Search Results (1,035)

During 2022–2024, a highly pathogenic avian influenza virus (HPAIV) H5N1 strain, designated A/Seagull/Hebei/qhd6/2024 (H5N1), was isolated from migratory birds in Beidaihe National Wetland Park, North China. Phylogenetic analyses revealed that its hemagglutinin (HA) gene belongs to the 2.3.4.4b clade, while the neuraminidase (NA) gene and internal genes clustered with strains originating from multiple continents, consistent with a transcontinental reassortment event. The virus also exhibited 90.1–98.1% nucleotide homology with human-derived H5N1 isolates. Molecular characterization identified key virulence-associated mutations, including the classic HPAIV HA cleavage site, HA-T160A (associated with enhanced human receptor-binding capacity), and NA-I117T (potentially linked to drug resistance). BALB/c mouse infection experiments confirmed systemic replication and high pathogenicity of strain qhd6, with a 50% lethal dose (LD50) of 0.95 log₁₀EID₅₀/mL. Antigenic analysis revealed good cross-reactivity with the widely used H5-Re14 vaccine strain. This study reports the identification, in Beidaihe National Wetland Park, of an HPAIV H5N1 strain whose genetic characteristics suggest intercontinental reassortment and indicate cross-species transmission risk. It clarifies the genetic characteristics and pathogenicity of this strain, providing an important theoretical and practical basis for precise surveillance, risk early warning, and comprehensive prevention and control of AIV at migratory bird stopover sites in North China. Full article

Avian metapneumovirus (aMPV) is a major respiratory pathogen of poultry with a significant economic impact; however, its epidemiology at the wildlife–poultry interface remains poorly understood, particularly within Afro–Eurasian migratory systems. This cross-sectional study (December 2024–April 2026) investigated aMPV occurrence in wild birds across eleven Egyptian governorates representing key ecological zones along major migratory flyways. A total of 1280 samples were collected from 800 wild birds representing migratory waterfowl and synanthropic species, including 800 oropharyngeal swabs tested by real-time RT-qPCR for aMPV subtypes A and B and 480 serum samples analyzed using indirect ELISA. aMPV RNA was detected in 28/800 samples (3.5%), with all positives identified as subtype B and confined to the Nile Delta, Middle Egypt, and Canal Region. In contrast, serological analysis revealed a high seroprevalence of 58.3% (280/480), indicating widespread prior exposure with significant spatial and species-level variation (p < 0.05). The marked disparity between low molecular detection and high seroprevalence supports transient infection with cumulative exposure. The exclusive detection of subtype B may reflect epidemiological connectivity between poultry and wild bird populations within shared ecological interfaces; however, the directionality of transmission and the possibility of independent wildlife maintenance could not be determined within the scope of the present cross-sectional study. Future studies incorporating whole-genome sequencing, longitudinal surveillance, and broader flyway-scale sampling are needed to resolve transmission pathways and distinguish field strains from potential vaccine-derived viruses within wildlife–poultry interfaces. Full article

Karyotypic diversification in birds is often masked by overall chromosomal conservation, yet the mechanisms driving lineage-specific variation remain poorly understood. Here, we demonstrate that genome evolution in Rallidae is shaped by dynamic, independent trajectories of chromosomal reorganization, despite the retention of general avian architectural features. By integrating cytogenetic and molecular mapping data from two Neotropical species, Fulica rufifrons Philippi & Landbeck, 1861 (Red-fronted Coot) and Aramides ypecaha Vieillot, 1819 (Giant Wood Rail), we show that repetitive DNA expansion and heterochromatinization contribute to karyotype variability and sex chromosome differentiation. The contrasting structure and heterochromatic composition of the W chromosome between these species reveal that sex chromosomes evolve rapidly and independently, driven by lineage-specific accumulation of repetitive elements. Moreover, the variation in microsatellite distribution, especially the distinct localization of motifs on macro- and microchromosomes, underscores the independent and dynamic evolution of repetitive sequences. Our findings collectively indicate that chromosomal rearrangements, along with the amplification and redistribution of repetitive DNA, are contributing factors of genomic diversification in Rallidae, offering new insights into the mechanisms underlying karyotype evolution and sex chromosome differentiation in birds. Full article

