Occurrence of Chlamydiaceae spp. in a wild boar (Sus scrofa L.) population in Thuringia (Germany)

Generation of Tetracycline and Rifamycin Resistant Chlamydia Suis Recombinants

The Chlamydiaceae are a family of obligate intracellular, gram-negative bacteria known to readily exchange DNA by homologous recombination upon co-culture in vitro, allowing the transfer of antibiotic resistance residing on the chlamydial chromosome. Among all the obligate intracellular bacteria, only Chlamydia (C.) suis naturally integrated a tetracycline resistance gene into its chromosome. Therefore, in order to further investigate the readiness of Chlamydia to exchange DNA and especially antibiotic resistance, C. suis is an excellent model to advance existing co-culture protocols allowing the identification of factors crucial to promote homologous recombination in vitro. With this strategy, we co-cultured tetracycline-resistant with rifamycin group-resistant C. suis, which resulted in an allover recombination efficiency of 28%. We found that simultaneous selection is crucial to increase the number of recombinants, that sub-inhibitory concentrations of tetracycline inhibit rather than promote the selection of double-resistant recombinants, and identified a recombination-deficient C. suis field isolate, strain SWA-110 (1-28b). While tetracycline resistance was detected in field isolates, rifampicin/rifamycin resistance (RifR) had to be induced in vitro. Here, we describe the protocol with which RifR C. suis strains were generated and confirmed. Subsequent whole-genome sequencing then revealed that G530E and D461A mutations in rpoB, a gene encoding for the β-subunit of the bacterial RNA polymerase (RNAP), was likely responsible for rifampicin and rifamycin resistance, respectively. Finally, whole-genome sequencing of recombinants obtained by co-culture revealed that recombinants picked from the same plate may be sibling clones and confirmed C. suis genome plasticity by revealing variable, apparently non-specific areas of recombination.

A recombinase polymerase amplification-based assay for rapid detection of Chlamydia psittaci

Chlamydia psittaci is a zoonotic agent of systemic wasting disease in birds and atypical pneumonia in mammalians including humans, constituting a public health risk. A rapid diagnostic assay would be beneficial in screening C. psittaci in the field. In this study, we developed a probe-based recombinase polymerase amplification (RPA) assay for the rapid detection of C. psittaci. The specific primer pairs and probe targeting the conserved region of the outer membrane protein A gene were designed and applied to the real-time real-time RPA assay. The test can be performed at 39°C for 20 min using a portable device, with sensitivities approaching 100 copies of DNA molecules per reaction, with no cross-reaction with other pathogens. The clinical performance of the RPA assay was evaluated in an outbreak of C. psittaci and has high accuracy levels in field applications. The epidemic C. psittaci strains were classed into 2 genotypes: A and C. Collectively, this study offers a promising approach in screening for C. psittaci both in a laboratory setting and in field settings, and RPA can be used as an effective clinical test to monitor outbreaks in domestic fowl populations.

The occurrence and pathology of chlamydiosis in the male reproductive tract of non-human mammals: A review

Organisms belonging to the Family Chlamydiaceae are responsible for a broad range of diseases in humans, livestock, companion animals and non-domestic species. Infection of the reproductive organs can cause a range of syndromes of which sub- and infertility are the most frequently observed clinical manifestations. While the gross and histological lesions associated with the isolation of Chlamydiaceae from the non-human female reproductive tract are well documented, little attention has been given to the pathological effects of this infection in the male genital system. As such, the occurrence and importance of Chlamydia-associated disease in male non-human mammalian species is less well documented. In order to improve our understanding of the significance of chlamydiosis in domestic, laboratory and wild animals, this review provides an up-to-date summary of Chlamydia-associated male reproductive pathology, whether that infection occurs naturally or experimentally. Although most lesions in males are described as incidental and of minor significance, results of recent studies suggest that infection with Chlamydiaceae can adversely impact male fertility and/or be instrumental in disease transmission. Although in humans, bulls and mice Chlamydia infection has been associated with morphological and functional abnormalities of the spermatozoa, this review will focus on the gross and histological findings linked to the colonisation of the genital system by this pathogen. Advances in our understanding of male reproductive chlamydiosis are necessary for diagnostic and therapeutic strategies, as well as epidemiological and conservation studies.

