Search Results (46)

Wild birds are increasingly recognized as contributors to the circulation and environmental dissemination of zoonotic pathogens, yet data from Greece remain limited, particularly for raptors, corvids, and water birds. This study investigated selected parasitic, mycotic, and bacterial pathogens of public health relevance in free-living wild birds originating from various regions of Greece and admitted to two animal health care facilities. Between November 2023 and May 2025, cloacal swabs from 212 injured or sick birds were analyzed using quantitative PCR for Cryptococcus spp., Chlamydia psittaci, Giardia duodenalis, Cryptosporidium spp., and Mycobacterium avium. At least one pathogen was detected in 37 samples (17.5%), with Cryptococcus spp. being the most frequent agent (11.8%), followed by C. psittaci (3.8%), G. duodenalis (0.9%), and Cryptosporidium spp. (0.9%). M. avium was not detected. Pathogen occurrence varied by bird category, genus, and region, and was associated with health status. To the best of our knowledge, this study provides the first molecular evidence worldwide of G. duodenalis in Ardea spp., Cryptosporidium spp. in Asio otus, and C. psittaci in Botaurus stellaris and Plegadis falcinellus. These findings highlight wild birds as potential zoonotic reservoirs and support the implementation of One Health–oriented surveillance programs. Full article

Wild birds are relevant reservoirs and sentinels for zoonotic pathogens such as Chlamydia psittaci and West Nile virus (WNV), both of which can affect animal and public health. Wildlife rehabilitation centers (WRCs) offer unique opportunities for passive surveillance of emerging and re-emerging infectious diseases, particularly in urban and peri-urban settings. From 2013 to 2022, a total of 1024 bird samples were collected upon admission to WRCs in the Community of Madrid, Spain. Oropharyngeal and cloacal swabs, as well as tissue samples, were tested using real-time PCR targeting the ompA gene of C. psittaci and the 3’NC region of WNV. One sample tested positive for C. psittaci by real-time PCR in 2021, yielding a positivity rate of 0.22% (95% CI: 0.01–1.19). No positive cases were detected during the remaining years of the study. All samples tested negative for WNV over the nine-year period. The low detection rate suggests limited circulation of these pathogens among wild birds in central Spain, though it may partly reflect the variability inherent to passive surveillance and sample-type heterogeneity. However, continued surveillance is warranted, especially in high-risk avian species and personnel occupationally exposed in avian rehabilitation facilities using expanded sample sizes and complementary diagnostic tools. Extending monitoring beyond the typical vector season and increasing testing of sensitive tissues, particularly for WNV, may further enhance detection sensitivity and strengthen early-warning capacity. These efforts are essential to improve early detection and risk assessment within a One Health framework. Full article

Avian chlamydiosis, primarily caused by Chlamydia psittaci (C. psittaci), poses significant threats to poultry and avian trade. Emerging species such as Chlamydia gallinacea (C. gallinacea), Chlamydia avium (C. avium), and Chlamydia ibidis (C. ibidis) have recently been detected in birds. However, the prevalence and genetic diversity of avian chlamydia in birds within Guangxi remain unknown. In this study, 1744 samples collected from apparently healthy birds were screened, revealing an overall positivity rate of 28.20% (95% CI, 27.58–28.90%, 492/1744) for avian chlamydia. Among poultry, pigeons had the highest positivity rate at 62.30% (95% CI, 55.37–68.69%, 152/244), followed by chickens at 25.05% (95% CI, 21.25–29.23%, 128/511), geese at 18.12% (95% CI, 12.93–24.82%, 29/160), and ducks at 14.14% (95% CI, 11.57–17.26%, 82/580). Additionally, pet and wild birds exhibited positivity rates of 40.35% (95% CI, 34.20–46.83%, 92/228) and 42.86% (95% CI, 24.52–61.83%, 9/21), respectively. Phylogenetic analysis based on the outer-membrane protein A gene indicated that chicken samples belonged to genotypes B of C. psittaci and C. gallinacea. In ducks, genotypes A and B of C. psittaci and C. gallinacea were identified, representing the first documented occurrence of C. psittaci genotypes B and C. gallinacea in ducks in China. The nucleotide sequences from goose samples were initially clustered into genotype A group, while those from pigeons were clustered within genotype B. Furthermore, positive samples from pet birds were classified into genotypes A and B, as well as the C. gallinacea group. Similarly, samples from wild birds were classified into genotypes A and B. These findings suggest that diverse avian chlamydia genotypes are circulating among bird populations in Guangxi, with an expanding host range indicating potential cross-species transmission. Moreover, certain strains derived from waterfowl were found to cluster with those linked to recent psittacosis outbreaks, highlighting the zoonotic potential of avian chlamydia. Therefore, sustained surveillance for avian chlamydia in bird populations and monitoring its genetic evolutionary characteristics are essential to decrease public health risks. Full article