Pigs play a key role in the ecology of influenza A viruses (IAVs), particularly in avian influenza (AI)-endemic regions where co-circulation of viruses from different hosts increases reassortment risk. Between September 2023 and August 2024, we surveyed pigs from Lebanon and Egypt to study IAV ecology in AI-endemic countries. Nasal swabs and sera were collected and tested using real-time RT-PCR and hemagglutination inhibition assays against avian, swine, and human seasonal IAVs. Molecular analyses identified IAV-infections in both countries, including human H1 and avian H5 subtypes, which may reflect potential cross-species transmission from humans and birds. Serologic analyses revealed prior exposure to avian, swine, and human IAVs. Avian virus seropositivity reached 4.6% (H5N1) and 15.2% (H9N2) in Egypt and 8.6% (H5N1) and 4.3% (H9N2) in Lebanon. Antibodies against human H1N1 and H3N2 were prevalent in both countries. Serologic evidence exceeded molecular detection, indicating frequent past or transient infections not captured by PCR alone. Antibody responses were significantly associated with host-level factors such as housing type, age, shaping exposure risk. These findings demonstrate repeated multisource exposure of pigs to genetically distinct IAVs in AI–endemic countries, supporting the need for integrated virologic and serologic surveillance within a One Health framework. Full article

Tropical forest restoration has increased in the past decades, with possible advancements given the UN declaration of the “Decade of Ecosystem Restoration”. However, robust assessments to compare ecosystem functions among restored forest stages are essential. We evaluated 13 actively restored forest stands ranging from 3 to 21 years of age and compared measures of forest biodiversity, structure, and ecosystem function to four 70+ year old “reference” stands that serve as restoration “targets” in the study region of the Premontane wet forest of Costa Rica. The restored stands were planted with an average of 13 tree species on abandoned pastures that were fallow for at least two years. Sixteen tree-stand attributes and six ecosystem function estimates were assessed, including: annual biomass (C) accumulation, N-fixation potential, threatened species conservation, and the provision of avian frugivore forage, insect habitat, and insect pollination. Using Principal Component Analysis, linear modeling, and Mahalanobis distance analyses, we learned that planting a diversity of tree species sets the stage for forest recovery at early restoration ages, with an inflection point at 15 years towards older reference forest characteristics and functions. Given that all restoration ages provided tree diversity and some level of ecosystem functions, the value of all restored stands in the landscape is notable. The assessment methods are easily employed, thereby providing an accessible tool to restoration practitioners. Full article

(1) Background: Diclofenac sodium is a drug with reported developmental toxicity in several non-mammalian and mammalian models. This study aims to evaluate the stage-dependent embryolethality of diclofenac sodium according to developmental stage using the chicken (Gallus gallus domesticus) embryo in ovo model, a system widely used in veterinary and avian developmental toxicology screening. The study focuses specifically on quantitatively determining the “critical sensitivity windows” between the early (day 7) and late (day 14) embryonic stages. (2) Methods: Fertilized chicken eggs (Gallus gallus domesticus) were exposed to different doses (3.125–50 mg/kg) of diclofenac sodium, and mortality rates were analyzed. (3) Results: The data indicated that diclofenac toxicity is highly dependent on the developmental stage (p = 0.002). While the LD50 value for the early stage (day 7) was calculated as 20.67 mg/kg, (95% CI 6.79–860.87 mg/kg; wide interval reflecting low precision and steep response), embryos at the late stage (day 14) were found to be more resistant, with an LD50 value of 32.16 mg/kg (95% CI 27.77–37.90 mg/kg). The calculated Potency Ratio of 1.55 indicates that 7-day-old embryos are more sensitive to diclofenac. (4) Conclusions: This study provides model-specific preliminary quantitative data on the stage-dependent embryo mortality profile of diclofenac sodium in chicken embryos. The higher mortality observed on day 7 is consistent with a window of susceptibility during early organogenesis that may be associated with immature detoxification pathways (e.g., hepatic CYP450) and active organic anion transport (e.g., Oatp1d1) reported in other developmental models. However, these mechanisms were not directly measured here. These findings contribute to comparative developmental toxicology and the One Health-focused assessment of NSAID exposure in animal species, emphasizing the importance of considering “timing of exposure” in developmental toxicity assessments. Furthermore, no extrapolation to mammalian pregnancy or human clinical guidelines is implied. Full article