PREVALENCE OF CHLAMYDIACEAE AND TETRACYCLINE RESISTANCE GENES IN WILD BOARS OF CENTRAL EUROPE

Our aim was to investigate the occurrence and distribution of Chlamydia suis and other Chlamydiaceae in the wild boar (Sus scrofa) population of Switzerland and Northern Italy and the detection of tetracycline resistance genes by PCR. We collected a total of 471 conjunctival swabs (n=292), rectal swabs (n=147), and lung tissue samples (n=32) belonging to 292 wild boars. The prevalence of Chlamydiaceae in the investigated wild boar populations was very low (1.4%, 4/292). We found C. suis in rectal or conjunctival swabs but not in lung samples. The low chlamydial prevalence might be attributed to limited contacts between wild boars and outdoor domestic pigs due to strict biosecurity measures or limited numbers of rural pig herds. The tetA(C) gene fragment was detected in six samples, which were all negative for Chlamydiaceae, and was probably not of chlamydial origin but more likely from other bacteria. The low tetracycline resistance rate in wild boar might be explained by the lack of selective pressure. However, transmission of resistance genes from domestic pigs to wild boar or selective pressure in the environment could lead to the development and spread of tetracycline-resistant C. suis strains in wild boars.

First Report of Chlamydia Seroprevalence in Slaughter Pigs in Shandong Province, Eastern China

Chlamydia, a kind of obligate intracellular Gram-negative bacteria, can infect humans and animals worldwide, including pigs. However, the information on Chlamydia infection is unavailable in pigs in Shandong province, eastern China. To assess the seroprevalence and risk factors of Chlamydia infection in pigs in Shandong province, eastern China, a total of 2108 serum samples of slaughter pigs were collected between January 2017 and December 2018, and specific antibodies against Chlamydia were detected by the indirect hemagglutination assay. The overall Chlamydia seroprevalence was 24.15% (509/2108, 95% confidence interval: 22.32-25.97). Species, sampling regions, and rearing systems of pigs were considered as risk factors for Chlamydia infection through statistical analysis by SAS analysis (p < 0.05). These results indicated that Chlamydia is highly prevalent in slaughter pigs in Shandong province, eastern China, and may pose a potential risk for human health. To our knowledge, this is the first investigation of Chlamydia seroprevalence in slaughter pigs in Shandong province, eastern China. Moreover, this is the first report to compare the Chlamydia seroprevalence between domestic pigs and farmed wild boars in a same study, which may provide important data for preventing and controlling Chlamydia infection in pigs in China.

A parrot-type Chlamydia psittaci strain is in association with egg production drop in laying ducks

Chlamydophila psittaci (C. psittaci) is an avian pathogen associated with systemic wasting disease in birds, as well as a public health risk. Although duck-related cases of psittacosis have been reported, the pathogenicity and shedding status of C. psittaci in ducks are unclear. In this study, we reported that C. psittaci (genotype A) is responsible for a disease outbreak characterized by poor laying performance and severe lesions in multiple organs of ducks. Oral administration of antibiotic, doxycycline, was found to effectively control the C. psittaci infection in laying ducks. Collectively, our new findings provide evidence that C. psittaci was the major pathogen responsible for the outbreak of this disease in ducks. In order to reduce economic losses incurred by this disease, effective control measures must be taken to prevent infection in laying duck farms.

First Report of Chlamydia Seroprevalence in Farmed Wild Boars in China

Chlamydia is Gram-negative obligate bacterium, which can cause human diseases worldwide and has huge economic impact on animals. It is yet to know whether farmed wild boars are infected with Chlamydia in China. To assess risk factors of Chlamydia infection in farmed wild boars in China, from April 2015 to February 2016, a total of 837 serum samples of farmed wild boars were collected in Jilin province, northeastern China, and antibodies against Chlamydia were examined by the indirect hemagglutination assay. The investigation showed that antibodies to Chlamydia were detected in 332 (39.67%, 95% CI 33.36-42.98) of 837 serum samples of farmed wild boars, seroprevalence ranged from 33.71% to 44.42% among different regions and the differences were statistically significant by SPSS analysis (p = 0.0248). These results indicated that Chlamydia is highly prevalent in farmed wild boars in Jilin province, northeastern China, and may pose a potential risk for human health. To our knowledge, this is the first report of Chlamydia seroprevalence in farmed wild boars in China, which provided baseline data for preventing and controlling Chlamydia infection in wild boars in China.