Background/Objectives: Chlamydia (C.) psittaci is an avian respiratory pathogen that regularly infects budgerigars (Melopsittacus undulatus) and is a known zoonosis. This study aimed to evaluate the efficacy of a nucleoside-modified mRNA vaccine formulated in lipid nanoparticles (LNPs), either with (mRNA Galsomes) or without (mRNA LNPs) the glycolipid antigen α-Galactosylceramide, in protecting budgerigars against C. psittaci genotype A infection. Methods: Three groups of eight budgerigars received two intramuscular vaccinations with PBS, mRNA LNPs or mRNA Galsomes, and were subsequently challenged via aerosol with the C. psittaci genotype A strain 90/1051. Vaccine efficacy was assessed over 14 days post challenge by monitoring clinical signs, macroscopic and microscopic lesions, pathogen excretion and chlamydial burden in organs. Antibody levels were evaluated at baseline, after vaccination and post challenge. Results: Both mRNA LNPs and mRNA Galsomes induced significant serum antibody responses post booster. Vaccination significantly reduced clinical signs, chlamydial burden in the lungs and macroscopic lesions in conjunctiva, conchae, lungs and thoracic airsacs, compared to controls. Additionally, mRNA Galsomes-treated birds showed a significantly reduced lung inflammation and fewer macroscopic lesions in abdominal airsacs and liver, compared to non-vaccinated animals. These animals also experienced a significantly lower chlamydial burden in the spleen, fewer clinical signs at day 11 and fewer fecal shedding at day 14 post challenge, compared to mRNA LNP-treated animals. Conclusions: This study demonstrated that mRNA vaccination confers partial protection against C. psittaci in budgerigars, with mRNA Galsomes appearing to provide enhanced efficacy. However, the absence of species-specific reagents for assessing cellular immunity in Psittaciformes limits a comprehensive understanding of vaccine-induced protection. The development of psittacine-specific T cell markers and cytokine assays is necessary to further elucidate immune mechanisms and optimize vaccine formulations. Full article

Chlamydia psittaci is a bacterium that infects several species of birds and mammals. It is the causal agent of avian chlamydiosis and psittacosis in humans and it is globally distributed. Chlamydia psittaci is one of the main zoonotic pathogens transmitted by birds. In Argentina, there has been limited research on the prevalence and genetic variability of C. psittaci. The aim of this study was to detect and genotype C. psittaci using molecular techniques in birds living in Buenos Aires City, Argentina, during the period 2012–2015. A descriptive, observational, retrospective and cross-sectional study was carried out. A total of 983 bird samples submitted for diagnosis of avian chlamydiosis were analyzed. The frequency of C. psittaci was 12.54% and 7.89% in Psittaciformes and Columbiformes, respectively. A 348 bp region of the ompA gene was sequenced in positive samples. Molecular genotyping was performed through a Bayesian phylogenetic analysis. Of the 983 bird samples, 83 were positive for C. psittaci and 44 could be sequenced. The genotypes found were A, B, and E. Despite the high levels of host specificity, we found six psittacids with genotype B and one pigeon with genotype A, reflecting the affiliative interaction between Psittaciformes and Columbiformes. This study represents the first survey reporting the presence of C. psittaci in birds within the largest and most populous city in Argentina. Full article