The high case fatality rate, cross-species transmission, and ongoing evolution of H5 avian influenza viruses pose an imminent threat of an influenza pandemic, particularly with the currently predominant clade 2.3.4.4b lineage. Existing seasonal influenza vaccines and licensed H5 vaccines provide limited cross-protection against H5 viruses, underscoring an urgent need for the development of broadly protective H5 vaccines. In this study, we analyzed all human-infected H5 hemagglutinin (HA) sequences using bioinformatics approaches and subsequently designed a novel H5 influenza vaccine through algorithm optimization. The predicted structure of this vaccine closely resembles that of the wild-type H5 HA trimer. In animal studies, the algorithm-optimized H5 mRNA vaccine not only induced high levels of neutralizing antibodies against multiple clade 2.3.4.4b H5 viruses but also elicited cross-neutralizing antibodies against clade 2.3.4.4 and clade 2.2.1 H5 viruses, as well as robust cellular immune responses. These findings highlight the potential of algorithm-based approaches in developing broadly protective vaccines against pandemic viruses and suggest that this vaccine candidate could serve as a strategic stockpile for preventing H5 influenza pandemics. Full article

Systems that farm non-typical (wild) species for human consumption are on the rise globally, in contrast to more typical livestock production. In some instances, wildlife farming may arguably help alleviate poverty, provide sustainable animal protein, and be a useful strategy for conservation through reducing wildlife poaching or breeding some animals on farms for reintroduction. However, it is unclear whether farming non-typical species within variable and often unregulated systems truly offers these benefits or outweighs the costs including animal welfare implications, public health concerns, and normalising or intensifying the consumption of wild animals. A previous study proposed a sentiocentric ethical decision-making framework for the farming of wild species. In the present study we invited academic ‘key informants’ with specialised knowledge about farming non-typical species to pilot the framework via an online survey using a species of their choice and requested their feedback on its strengths and weaknesses. Thirteen respondents applied ten different mammalian, reptilian, insect, and avian species to the framework, spanning all continents. Ultimately, the framework outcome for 11 appraisals was that the chosen species may be suitable for farming. However, erroneous responses were likely in places, and there was some uncertainty over definitions of framework terminology. We publish resultant amendments to the ethical framework to clarify meaning and suggest that it can be applied proactively or reactively by different stakeholders (e.g., governments, businesses, and NGOs). We reflect our informants’ views, acknowledging the need to solicit expertise from additional stakeholders (e.g., farmers) and the role of cultural significance and rural communities when considering farming non-typical species. Full article

Avian influenza (AI) remains a serious threat to poultry and public health worldwide due to its zoonotic nature and pandemic potential. This paper develops and analyzes a coupled system of nonlinear ordinary differential equations and an SEIR-SEIR model that describes the transmission dynamics of avian influenza in both human and bird populations. The model incorporates multiple transmission routes (bird-to-bird, bird-to-human, human-to-human), exposed/latent compartments in both hosts, disease-induced mortality, and demographic processes. From a mathematical perspective, we present a rigorous analysis of this eight-dimensional dynamical system. We prove positivity and boundedness of solutions in ${\mathbb{R}}_{+}^8$, characterize the equilibrium points, and derive the basic reproduction numbers $R_0^b$ and $R_0^h$ using the next-generation matrix method. Local asymptotic stability of the disease-free equilibrium is established via the Routh–Hurwitz criterion. A composite Lyapunov function is constructed to prove global asymptotic stability when both reproduction numbers are less than unity—a result that exploits the cascade structure of the system and provides a template for analyzing similar multi-host models. Sensitivity analysis using normalized forward sensitivity indices identifies critical parameters. In addition, we use neural network models to validate both models and provide error analysis. These results emphasize the crucial role of controlling cross-species transmission and improving recovery efforts, which have significant implications for the design of effective intervention and surveillance programs in the context of the One Health framework. Full article

