Domestic Waterfowl Research Articles

From emergence to endemicity of highly pathogenic H5 avian influenza viruses in Taiwan

A/goose/Guangdong/1/96-like (GsGd) highly pathogenic avian influenza (HPAI) H5 viruses cause severe outbreaks in poultry when introduced. Since emergence in 1996, control measures in most countries have suppressed local GsGd transmission following introductions, making persistent transmission in domestic birds rare. However, geographical expansion of clade 2.3.4.4 sublineages has raised concern about establishment of endemic circulation, while mechanistic drivers leading to endemicity remain unknown. We reconstructed the evolutionary history of GsGd sublineage, clade 2.3.4.4c, in Taiwan using a time-heterogeneous rate phylogeographic model. During Taiwan’s initial epidemic wave (January 2015 - August 2016), we inferred that localised outbreaks had multiple origins from rapid spread between counties/cities nationwide. Subsequently, outbreaks predominantly originated from a single county, Yunlin, where persistent transmission harbours the trunk viruses of the sublineage. Endemic hotspots determined by phylogeographic reconstruction largely predicted the locations of re-emerging outbreaks in Yunlin. The transition to endemicity involved a shift to chicken-dominant circulation, following the initial bidirectional spread between chicken and domestic waterfowl. Our results suggest that following their emergence in Taiwan, source-sink dynamics from a single county have maintained GsGd endemicity up until 2023, pointing to where control efforts should be targeted to eliminate the disease.

Birds as reservoirs: unraveling the global spread of Gamma- and Deltacoronaviruses.

Avian migration is a global phenomenon that transcends geographical boundaries. These migratory birds serve as unwitting carriers of diverse Gammacoronaviruses (γ-CoVs) and Deltacoronaviruses (δ-CoVs). While recombination events have been documented among γ-CoVs in avian species and β-CoVs in mammals, evidence for recombination between CoVs of distinct genera remains limited. This minireview examines the prevalence of CoVs in both domestic waterfowl (ducks and geese) and wild bird populations inhabiting various regions. We investigate the dissemination patterns of γ-CoVs and δ-CoVs among these populations, highlighting their shared characteristics. Furthermore, the review explores the intricate web of cross-species transmission of δ-CoVs from wild birds to mammals, with a particular focus on pigs. Understanding the distinct features of CoVs harbored by waterfowl and wild birds and their potential for cross-species transmission is crucial for preparedness and response to future CoV epidemics.

Molecular Characterization of Newcastle Disease Virus Genotype VII.1.1 from Egyptian Mallard Ducks with Nervous Manifestations

In Egypt, Newcastle disease virus (NDV) strains of genotype VII are known to be mild in domestic waterfowl and considered reservoirs. This is the first report for the detection of NDV GVII.1.1 from ducks showing severe clinical signs with high mortalities and nervous manifestations, additionally, isolation of NDV and molecular characterization for full HN and F genes were performed. In the current study, 16 backyard mallard duck flocks showing severe nervous signs with high mortalities were investigated by real-time RT-PCR using primers specific for the Fusion gene of NDV and matrix gene for avian influenza virus (AIV). Fourteen duck flocks tested positive for AIV and only two flocks tested positive for NDV infection. NDV was isolated from the trachea and brain of the same duck from each flock then full HN and F genes were sequenced. The phylogenetic analysis of the F and HN genes indicated that these strains were clustered with NDV genotype VII 1.1. The F gene had a specific mutation that cluster them in a new branch with with A11T in the signal peptide, N30S, T324A, and 480K in the hydrophobic heptad repeat (HRc) compared to the Lasota strain. The duck strains of NDV isolated from the brain had N294K in the hydrophobic heptad repeat-b (HRb) of F protein compared to the strains isolated from the trachea of the same duck, which may have a role in crossing the blood-brain barrier. The HN protein had a specific mutation that clustered them in a new branch with mutations of A4V, R15K in the cytoplasmic region, A28T in the transmembrane domain, and S76L in the HRa. In addition, HN protein had A50T, S54R T232N, P392S, and T443V, and multiple mutations were detected in the neutralizing epitopes specific to strains in the present study (N120G, K284R, S521T) that can alter virus antigenicity. The current study indicated the continuous evolution of NDV strains from genotype VII circulating in Egypt with increasing pathogenicity in ducks. The present findings demonstrated the urgent need for the vaccination of ducks and geese with killed NDV vaccines to reduce economic losses due to virus infection and prevent transmission to chickens helping in ND control in Egypt.