Chlamydiosis, caused by Chlamydia psittaci is a bacterial infection found in at least 465 species of birds worldwide. It is highly contagious among birds and can spread to humans. In birds, the disease can manifest itself in acute, subacute, and chronic forms with signs including anorexia, diarrhea, lethargy, weight loss, or, occasionally, mucopurulent or serous oculonasal discharge. This article describes an outbreak of chlamydiosis that occurred in a commercial psittacine breeding aviary in 2021 in Buenos Aires province, Argentina. In total, 16 juvenile blue-fronted parrots, more than 60 blue-fronted parrot chicks, and 2 adult macaws died during the outbreak. In all cases, clinical signs were weight loss, diarrhea, yellowish green excrement, and respiratory distress. The necropsy of four juvenile blue-fronted parrots, two blue-fronted parrot chicks, and two adult macaws revealed cachexia, hepatomegaly, splenomegaly, splenic petechial hemorrhages, ascites, pulmonary edema, and hydropericardium. Histologically, multifocal lymphoplasmacytic and heterophilic airsaculitis, multifocal lymphoplasmacytic and necrotizing hepatitis with intracytoplasmic elementary bodies, multifocal necro-heterophilic hepatitis, multifocal lymphoplasmacytic nephritis, and diffuse heterophilic pneumonia were found. A presumptive diagnosis was established based on gross and microscopic lesions, and it was confirmed using immunohistochemistry and polymerase chain reactions. The sequencing and phylogenetic analysis of the ompA gene revealed genotype A and B of Chlamydia psittaci. Full article

Birds are known to be carriers of ticks infected by tick-borne pathogens, including bacteria. However, not many studies have been carried out on avian tissues to detect these agents. The aim of the present survey was to investigate, using PCR, the presence of Anaplasma phagocytophilum, Bartonella spp., Borrelia burgdorferi sensu lato, Chlamydia psittaci, Coxiella burnetii, Ehrlichia canis, Francisella tularensis, and Rickettsia spp. in the spleens collected from 300 wild birds of different orders and species from Central Italy. A total of 53 (17.67%) samples were PCR positive for at least one investigated pathogen. One (0.33%) bird was positive for Bartonella spp., five (1.67%) birds were positive for C. burnetii, eleven (3.67%) for B. burgdorferi s.l., and thirty-six (12%) for C. psittaci. No coinfection was detected. All samples were negative for A. phagocytophilum, E. canis, F. tularensis, and Rickettsia spp. The findings showed that wild birds may harbor different zoonotic tick-borne bacteria; therefore, they can contribute to the diffusion of these agents. Full article