Research increasingly identifies wild birds, particularly long-distance migratory species, as epidemiologically relevant hosts and vectors for tick-borne Borrelia species that pose risks to both avian and human health. This review contextualizes avian-associated Borrelia research historically and microbiologically, showing the role of avian hosts in the ecology of agents causing relapsing fever and Lyme borreliosis. We identify key publications that trace the evolution of Borrelia research—from early microscopic observations of spirochetes to the modern molecular and serological evidence. The review collects literature on the process by which Borrelia gained early scientific attention due to its characteristic morphology and elevated bloodstream concentrations during septicemic phases, which enabled early etiological links between the microbe and disease. It follows the recognition of avian spirochetosis caused by Borrelia anserina and charts the shift in focus after the discovery of Borrelia burgdorferi sensu lato (Subgen. novum recomm. Borreliella, Lyme-group Borrelia). Publications listed show that birds can transport infected human-parasitic ticks over long distances and, in certain bird species, selectively amplify Lyme-group Borrelia species, especially Borrelia garinii, which has the highest temperature tolerance and is thus potentially viable in avian hosts. The literature supports the role of birds in maintaining and disseminating Borrelia infections and infected ticks across continents. Full article

Background/Objectives: Pet birds are increasingly recognized as potential reservoirs of zoonotic and antimicrobial-resistant bacteria, raising concerns within the One Health framework. However, data on bacterial diversity and resistance profiles in clinically affected ornamental birds remain limited. Methods: This study, conducted over three years (November 2022–March 2026), included 198 pet birds presenting with digestive and respiratory disorders. From these birds, clinical samples were analyzed bacteriologically; resulting isolates were identified by MALDI-TOF mass spectrometry, and antimicrobial susceptibility assessed using the Kirby-Bauer disk diffusion method according to EUCAST and CLSI guidelines. Results: Bacterial growth was detected in 87.9% of cases, yielding 249 distinct isolates. Gram-positive cocci predominated (62.3%), led by Staphylococcus spp. (33.3%) and Enterococcus spp. (9.6%), while Escherichia coli (9.2%) was the primary Gram-negative species. At the genus level, Staphylococcus spp. demonstrated high susceptibility to amikacin (88.5%) but significant resistance to gentamicin (75.6%) and oxytetracycline (63.6%). In contrast, Escherichia spp. isolates were largely resistant, showing only 50% susceptibility to enrofloxacin and 40% to doxycycline, with resistance to tylosin reaching 90%. Overall, 57% of isolates were multidrug-resistant, with Staphylococcus spp. contributing most to this burden. Conclusions: These findings characterize clinically ill pet birds as significant carriers of multidrug-resistant bacteria, highlighting the need for routine diagnostics and improved antimicrobial stewardship in avian medicine. Full article

Ascaridia nymphii is a roundworm species affecting domestic avian species, initially described in 2015. One pen-reared, 4-year-old, female American Show Racer pigeon (Columba livia f. domestica) was submitted to the California Animal Health and Food Safety Laboratory System (CAHFS) Turlock branch, University of California–Davis, for postmortem examination and diagnostic work-up. Grossly, large numbers of ascarids were in the lumen of the proventriculus, gizzard, and duodenum, and a small number was present in the lumen of the trachea, esophagus, and crop. A focal, coiled adult nematode was embedded in the hepatic parenchyma. Ascarids were tan and measured approximately 3.5–4.5 cm in length. The liver was moderately enlarged, green-tinged, and had small, firm, and off-white scattered nodules. Microscopically, we observed multifocal to coalescing granulomas containing intralesional nematodes delineated by necrotic debris, multinucleated giant cells, eosinophilic and heterophilic inflammation, hemorrhage, and bacterial colonies in the liver. The genotypic characterization of the Ascaridia sp. in our case (GenBank database accession PX488893) shared 100% identity with A. nymphii isolated from the intestinal tract of a cockatiel (Nymphicus hollandicus) from Japan in 2015 (GenBank database accession LC057210.1) based on PCR and sequence analysis of an 815 bp segment of the 18S rRNA gene. This report describes the accidental A. nymphii infection, which caused severe gastrointestinal impaction and hepatic migration in a domestic pigeon. Full article