AVIAN INFLUENZA A VIRUS SURVEILLANCE IN RESERVOIR DOMESTIC DUCKS (Anas platyrhynchos domesticus) IN MAIDUGURI METROPOLITAN COMMUNITY OF NORTH-EASTERN NIGERIA: A NEED FOR ONE-HEALTH APPROACH

The domestic ducks (Anas platyrhynchos domesticus) are natural reservoir hosts of avian influenza A virus (AIV) and have since remained significant in the ecology and epidemiology of the virus globally. Continued local surveillance for AIV in this specie is critical to assessing the risks of potential spreading to domestic poultry, other animal species, and zoonotic transmission to humans. In this study, we investigate the status of AIV in domestic waterfowls in Maiduguri metropolis. Twenty-eight cloacal and oropharyngeal swab samples were collected from apparently healthy domestic ducks from November to December 2021 in Bulumkutu (n=2), Giwa Barracks (n=5), Kasuwan Shanu (n=4), Maimalari Barracks (n=5), Mairi (n=5), Premier (n=2) and Shehuri (n=4). Samples were screened for AIV using the real-time RT-PCR molecular assay. A total prevalence of 60.7% (CI: 41.99 –77.32) was recorded. Prevalence based on locations was higher in Bulumkutu 100% (CI:22.36 - 100), Kasuwan Shanu 100% (CI: 22.36 - 100), and Shehuri 100% (CI:47.29 - 100). In Maimalari Barracks and Mairi, prevalence of 60% (18.24 – 92.65) each was recorded respectively. While samples from Giwa Barracks and Gomari had a prevalence of 40% (CI: 7.346 – 81.76) and 33.3% (1.667 – 86.8). AIV was not detected in samples from premier (0%). The result of this study revealed the status of AIV in domestic ducks in Maiduguri metropolis. Thus, this early warning call the need for AIV prevention and control in the region and using the one-health approach to access the zoonotic potential of the virus in the domestic ducks...

Gross and histological studies of the female reproductive tract of the spur-winged goose (<i>Plectropterus gambensis</i>)

The extinction of most wild avian species is becoming apprehensive and some water fowls like the spur-winged goose (Plectropterus gambensis) may represent a good model for research, to advance wildlife conservation of related avian species. Currently, there are no baseline information regarding the anatomic characteristics of the reproductive tract of this species, hence; the present study aimed at investigating the gross and histological features of the ovary and oviduct of the wild spur-winged goose. A total of five female adults spur-winged geese with ages between eight to ten months old were used for this study. The bird were purchased from a farm and transported to the Laboratory for quick decapitation and tissue processing. The birds were allowed to acclimatized for seven days, before humanely sacrificed by quick cervical dislocation and reproductive organs (ovary and oviduct) were harvested for both gross and histological evaluations. Thereafter, the ovary and oviduct were fixed, and stained with H & E for light microscopic evaluation using DB2 -180M Digital Biological Microscope at different magnifications (×40, ×100, and ×400). The gross finding on the ovary revealed that it is ovoid in shape and appeared as a cluster of sacs showing yellowish to whitish follicles of different sizes and have a poorly defined oviductal segment. The oviduct appeared to be the longest part of the female reproductive tract (12.5-14.5cm). Histologically, the ovary is characterized by a membrana granulosa surrounding the oocytes at various stages of development. Also, the oviduct is by simple cuboidal to columnar ciliated secretory epithelium, and connects the ovary to the cloaca as a thin and un-convoluted tube. In conclusion, this study provided valuable information to serve as a baseline model to further research and understand the reproductive anatomy of other related domestic and wild waterfowl species.

Evolution and biological characteristics of the circulated H8N4 avian influenza viruses1

The circulating avian influenza viruses in wild birds have a high possibility of spillover into domestic birds or mammals at the wild bird-domestic bird or bird-mammal interface. H8N4 viruses primarily circulate in migratory wild waterfowl and have rarely been identified in domestic birds. In this study, we summarized the spatial and temporal distribution of global H8 viruses, specified their natural reservoirs, and performed detailed evolutionary analysis on the dominant H8N4 viruses. Here, we also reported a novel H8N4 virus isolated from a Eurasian coot sample from a wetland in eastern China in 2022. Animal infection studies indicated that the wild bird-originated H8N4 virus can replicate and transmit efficiently in ducks but has not adapted to chickens. Additionally, this naturally isolated H8N4 virus can replicate in mice without prior adaptation. These results indicate that H8 viruses exist mainly in the wild duck reservoir and pose a high infection risk to domestic ducks. Therefore, the active surveillance of influenza viruses at the wild and domestic waterfowl interface will contribute to monitoring the circulation of these viruses.