Sero-prevalence of chlamydiosis in cattle and selected wildlife species at a wildlife/livestock interface area of Zimbabwe

A study was conducted to investigate the seroprevalence and associated risk factors of Chlamydia abortus infection in cattle and some selected wildlife species at selected interface areas at the periphery of the Great Limpopo Transfrontier Conservation Area in Zimbabwe. Three study sites were selected based on the type of livestock-wildlife interface, porous livestock-wildlife interface (unrestricted), non-porous livestock-wildlife interface (restricted by fencing), and livestock-wildlife non-interface (totally absent or control). Sera were collected from cattle aged ≥ 2 years representing both female and intact male. Sera were also collected from selected wild ungulates from Mabalauta (porous interface) and Chipinda Pools (non-interface) areas of the Gonarezhou National Park. Sera were tested for antibodies to Chlamydia abortus using a CFT. A X ² test was used to assess differences between categories and p < 0.05 was considered as significant. In cattle, the overall seroprevalence was 32.7% (327/1011; 95% CI 29.5-35.3). A significantly lower seroprevalence was recorded for the porous interface (24.2%) compared to the non-porous (42.5%) (p < 0.0001) and the non-interface (36.2%) (p = 0.001). Overall, the wet season recorded a significantly (p = 0.015) higher seroprevalence than the dry season. In wildlife, antibodies were detected in buffaloes (47.7%) and impalas (43.8%) but not in kudus. Buffaloes from Chipinda Pools (53.4%) had a significantly (p = 0.036) higher seroprevalence than those from Mabalauta (26.1%). The results established the presence of chlamydiosis in cattle and selected wildlife and that independent infections may be maintained in buffalo populations. Further studies are required to clarify chlamydiae circulating between cattle and wildlife.

Suidae and Tayassuidae

The Suidae and Tayassuidae live on all continents except Antarctica. True wild boars were indigenous to Europe and Asia and are the ancestors to the domestic pig; with whom they share the same scientific name Sus scrofa. Wild boars have been introduced to the Americas and many islands. Because of the close genetic relationship, in many areas they have interbred with domestic pigs and formed considerable populations of feral suids that represent wild boar and feral pig crosses. Wild suid populations are relatively hardy and most disease research has been focused on their potential as a reservoir for diseases of concern for commercial pig production. The Togian Island babirusa, pygmy hog, Visayan warty pig, Javan warty pig, and Chacoan peccary are endangered. For all species, hunting, habitat loss, and hybridization are important threats to conservation.

Recombinant protein CPSIT_0846 induces protective immunity against Chlamydia psittaci infection in BALB/c mice

Chlamydia psittaci is an obligate intracellular bacteria that causes respiratory disease in poultry and humans. Currently, there are no licensed vaccines against chlamydial infection in humans. The transmembrane head protein CPSIT_0846 of C. psittaci is a putative member of the larger Inc protein family. In this study, we investigated immunogenicity and protective efficacy of the recombinant CPSIT_0846 protein in BALB/c mice. Mice immunized with CPSIT_0846 developed strong T-lymphocyte responses that were recalled by the immunogen CPSIT_0846 in an in vitro restimulation assay. These T cells displayed a strong Th1-biased cytokine profile with high levels of IFN-γ. At the same time, a strong humoral immune response was also detected in the immunized mice with high titers of Chlamydia psittaci-specific serum IgG antibodies. More importantly, the robust immune responses correlated well with significantly reduced chlamydial burden and inflammatory pathology in the mouse lungs upon an airway challenge infection. The above results together suggest that the CPSIT_0846 protein may be a potential vaccine candidate antigen for inducing protection against C. psittaci infection and disease in the airway.

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 prevalence in Polish pig herds

Chlamydiae are frequently encountered intracellular Gram-negative bacteria. In pigs, these bacteria in combination with other pathogens contribute to the induction of a multi-aetiological syndrome. One of the major characteristics of Chlamydia spp. is their ability to cause prolonged, often subclinical infections. While the economic consequences of Chlamydia spp. infections in pig farms are not fully established, we know that reproductive disorders and other syndromes correlated with Chlamydia infection can lead to financial loss as a result of a reduction in pork production. Additionally, Chlamydia spp. presents a potential zoonotic hazard, therefore determining the prevalence of Chlamydia in pig populations is critical. In the present study 97 pig herds from Poland were involved. To determine the prevalence of Chlamydia PCR and CFT tests were used. In total 797 vaginal samples, 797 conjunctival samples, and 235 serum samples were collected and tested. The study took place from 2011 to 2014. We found Chlamydia spp. present in 71·2% of all tested farms. The percentage of animals testing positive on any given farm varied from 20% to 100%.

