacteria are rare. Bacteria of the Chlamydiales order are small and their inclusions are difficult to detect by standard microscopy. With the exception of avian and ovine chlamydiosis, macroscopic and/or histologic changes might not be pathognomic or indicative for a chlamydial infection or even not present at all. Moreover, detection of chlamydial DNA in specimens in the absence of other methods or related pathological lesions questions the significance of such findings. The pathogenic potential of the majority of recently identified Chlamydia-related bacteria remains largely unknown and awaits investigation through experimental or natural infection models including histomorphological characterization of associated lesions. This review aims to summarize the historical background and the most important developments in the field of animal chlamydial research in the past 5 years with a special focus on pathology. It will summarize the current nomenclature, present critical thoughts about diagnostics, and give an update on chlamydial infections in domesticated animals such as livestock, companion animals and birds, as well as free-ranging and captive wild animals such as reptiles, fish, and marsupials.

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.

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.

Chlamydia-Like Organisms (CLOs) in Finnish Ixodes ricinus Ticks and Human Skin

Ticks carry several human pathogenic microbes including Borreliae and Flavivirus causing tick-born encephalitis. Ticks can also carry DNA of Chlamydia-like organisms (CLOs). The purpose of this study was to investigate the occurrence of CLOs in ticks and skin biopsies taken from individuals with suspected tick bite. DNA from CLOs was detected by pan-Chlamydiales-PCR in 40% of adult ticks from southwestern Finland. The estimated minimal infection rate for nymphs and larvae (studied in pools) was 6% and 2%, respectively. For the first time, we show CLO DNA also in human skin as 68% of all skin biopsies studied contained CLO DNA as determined through pan-Chlamydiales-PCR. Sequence analyses based on the 16S rRNA gene fragment indicated that the sequences detected in ticks were heterogeneous, representing various CLO families; whereas the majority of the sequences from human skin remained "unclassified Chlamydiales" and might represent a new family-level lineage. CLO sequences detected in four skin biopsies were most closely related to "uncultured Chlamydial bacterium clones from Ixodes ricinus ticks" and two of them were very similar to CLO sequences from Finnish ticks. These results suggest that CLO DNA is present in human skin; ticks carry CLOs and could potentially transmit CLOs to humans.