Economic aspects of goose and duck breeding development

The issues of goose and duck farming have not been raised at the economic level for a long time. Over the last decade, National Statistics Bureau Agency for Strategic Planning and Reforms of the Republic of Kazakhstan has not had information on the development of this type of poultry farming. Due to it the authors raised questions about the need for and prospects of the industry. The purpose of the article is to show the possible prospects for expanding the production of goose and duck breeding in our country as well as to identify the barriers that hinder their development. The results of the study can be applied in agricultural formations, peasant or farm enterprises. The abstract– logical method allows you to reveal the opportunities for Kazakhstan to develop poultry in the form of geese and ducks; the statistical method helped the authors to consider options for the development of the market for ducks and geese by using examples from other countries. In the world practice the meat of geese and ducks, which contains biologically valuable proteins and lipids. It has a higher energy value, as well as a high quality of production under relatively light conditions for care and cultivation. The authors give a comparative characteristic of the energy value of various types of meat, show options for using additional products of domestic waterfowl. Statistics on the prices of goose and duck meat, characteristics of their consumer properties, and recommendations for improving the development of the industry are given. The issues of food security of the population can be solved by expanding the market under consideration and through cooperation with stable agricultural and processing enterprises. Business development requires a small amount of government support in the form of concessional lending, temporary reduction or elimination of taxes.

Circulation of Antibiotic-Resistant Escherichia coli in Wild and Domestic Waterfowl in Ukraine.

Background: Antibiotic resistance is becoming an increasingly urgent problem for human and animal health due to the widespread use of antibiotics in medicine, veterinary medicine, and agriculture. At the same time, the natural reservoirs of antibiotic-resistant pathogens remain unclear. Wild birds may play a role in this due to their biology. Escherichia coli is a representative indicator pathogen for antibiotic resistance studies. Materials and Methods: In 2020-2021, sampling of feces and cloacal swabs from six species of wild waterfowl (Eurasian wigeon Anas penelope, Eurasian teal Anas crecca, white-fronted goose Anser albifrons, red-breasted goose Rufibrenta ruficollis, graylag goose Anser anser, shelduck Tadorna tadorna) and from two species of domestic waterfowl (ducks and geese) was conducted in the Kherson, Zaporizhzhia, Odesa, Kharkiv, and Cherkasy regions of Ukraine. Biological material was collected, stored, and transported in cryotubes with transport medium (brain heart infusion broth [BHIB] with the addition of 15% glycerol) in liquid nitrogen. Bacteriological studies were carried out according to standard methods for the isolation and identification of microorganisms. Drug resistance of E. coli was carried out by a standard disk diffusion method. Results: Bacteria representing six families (Enterobacteriaceae, Yersiniaceae, Morganellaceae, Bacillaceae, Pseudomonadaceae, Staphylococcaceae) were isolated from clinically healthy wild birds (wigeon, Eurasian teal, white-fronted goose, red-breasted goose, mallard, graylag goose, shelduck) in the southern regions of Ukraine with isolation rates ranging from 26.7% to 100%. A total of 19 E. coli isolates were cultured from 111 samples from wild birds, and 30 isolates of E. coli were cultured from 32 poultry samples. E. coli was isolated from birds of all species. The prevalence of E. coli ranged from 5.0% to 33.3% in wild waterfowl and from 90.9% to 100% in domestic waterfowl. The prevalence of multidrug-resistant (MDR) E. coli ranged from 10.0% to 31.8% in wild and domestic waterfowl: 3 of 15 (20%) specimens from wild mallard were MDR in the Kherson region, as well as 7 of 22 domestic ducks (31.8%) and 1 of 10 geese (10%) in the Kharkiv and Cherkasy regions. Isolates from wild birds were the most resistant to ampicillin (AMP), amoxiclav (AMC), amoxicillin (AMX), doxycycline (DO), and chloramphenicol (C). Isolates from poultry were resistant to ampicillin, amoxiclav, doxycycline, amoxicillin, chloramphenicol, and enrofloxacin (EX). Most of the other E. coli isolates from wild waterfowl were classified as non-multidrug-resistant (non-MDR) forms. Analysis of antibiotic sensitivity phenotypes showed that only four antibiotic-resistant phenotypes were detected among non-MDR bacteria, whereas among the MDR bacteria, two antibiotic-resistant phenotypes were detected in mallards and six in domestic waterfowl. Conclusion: The results of this study showed that wild waterfowl in Ukraine, which live in natural conditions and do not receive any antimicrobial drugs, are carriers of E. coli that are resistant to a number of antibiotics that are actively used in industrial poultry.