Prevalence of Chlamydial Infections in Fattening Pigs and Their Influencing Factors

Chlamydial infections in pigs are associated with respiratory disease, diarrhea, conjunctivitis and other pathologies. The aim of this study was to define the prevalence of Chlamydiaceae in Swiss fattening pigs by applying sensitive and specific detection methods and to correlate prior antibiotic treatment and farm related factors with differences in prevalence. Conjunctival and fecal swabs were collected from 636 pigs in 29 Swiss fattening pig farms with and without antibiotic treatment, at the beginning and the end of the fattening period. The swabs were screened by real-time PCR for Chlamydiaceae. For the chlamydial detection and species-identification, a DNA-microarray analysis was performed. All farms were positive for Chlamydiaceae with 94.3 and 92.0% prevalence in fecal swabs as well as 45.9 and 32.6% in conjunctival swabs at the first and second time points, respectively. Antibiotic treatment could not clear the infection on herd level. Potential contact with wild boars was a significant risk factor, while hygiene criteria did not influence chlamydial prevalence. A correlation of chlamydial positivity to diarrhea, but not to conjunctivitis was evident. Chlamydia suis was the predominant species. Mixed infections with C. suis and C. pecorum were common, with a substantial increase in C. pecorum positivity at the end of the fattening period, and this finding was associated with ruminant contact. C. abortus was detected in one conjunctival swab. In this study, C. suis inhabited the intestinal tract of nearly all examined pigs, implying a long-term infection. C. pecorum was also common and might be transmitted to pigs by ruminants.

Chlamydia psittaci comparative genomics reveals intraspecies variations in the putative outer membrane and type III secretion system genes

Chlamydia psittaci is an obligate intracellular bacterium that can cause significant disease among a broad range of hosts. In humans, this organism may cause psittacosis, a respiratory disease that can spread to involve multiple organs, and in rare untreated cases may be fatal. There are ten known genotypes based on sequencing the major outer-membrane protein gene, ompA, of C. psittaci. Each genotype has overlapping host preferences and virulence characteristics. Recent studies have compared C. psittaci among other members of the Chlamydiaceae family and showed that this species frequently switches hosts and has undergone multiple genomic rearrangements. In this study, we sequenced five genomes of C. psittaci strains representing four genotypes, A, B, D and E. Due to the known association of the type III secretion system (T3SS) and polymorphic outer-membrane proteins (Pmps) with host tropism and virulence potential, we performed a comparative analysis of these elements among these five strains along with a representative genome from each of the remaining six genotypes previously sequenced. We found significant genetic variation in the Pmps and tbl3SS genes that may partially explain differences noted in C. psittaci host infection and disease.

Seroprevalence and Risk Factors of Chlamydia Infection in Domestic Rabbits (Oryctolagus cuniculus) in China

Chlamydia spp. are obligate intracellular bacteria distributed all over the world, known to cause various forms of diseases in animals and humans. In the present study, a serological survey was conducted to detect the seroprevalence and risk factors associated with rabbit chlamydiosis in northeast China, including Liaoning province, Jilin province, Heilongjiang province, and Inner Mongolia Autonomous Region. Antibodies to Chlamydia were determined by indirect hemagglutination assay (IHA). The overall seroprevalence was estimated at 17.88% in total of 800 blood samples. The Chlamydia seroprevalence varied in domestic rabbits from different factors, and genders of domestic rabbits were considered as major risk factors associated with Chlamydia infection. Our study revealed a widespread and high prevalence of Chlamydia infection in domestic rabbits in northeast China, with higher exposure risk in female domestic rabbits. These findings suggested the potential importance of domestic rabbits in the transmission of zoonotic Chlamydia infection, and thus Chlamydia should be taken into consideration in diagnosing rabbit diseases. To our knowledge, there is no report of Chlamydia infection in domestic rabbits in China and the results extend the host range for Chlamydia, which has important implications for public health and the local economy.

Chlamydia psittaci: update on an underestimated zoonotic agent

Chlamydia (C.) psittaci is an economically relevant pathogen in poultry and pet birds, where it causes psittacosis/ornithosis, and also a human pathogen causing atypical pneumonia after zoonotic transmission. Despite its well-documented prevalence, the agent has received less attention by researchers than other Chlamydia spp. in the last decades. In the present paper, we review recently published data on C. psittaci infection and attempt to single out characteristic features distinguishing it from related chlamydial agents. It is remarkable that C. psittaci is particularly efficient in disseminating in the host organism causing systemic disease, which occasionally can take a fulminant course. At the cellular level, the pathogen's broad host cell spectrum (from epithelial cells to macrophages), its rapid entry and fast replication, proficient use of intracellular transport routes to mitochondria and the Golgi apparatus, the pronounced physical association of chlamydial inclusions with energy-providing cell compartments, as well as the subversive regulation of host cell survival during productive and persistent states facilitate the characteristic efficient growth and successful host-to-host spread of C. psittaci. At the molecular level, the pathogen was shown to upregulate essential chlamydial genes when facing the host immune response. We hypothesize that this capacity, in concert with expression of specific effectors of the type III secretion system and efficient suppression of selected host defense signals, contributes to successful establishment of the infection in the host. Concerning the immunology of host-pathogen interactions, C. psittaci has been shown to distinguish itself by coping more efficiently than other chlamydiae with pro-inflammatory mediators during early host response, which can, to some extent, explain the effective evasion and adaptation strategies of this bacterium. We conclude that thorough analysis of the large number of whole-genome sequences already available will be essential to identify genetic markers of the species-specific features and trigger more in-depth studies in cellular and animal models to address such vital topics as treatment and vaccination.