Serology routinely serves as a diagnostic tool to confirm Chlamydia infections in humans. Particularly in delayed settings, such as post-outbreak scenarios where the acute phase of infection has subsided, serology is invaluable. Multiple studies, nonetheless, indicate deficiencies in specificity and sensitivity of current chlamydial antibody detection assays. Incorporation of multiple antigens per target is known to improve the accuracy of chlamydial serological assays. We, therefore, used the recomLine test (Mikrogen diagnostics) on serological samples of two cohorts, as it is the only commercially available test allowing detection of antibodies against three human pathogenic Chlamydia species (C. trachomatis, C. pneumoniae and C. psittaci) using multiple antigens per target. The first cohort (n = 156; samples collected between 2008 and 2022 during a C. trachomatis screening initiative) comprised women from the Netherlands (NL) with past exposure to C. trachomatis, while the second cohort (n = 44; samples collected in 2018 in a health examination survey) consisted of Belgian citizens (BE) with occupational or recreational exposure to chickens, representing a risk population for C. psittaci. The test indicated a statistically equivalent C. pneumoniae seroprevalence in both cohorts (39.10% in NL and 34.09% in BE; p = 0.337). As expected C. trachomatis seroprevalence was significantly higher (p < 0.001) in the Dutch cohort (48.72%), as compared to the Belgian cohort (4.55%). Lastly, C. psittaci seroprevalence did not significantly differ between the two groups (2.27% in BE and 1.92% in NL; p = 0.633), even though a higher prevalence was expected for the Belgian cohort. This prompts us to question whether the Belgian cohort truly constituted a C. psittaci risk population or whether the recomLine test is susceptible to cross-reaction of species-specific antibodies, thereby increasing C. psittaci prevalence in the Dutch cohort. We advocate for the development of affordable, highly sensitive antibody detection assays that can effectively distinguish between chlamydial species, addressing the increasing demand for enhanced serological testing methodologies. Full article

Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma. The disease is very heterogeneous, with distinct genetic alterations in subtypes. The WHO 2022 5th edition classification identifies several minor groups of large B-cell lymphoma where the pathogenetic role of viruses (like EBV and HHV-8) is identified. Still, most cases fall into the group of DLBCL not otherwise specified (NOS). No review focuses only on this specific lymphoma type in the literature. The pathogenesis of this entity is still not fully understood, but several viruses and bacteria may have a role in the development of the disease. The authors review critical pathogenetic events in the development of DLBCL (NOS) and summarize the data available on several pathogenetic viruses and bacteria that have a proven or may have a potential role in the development of this lymphoma type. The possible role of B-cell receptor signaling in the microenvironment is also discussed. The causative role of the Epstein–Barr virus (EBV), human herpesvirus-8 (HHV-8), Hepatitis C virus (HCV), human immunodeficiency virus (HIV), Hepatitis B virus (HBV), and other viruses are explored. Bacterial infections, such as Helicobacter pylori, Campylobacter jejuni, Chlamydia psittaci, Borrelia burgdorferi, and other bacteria, are also reviewed. Full article

The members of the Chlamydiaceae family are important pathogens that infect a wide range of vertebrate hosts, including humans. Among them, Chlamydia psittaci, historically considered as an avian agent, has recently been identified in livestock, primarily sheep and cattle, but also in horses, with the infection being linked to reproductive disorders, such as abortion, absorption of embryos, stillbirth, and the birth of weak foals. Much less is known about chlamydial infections in the Sardinian equine population. This study aimed to identify the chlamydial diversity in genital samples from asymptomatic Sardinian horses. However, some horses had a previous history of reproductive disorders, i.e., abortion and infertility. A total of 60 horses (39 mares and 21 stallions) were opportunistically recruited from 17 equine farms in central-northern Sardinia. Vaginal and uterine swabs from mares and urethral swabs and seminal fluid from stallions were sampled for the presence of chlamydial DNA. Samples from environments where the horses lived were also tested for the detection of Chlamydia spp. Eight vaginal swabs (8/39; 20%), two uterine swabs (2/27; 7%), two seminal fluid samples (2/20; 10%), and one urethral swab (1/21; 4.7%) were found to be positive for Chlamydia spp. by PCR analysis. In addition, results from environmental samples showed the presence of Chlamydia spp. in three environmental swabs (3/8; 37.5%) and five water samples (5/16; 31.2%). Sequencing results revealed that strains here identified were 99–100% similar to members belonging to the Chlamydiaceae family, including C. abortus, C. psittaci, and uncultured Chlamydia genotypes. ompA species-specific PCR performed on samples was found to be positive after 16S rRNA amplification gave positive results for C. psittaci. These results reveal the first presence of C. psittaci in the genital tract of horses and in the environment in Sardinia and indicate that this pathogen could be the prevailing cause of infertility and abortion in the tested equines. However, these findings need further proof and highlight the importance of adopting a ‘One Health’ approach to control the presence of this zoonotic bacteria in domestic animals in order to understand its impact on people exposed to the infection risk. Full article