Avian haemosporidian parasites, especially Plasmodium juxtanucleare, Leucocytozoon caulleryi, and Leucocytozoon sabrazesi, represent major threats to poultry health and production. However, there is limited epidemiological information about these pathogens in domestic chickens in Southern China, which hinders effective disease prevention and control. The objective of this study was to conduct a cross-sectional survey to investigate the epidemiological characteristics of these three parasites in Guangxi and Hunan Provinces between June 2024 and December 2025. A total of 941 blood samples were collected from domestic chickens and analyzed using both nested PCR targeting the cytb gene and species-specific PCR assays targeting the coxI gene. The overall detection rate of haemosporidian infection was 25.40% (239/941). P. juxtanucleare was the most commonly detected species, with a detection rate of 23.59% (222/941), followed by L. caulleryi at 1.81% (17/941), while no L. sabrazesi infections were identified. Analysis of risk factors showed that chickens older than 90 days had significantly higher detection rates for both P. juxtanucleare and L. caulleryi compared to younger birds. Additionally, breed-specific differences were noted, with black-bone and partridge chickens showing higher susceptibility to P. juxtanucleare than three-yellow chickens. Genetic analysis of coxI sequences demonstrated high conservation among P. juxtanucleare isolates (99.7–100% similarity) and complete identity among L. caulleryi strains. Phylogenetic analysis confirmed that all sequences clustered with the corresponding reference strains from GenBank. This study presents an epidemiological evaluation of these three haemosporidian parasites in domestic chickens from Guangxi and Hunan Provinces, identifying P. juxtanucleare as a widespread pathogen and highlighting age and breed as important risk factors. These results emphasize the importance of ongoing monitoring and targeted control measures in the area. Full article

(1) Airborne fine particulate matter (PM_2.5) poses a growing threat to poultry production by impairing intestinal health, disturbing microbial balance, and reducing growth performance. Rosmarinic acid (RA), a natural polyphenol with antioxidant, anti-inflammatory, and gut microbiota-regulating properties, can effectively maintain intestinal homeostasis. To date, its protective effects against PM_2.5-induced intestinal injury in broilers remain largely unclear. This study investigated whether dietary RA supplementation mitigates intestinal damage and microbiota dysbiosis caused by PM_2.5 in broilers and explored the related mechanisms. (2) A total of 144 21-day-old broilers were randomly allocated to three groups, control (CON), PM_2.5 exposure (PM), and PM_2.5 exposure plus rosmarinic acid (RA), with six replicates of eight broilers each. (3) Results indicated that PM_2.5 exposure severely impaired growth performance, whereas dietary RA significantly increased average daily feed intake and average daily gain, decreased the feed-to-gain ratio, and elevated final body weight in broilers. RA significantly attenuated PM_2.5-induced intestinal inflammation, as evidenced by reduced expression of inflammatory cytokines (IL-6 and IFN-γ) and downregulation of key components in the TLR4 signaling pathway (TLR4, MyD88, and NF-κB). Inhaled PM_2.5 exposure impaired the intestinal epithelial barrier, marked by decreased mRNA levels of MUC2 and CLDN1 and increased caspase3 expression. Dietary RA treatment effectively restored these indicators, suggesting its role in maintaining epithelial integrity. Furthermore, RA reshaped the gut microbiota structure, altering both α- and β-diversity. Notably, RA led to a higher proportion of potentially health-promoting bacterial taxa, including Lactobacillus, V9D2013_group, and Oscillospirales, while reducing opportunistic pathogens like Shuttleworthia. (4) In conclusion, RA alleviates PM_2.5-induced intestinal inflammation, reinforces the epithelial barrier, and modulates the intestinal microbiota in broilers, likely through inhibition of the TLR4/NF-κB signaling. These findings reveal a novel mechanism by which RA mitigates pollutant-induced intestinal injury via gut microbiota modulation and TLR4/NF-κB suppression, offering new insights into the gut–lung axis in avian species. Full article

The H5N1 subtype of highly pathogenic avian influenza (HPAI) poses a major zoonotic threat due to its high fatality rate and capacity for cross species transmission. In early 2025, Argentina detected a novel triple reassortant A(H5N1) virus in Chaco Province, combining Eurasian, North American, and South American lineage segments. Genomic analyses of subsequent outbreaks in Buenos Aires and Entre Ríos confirmed persistence of this reassortant and additional HA substitutions (T204K, P251S) potentially linked to increased mammalian receptor affinity. Although PB2 sequences lacked canonical mammalian-adaptive markers (E627K, Q591K, D701N), all contained I292M, a mutation associated with human adaptation. Phylogenetic analyses revealed distinct genotypes and increasing divergence. These findings indicate ongoing viral evolution and adaptation within Argentina, emphasizing the urgent need for sustained genomic surveillance, timely data sharing, and integrated One Health strategies to mitigate zoonotic and socioeconomic risks associated with H5N1 spread in South America. Full article