Seroprevalence and genotype of Chlamydia in pet parrots in China

Parrots are one of the most popular pet birds in China, and can harbour Chlamydia which has significance for human and animal health. We investigated, by indirect haemagglutination assay, the seroprevalence of Chlamydia infection in four species of parrots, namely budgerigars (Melopsittacus undulatus), lovebirds (Agapornis sp.), cockatiels (Nymphicus hollandicus) and Alexandrine parakeets (Psittacula eupatria) that were collected from Weifang and Beijing cities, North China and explored the association between potential risk factors and chlamydial seropositivity. We further determined the genotype of Chlamydia in 21 fresh faecal samples based on the ompA sequence by reconstruction of phylogenetic relationships. Of the 311 parrots examined, 35·37% (95% confidence interval 30·06–40·68) were seropositive, and species, gender, age, season and geographical location were identified as risk factors. Two PCR-positive samples represented Chlamydia psittaci genotype A. The occurrence of C. psittaci genotype A in the droppings of two pet parrots in China suggests potential environmental contamination with Chlamydiaceae and may raise a public health concern.

Infection, disease, and transmission dynamics in calves after experimental and natural challenge with a Bovine Chlamydia psittaci isolate

Chlamydia (C.) psittaci is the causative agent of psittacosis, a zoonotic disease in birds and man. In addition, C. psittaci has been repeatedly found in domestic animals and is, at least in calves, also able to induce respiratory disease. Knowledge about transmission routes in cattle herds is still deficient, and nothing is known about differences in host response after either experimental or natural exposure to C. psittaci. Therefore, our recently developed respiratory infection model was exploited to evaluate (i) the presence of the pathogen in blood, excretions and air, (ii) the possibility of transmission and (iii) clinical symptoms, acute phase and immune response until 5 weeks after exposure. In this prospective study, intrabronchial inoculation of 10⁸ inclusion-forming units of C. psittaci (n = 21 calves) led to reproducible acute respiratory illness (of approximately one week), accompanied by a systemic inflammatory reaction with an innate immune response dominated by neutrophils. Excretion and/or exhalation of the pathogen was sufficient to transmit the infection to naïve sentinel calves (n = 3) co-housed with the infected animals. Sentinel calves developed mild to subclinical infections only. Notably, excretion of the pathogen, predominantly via feces, occurred more frequently in animals naturally exposed to C. psittaci (i.e. sentinels) as compared to experimentally-inoculated calves. The humoral immune response was generally weak, and did not emerge regularly following experimental infection; however, it was largely absent after naturally acquired infection.

Ocular lesions associated with Chlamydia suis in a wild boar piglet (Sus scrofa) from a semi-free range population in Spain

The role of the wild boar (Sus scrofa) as a reservoir for a large number of pathogens that can affect both domestic animals and humans has been widely studied in the last few years. However, the impact of some of these pathogens on the health of wild boar populations is still being determined. This article presents a clinical case of severe bilateral keratoconjunctivitis affecting a 2-mo-old piglet from a semi-free range population in Spain. Histopathologic and microbiologic analysis revealed lesions in the cornea, choroid, and optical nerve, and Chlamydia suis was detected in the eyes bilaterally. The visual handicap resulting from this type of lesion greatly affects the survival of this affected piglet.

First report of Chlamydiaceae seroprevalence in Tibetan pigs in Tibet, China

The seroprevalence of Chlamydiaceae infection in Tibetan pigs in Tibet, China, was examined by indirect hemagglutination assay (IHA), between April, 2010, and December, 2010. A total of 71 of 427 serum samples (16.63%, 95% confidence interval [CI] 15.31-17.95] were positive for Chlamydiaceae antibodies. Forty Chlamydiaceae seropositives from 232 samples were recorded in sera from Nyingchi (17.24%, 95% CI 15.40-19.08) and 31 positives were recorded in 195 serum samples from Mainling (15.90%, 95% CI 14.02-17.78). The investigation showed that the prevalence in female animals was 17.61% (95% CI 15.22-20.00), and in male animals it was 12.72% (95% CI 11.07-14.37). The prevalence ranged from 0% to 20.61% (95% CI 17.81-23.48) among different age groups, with a higher prevalence in growing pigs (p<0.01). The results indicated that Chlamydiaceae infection was widespread in Tibetan pigs in Tibet, China, which is of public health concern in this region of the world. To our knowledge, this is the first report of Chlamydiaceae seroprevalence in Tibetan pigs in Tibet, China.