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). Full article

Native and exotic avian species can act as reservoirs of pathogens, including bacteria and viruses, with conservation and public health implications. A retrospective study on the diagnosis and frequency of diseases in wild and exotic avian species was conducted. The occurrence of particular diseases was associated with the type of captivity or the bird’s origin. The investigation included macroscopic and microscopic descriptions and the molecular determination of the causative agent(s). Additional immunohistochemical (IHC) analysis, PCR, and genetic sequencing were conducted. A total of 243 cases were compiled for the study, mainly consisting of native wild species (39.1%) obtained from illegal trade. Primary infectious diseases, mainly parasitic (18.1%) and viral (17.7%), were the most common, although coinfections were substantial (18.1%) in birds rescued from trafficking. Fractures and neoplasms accounted for 3.7% and 3.3% of the cases, respectively. Parasitic and viral diseases were the most common in both exotic and wild birds. Chlamydia psittaci, a lethal and zoonotic bacterium, was an important cause of death, especially in native Psittaciformes. The recent detection of Psittacid alphaherpesvirus 5 (PsAHV 5) in exotic psittacines and the diagnosis of coinfections in trafficked birds highlight the importance of monitoring avian health to control potential pathogens that may endanger conservation efforts. Full article

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. Full article

Chlamydia psittaci is an important zoonotic pathogen. Although primarily a pathogen of birds, from which infection can spillover into humans and other mammalian hosts, the importance of C. psittaci as a cause of equine reproductive loss and the risk of infection to humans in contact with infected horses are increasingly being recognised in Australia and elsewhere. Despite the risks to both human and equine health, C. psittaci infection in horses is incompletely understood. This study aimed to update and summarise cases of equine psittacosis in Australia in the period 2018–2022, thus addressing a knowledge gap relating to recent cases in this country. These cases were identified from the examination of records held by state and federal veterinary authorities and from a review of published cases. A total of 31 cases were identified. Spatial and temporal trends were identified, with cases being more prevalent in winter and spring and geographically restricted to Victoria and New South Wales. The results show that cases of equine reproductive loss due to C. psittaci are consistent and ongoing and demonstrate the importance of routinely considering C. psittaci in diagnostic investigations. The need for ongoing study to better understand this important zoonotic pathogen is evident. Full article

Chlamydia psittaci (C. psittaci), a zoonotic pathogen, poses a potential threat to public health security and the development of animal husbandry. Vaccine-based preventative measures for infectious diseases have a promising landscape. DNA vaccines, with many advantages, have become one of the dominant candidate strategies in preventing and controlling the chlamydial infection. Our previous study showed that CPSIT_p7 protein is an effective candidate for a vaccine against C. psittaci. Thus, this study evaluated the protective immunity of pcDNA3.1(+)/CPSIT_p7 against C. psittaci infection in BALB/c mice. We found that pcDNA3.1(+)/CPSIT_p7 can induce strong humoral and cellular immune responses. The IFN-γ and IL-6 levels in the infected lungs of mice immunized with pcDNA3.1(+)/CPSIT_p7 reduced substantially. In addition, the pcDNA3.1(+)/CPSIT_p7 vaccine diminished pulmonary pathological lesions and reduced the C. psittaci load in the lungs of infected mice. It is worth noting that pcDNA3.1(+)/CPSIT_p7 suppressed C. psittaci dissemination in BALB/c mice. In a word, these results demonstrate that the pcDNA3.1(+)/CPSIT_p7 DNA vaccine has good immunogenicity and immunity protection effectiveness against C. psittaci infection in BALB/c mice, especially pulmonary infection, and provides essential practical experience and insights for the development of a DNA vaccine against chlamydial infection. Full article