Epidemiology, genetic diversity, and evolutionary dynamics of Tembusu virus.

Tembusu virus (TMUV) is an emerging pathogenic flavivirus associated with acute egg-drop and fatal encephalitis in domestic waterfowl. Since its initial identification in mosquitoes in 1955, TMUV has been confirmed to infect ducks, pigeons, sparrows, geese, and chickens, posing a significant threat to the poultry industry. Here, we sequenced two DTMUV strains isolated in 2019 and systematically investigated the possible origin, genetic relationships, evolutionary dynamics, and transmission patterns of TMUV based on complete virus genome sequences in the public database. We found that TMUV can be divided into four major clusters: TMUV, cluster 1, cluster 2, and cluster 3. Interestingly, we found that cluster 2.2 (within cluster 2) is the most commonly involved in interspecies transmission events, and subcluster 2.1.2 (within cluster 2.1) is currently the most prevalent cluster circulating in Asia. Notably, we also identified three positively selected sites in the E and NS1 proteins, which may be involved in virus replication, immune evasion, and host adaptation. Finally, phylogeographic analysis revealed that cluster dispersal originated in Southeast Asia and that short-distance transmission events have occurred frequently. Altogether, these data provide novel insights into the evolution and dispersal of TMUV, facilitating the development of rapid diagnostics, vaccines, and therapeutics against TMUV infection.

Ultrastructural characteristics of the reproductive organs of adult male helminth Heterakis dispar (Nematoda: Heterakidae)

Nematodes belonging to the Heterakidae family are similar in appearance and their identification causes certain difficulties. For this reason, there is a need to define new taxonomic characteristics. On the other hand, despite the fact that the nematode Heterakis dispar Schrank, 1790, included in the same family, has a wide distribution area, there is little information about the ultrastructure of the parasite. Research on the ultrastructure of the reproductive system of this helminth hase not been conducted. Parasitic worms collected from the caeca of birds were identified, following which, based on the accepted methods of electron microscopy, blocks were prepared, cut, stained, pictures and electrograms were prepared and described. In the present study, the ultrastructural characteristics of the reproductive organs (testis, seminal vesicle, vas deferens and ejaculatory duct) of the adult nematode H. dispar, a specific parasite of domestic waterfowl, were studied with the help of light and electron microscopic methods. The obtained results were compared with the structure of other studied species (H. gallinarum Gmelin, 1790 and H. spumosa Schneider, 1866) of the Heterakidae family. Firstly, it was revealed that the reproductive organs of the male nematode H. dispar are located in the pseudocoelomic cavity, which is considered a taxonomic sign of this family. As in other species of the family, the testis, seminal vesicle, and wall of the vas deferens of the male nematode H. dispar consist of a basement membrane and an epithelial layer. In addition to the basement membrane, muscular and epithelial layers, the wall of the ejaculatory duct is also composed of glandular cells in the front part of the duct. It was revealed that, in the lumen of the tubular reproductive organs of the adult male nematode H. dispar, germ-cells turn into spermatogonia in the germinal zone and spermatocytes in the growth zone of the testis, spermatids in the seminal vesicle, incomplete formed spermatozoa in the vas deferens, and fully formed spermatozoa in the ejaculatory duct of the parasite. The spicules of the parasite nematode, which are the secondary sexual organs consist of a thick cuticle on the outside, and hypodermal origin cells and processes of nerve cells (dendrites and axons) on the inside. Two processes are found on the spicules, which is not observed in other nematodes of the same family.

New Insights on the Neglected Avian Nematode Hystrichis tricolor: Hystrichiosis-Induced Proventriculitis in Synanthropic Egyptian Geese (Alopochen aegyptiaca Linnaeus, 1766) in Germany.

Hystrichis tricolor is a neglected avian enoplid nematode (superfamiliy Dioctophymatoidea) and known to parasitize various species of the Anatidae (Anas spp. and Mergus spp.) from the northern hemisphere, inducing mainly proventriculitis in domestic and wild waterfowl. Here, we focus on the pathological findings of naturally H. tricholor-infected Egyptian geese (Alopochen aegyptiaca) and a neozoan shelduck (Tandorninae) of Germany. Nowadays, this species is considered the fastest-spreading alien waterfowl species within Western Europe. Additionally, molecular sequencing coupled with phylogenetic characterization of H. tricolor is reported. Post mortem analyses unveiled patent gastric H. tricolor infections in eight of twelve infected birds (8/12; 66.7%), inducing proventriculitis resulting in large visible nodular lesions. Histopathological findings point to chronic host pro-inflammatory immune reactions. These results demonstrate the potential role of Egyptian geese as natural reservoir hosts of H. tricholor and highlight their possible role in parasite transmission (i.e., spillback) into endemic waterfowl species. Due to avian health concerns, the occurrence of hystrichiosis should be monitored in native waterfowl in the future, introducing appropriate management practices in conservation strategies of endemic wild birds not only in Germany but elsewhere in Europe.