Detection and identification of Chlamydophila psittaci in asymptomatic parrots in Poland

Background

Psittacosis, an avian disease caused by Chlamydophila psittaci, can manifest as an acute, protracted, or chronic illness, but can also be asymptomatic. C. psittaci can persist in the host for months to years, often without causing obvious illness, and therefore poses a threat for zoonotic outbreak. We investigated the prevalence of C. psittaci from 156 tracheal swab samples from 34 different species of parrots in Poland, and determined the genotype of strains from the positive samples.

Results

An overall prevalence of 10.3% was observed using two different PCR assays, both providing similar results. Thirteen of the PCR-positive samples were genotype A, two were genotype B, and one could not be classified.

Conclusions

These results indicate widespread dissemination of C. psittaci in Polish psittacine populations, without any clinical signs of chlamydiosis, and hence could pose a zoonotic hazard. PCR screening provided a definitive diagnosis of psittacosis, and subsequent ompA gene analysis could be helpful for better understanding the epidemiology of the C. psittaci genotypes. To the best of our knowledge, this is the first report of the incidence of C. psittaci in parrots in Poland.

The occurrence of Chlamydia spp. in pigs with and without clinical disease

Background

Within the genera Chlamydia, the development of refined diagnostic techniques has allowed the identification of four species that are capable of infecting pigs. The epidemiology, clinical, and zoonotic impacts of these species are however largely unknown. The study aimed to investigate the presence of Chlamydia spp. in the intestines of growing pigs and in conjunctival swabs from finisher pigs, and relate the findings to clinical signs.

Results

By histology, 20 of 48 pigs had intestinal lesions that may be consistent with chlamydial infection. By PCR, forty-six of the pigs were positive whereas two samples were inhibited. Sequencing of 19 DNA extracts identified these as Chlamydia suis. By immunohistochemistry, 32 of 44 samples were positive and a significant relationship was detected between macroscopically visible intestinal lesions and a high degree of infection. By real-time PCR, a significant difference was detected between pigs with and without conjunctivitis when a Ct value of 36 was employed but not when a Ct value of 38 was employed.

Conclusions

Chlamydia suis was demonstrated in most samples and overall, no correlation to clinical signs was detected. However, a correlation was noted between samples with a high degree of infection and the presence of clinical signs. It is possible, that the intensive pig production systems studied might predispose for the transmission and maintenance of the infection thus increasing the infectious load and the risk for disease in the pig.

A survey of the transmission of infectious diseases/infections between wild and domestic ungulates in Europe

The domestic animals/wildlife interface is becoming a global issue of growing interest. However, despite studies on wildlife diseases being in expansion, the epidemiological role of wild animals in the transmission of infectious diseases remains unclear most of the time. Multiple diseases affecting livestock have already been identified in wildlife, especially in wild ungulates. The first objective of this paper was to establish a list of infections already reported in European wild ungulates. For each disease/infection, three additional materials develop examples already published, specifying the epidemiological role of the species as assigned by the authors. Furthermore, risk factors associated with interactions between wild and domestic animals and regarding emerging infectious diseases are summarized. Finally, the wildlife surveillance measures implemented in different European countries are presented. New research areas are proposed in order to provide efficient tools to prevent the transmission of diseases between wild ungulates and livestock.

Chlamydiaceae infections in pig

Chlamydiaceae are Gram-negative obligate intracellular bacteria. They are responsible for a broad range of diseases in animals and humans. In pigs, Chlamydia suis, Chlamydia abortus, Chlamydia pecorum and Chlamydia psittaci have been isolated. Chlamydiaceae infections in pigs are associated with different pathologies such as conjunctivitis, pneumonia, pericarditis, polyarthritis, polyserositis, pseudo-membranous or necrotizing enteritis, periparturient dysgalactiae syndrome, vaginal discharge, return to oestrus, abortion, mummification, delivery of weak piglets, increased perinatal and neonatal mortality and inferior semen quality, orchitis, epididymitis and urethritis in boars. However, Chlamydiaceae are still considered as non-important pathogens because reports of porcine chlamydiosis are rare. Furthermore, Chlamydiaceae infections are often unnoticed because tests for Chlamydiaceae are not routinely performed in all veterinary diagnostic laboratories and Chlamydiaceae are often found in association with other pathogens, which are sometimes more easily to detect. However, recent studies have demonstrated that Chlamydiaceae infections in breeding sows, boars and piglets occur more often than thought and are economically important. This paper presents an overview on: the taxonomy of Chlamydiaceae occurring in pigs, diagnostic considerations, epidemiology and pathology of infections with Chlamydiaceae in pigs, public health significance and finally on prevention and treatment of Chlamydiaceae infections in pigs.

High prevalence of antibodies against Chlamydiaceae and Chlamydophila abortus in wild ungulates using two "in house" blocking-ELISA tests

Few data are available on the prevalence and relevance of chlamydiae in wild mammals, and even fewer studies have been conducted to determine the prevalence of Chlamydophila abortus in wildlife hosts, most probably due to the absence of suitable species-specific serological assays for testing sera from wild animals. In light of this, we have developed two in-house blocking-ELISA tests for detection of antibodies against Chlamydiaceae and C. abortus in wild ungulates, and analyzed the relationship between geographical and biological factors and the prevalence of antibodies against Chlamydiaceae and C. abortus in 434 wild ungulates from Spain, including sera from European wild boar, Red deer, Fallow deer, Roe deer, Mouflon, Barbary sheep, Southern chamois, and Iberian ibex. Serology revealed that 41.7+/-4% of the sera were positive for the b-ELISA-LPS (Chlamydiaceae-specific) and 18.9+/-3% for the b-ELISA-rPOMP (C. abortus-specific). Antibodies against Chlamydiaceae lipopolysaccharide (LPS) were detected in sera from all eight ungulate species, the prevalence ranging from 23 to 60%. Iberian ibex was the only wild ungulate not showing seropositivity to the C. abortus specific polymorphic outer membrane protein (POMP). The prevalence of anti-POMP antibodies in the other seven wild ungulate species ranged from 7 to 40%. While significant seroprevalence differences were detected among species and among sampling regions, no effect of age and sex was observed. The high prevalence levels found should be considered with regards to livestock and human health, and warrant further research.

Recent developments in the laboratory diagnosis of chlamydial infections

There are two main approaches to diagnosing infections by Chlamydia and Chlamydophila spp. in mammals and birds. The first involves the direct detection of the agent in tissue or swab samples, while the second involves the serological screening of blood samples for the presence of anti-chlamydial antibodies. Ultimately, the test that is used is dependent on the types of samples that are submitted to the diagnostic laboratory for analysis. The present paper gives an overview on methodologies and technologies used currently in diagnosis of chlamydial infections with emphasis on recently developed tests. The performance characteristics of individual methods, such as the detection of antigen in smears and in pathological samples, the isolation of the pathogen, various antibody detection tests and DNA-based methods utilising conventional and real-time PCR, as well as DNA microarray technology are assessed, and specific advantages and drawbacks are discussed. Further, a combination of a specific real-time PCR assay and a microarray test for chlamydiae is proposed as an alternative reference standard to isolation by cell culture.

Transcriptional response patterns of Chlamydophila psittaci in different in vitro models of persistent infection

The obligatory intracellular bacterium Chlamydophila psittaci is the causative agent of psittacosis in birds and humans. The capability of this zoonotic pathogen to develop a persistent phase is likely to play a role in chronicity of infections, as well as in failure of antibiotic therapy and immunoprophylaxis. To elucidate three different in vitro models for transition of C. psittaci to persistence (iron depletion, penicillin G treatment, and gamma interferon [IFN-gamma] exposure), a set of 27 genes was examined by mRNA expression analysis using quantitative real-time PCR. While the phenotypical characteristics were the same as in other chlamydiae, i.e., aberrant morphology of reticulate bodies, loss of cultivability, and rescue of infectivity upon removal of inducers, the transcriptional response of C. psittaci to persistence-inducing factors included several new and distinctive features. Consistent downregulation of membrane proteins, chlamydial sigma factors, cell division protein, and reticulate body-elementary body differentiation proteins from 24 h postinfection onward proved to be a general feature of C. psittaci persistence. However, other genes displayed considerable variations in response patterns from one model to another, which suggests that there is no persistence model per se. In contrast to results for Chlamydia trachomatis, late shutdown of essential genes in C. psittaci was more comprehensive with IFN-gamma-induced persistence, which is probably due to the absence of a functional tryptophan synthesis operon.

Detection of chlamydiae in boar semen and genital tracts

Chlamydiae cause abortion and reproductive disorders in sows. Although organisms can infect the male genital tract, little is known about the disease situation in boars. Hence, we examined the prevalence of chlamydial infection in semen and genital tracts of boars. Samples collected from Swiss boars (group A: n=42), and boars from Germany (group B: n=39) were examined by bacteriology, LPS-ELISA, immunohistochemistry (IHC) and polymerase chain reaction (PCR). The latter methodology involved use of three PCR assays including 16Sig rDNA, IGS-S (intergenic spacer 16S/23S-Short) and IGS-L (intergenic spacer 16S/23S-Long) PCR for comparison methods. PCR sensitivity and the presence of potential PCR inhibitors were determined by spiking semen with Chlamydophila (Cp.) abortus DNA. Detection limits of the 16Sig and IGS-S PCR were 10 templates, while the IGS-L PCR was less sensitive (100 templates). Of 25 semen samples that were collected from group A, one semen sample was positive for Cp. psittaci and two were positive for Chlamydia-like organisms by 16Sig PCR. Screening of sera from Swiss boars revealed three animals with positive reactions in the LPS-ELISA, although we failed to detect chlamydiae within organs of these or sera-negative animals by IHC or IGS-S PCR. In group B, 10 ejaculates were positive for Chlamydia (C.) suis and two were positive for Chlamydia-like organisms by 16S PCR. The identification of DNA from Chlamydia-like organisms in semen from both groups of boars was surprising and a role for these bacteria in reproductive diseases requires further assessment. In conclusion, the prevalence of chlamydial infection was low in group A animals indicating that venereal transmission may not be significant for Chlamydia-associated reproductive diseases in pigs, although rare cases may occur.

Chlamydiae in oviducts and uteri of repeat breeder pigs

Chlamydial infections of the genital organs cause reproductive failure in female pigs, and the uterus is recognized a target tissue for an infection. In contrast, information on the effect of chlamydiae on the porcine oviduct is patchily and inconclusive, although the bacteria are known to cause severe tubal defects in humans and laboratory animals. The aim of this study was to examine the segments ampulla (A), isthmus (I) and utero-tubal junction of the left (n=20) or both (n=22) oviducts, and uteri (U) from 42 culled repeat breeder pigs for chlamydiae using ompA-PCR, partial ompA gene sequencing, immunohistochemistry (IHC) and microscopy of tissue specimens for histopathology. As revealed by PCR, among a total of 26 chlamydia-positive females, 19 were tested positive in one or more segments of one or both oviducts, 14 were found positive in the uterus, and concomitant infections of both organs were observed in 7 of them. Sequencing of 33 PCR products revealed the following chlamydial species: Chlamydophila (Cp.) psittaci (n=18), Cp. abortus (n=2), Chlamydia (C.) suis (n=10), and C. trachomatis (n=3). Immunopositive staining was observed within the surface epithelium (in A, I, U), stromal tissue (in I, U) and muscular layer (in A, I, U). A total of 24 females had inflamed oviductal segments (in A and/or I) and 36 inflamed uteri. However, there was no relationship between histopathology and results of PCR or IHC. In conclusion, chlamydiae were found to infect oviducts and uteri of pigs. Further studies are required to clarify whether chlamydial infection causes specific histopathology and alters tubal function.

Prevalence of chlamydiae in boars and semen used for artificial insemination

Although there are indications for venereal transmission of chlamydiae in pigs, direct diagnostic evidence on the presence of these bacteria in boars and boar semen in particular is still incomplete. We investigated boars from two studs (A, B) in semen (A: n = 174; B: n = 100) and faeces (A: n = 174; B: n = 24) for chlamydiae using ompA-PCR and partial ompA gene sequencing. Additionally, blood serum was examined for chlamydial antibodies using an indirect ELISA (A: n = 171; B: n = 62). Chlamydiae were found in 9 (5.2%) and 24 (24.0%) semen specimens, and in 71 (40.1%) and 2 (8.3%) faecal samples from boars of stud A and B, respectively. Regarding individual chlamydial species, Chlamydophila psittaci and Chlamydia suis were identified most frequently, with the former predominating in semen (in 23 out of 33 positive samples) and the latter in faeces (68/73). In contrast, Chlamydophila pecorum was found only sporadically. Chlamydial antibodies were detected in 80 (46.8%) and 6 (9.7%) boars of stud A and B, respectively. No correlation was observed between the data from serology and PCR of semen or faeces in either of the studs. In conclusion, detection of chlamydiae in semen of boars suggests a potential for venereal transmission. Whether the high overall prevalence of chlamydial infections reflects a general situation in boars needs to be investigated. Serological testing failed to identify boars shedding chlamydiae in their semen.