Self-Assembled Nanoparticles with E Protein Domains I and II of Duck Tembusu Virus Can Induce a More Comprehensive Immune Response Against the Duck Tembusu Virus Challenge.

Duck Tembusu virus (DTMUV) is a pathogenic flavivirus that causes a substantial drop in egg production and severe neurological disorders in domestic waterfowl. Self-assembled ferritin nanoparticles with E protein domains I and II (EDI-II) of DTMUV (EDI-II-RFNp) were prepared, and its morphology was observed. Two independent experiments were conducted. First, Cherry Valley ducks aged 14 days were vaccinated with EDI-II-RFNp, EDI-II, and phosphate buffered solution (PBS, pH 7.4), and special and virus neutralization (VN) antibodies, interleukin 4 (IL-4) and interferon gamma (IFN-γ) in serum, and lymphocyte proliferation were detected. Second, the vaccinated ducks with EDI-II-RFNp, EDI-II, and PBS were injected with virulent DTMUV, clinical signs at 7 days postinfection (dpi) were observed, and mRNA levels of DTMUV in the lungs, liver, and brain at 7 and 14 dpi were detected. The results showed near-spherical nanoparticles EDI-II-RFNp with a 16.46 ± 4.70 nm diameters. The levels of specific and VN antibodies, IL-4 and IFN-γ, and lymphocyte proliferation in the EDI-II-RFNp group were significantly higher than those in the EDI-II and PBS groups. In the DTMUV challenge test, clinical signs and mRNA levels in tissue were used to evaluate protection of EDI-II-RFNp. EDI-II-RFNp-vaccinated ducks showed milder clinical signs and lower levels of DTMUV RNA in the lungs, liver, and brain. These results indicate that EDI-II-RFNp effectively protects ducks against the DTMUV challenge and could be a vaccine candidate to provide an effective and safe method for preventing and controlling DTMUV infection.

Prevalence, evolution, replication and transmission of H3N8 avian influenza viruses isolated from migratory birds in eastern China from 2017 to 2021

ABSTRACT The continued evolution and emergence of novel influenza viruses in wild and domestic animals poses an increasing public health risk. Two human cases of H3N8 avian influenza virus infection in China in 2022 have caused public concern regarding the risk of transmission between birds and humans. However, the prevalence of H3N8 avian influenza viruses in their natural reservoirs and their biological characteristics are largely unknown. To elucidate the potential threat of H3N8 viruses, we analyzed five years of surveillance data obtained from an important wetland region in eastern China and evaluated the evolutionary and biological characteristics of 21 H3N8 viruses isolated from 15,899 migratory bird samples between 2017 and 2021. Genetic and phylogenetic analyses showed that the H3N8 viruses circulating in migratory birds and ducks have evolved into different branches and have undergone complicated reassortment with viruses in waterfowl. The 21 viruses belonged to 12 genotypes, and some strains induced body weight loss and pneumonia in mice. All the tested H3N8 viruses preferentially bind to avian-type receptors, although they have acquired the ability to bind human-type receptors. Infection studies in ducks, chickens and pigeons demonstrated that the currently circulating H3N8 viruses in migratory birds have a high possibility of infecting domestic waterfowl and a low possibility of infecting chickens and pigeons. Our findings imply that circulating H3N8 viruses in migratory birds continue to evolve and pose a high infection risk in domestic ducks. These results further emphasize the importance of avian influenza surveillance at the wild bird and poultry interface.

Detection and assessment of risk factors associated with Newcastle disease virus infection in birds in backyard poultry in Laichau province of Vietnam

ABSTRACT Newcastle disease (ND) is a highly pathogenic and contagious viral infectious disease of poultry that causes a very serious problem for poultry production and economic loss worldwide. ND has been an epizootic disease in Vietnam. Information about the risk factors that are associated with virus transmission in backyard chickens in Vietnam is limited. To provide more epidemiological information about ND in Vietnam, this study was performed to estimate NDV prevalence and identify the risk factors for ND virus (NDV) infection in birds at the backyard flock level. Choanal swabs were taken from 400 randomly selected birds from 100 apparently healthy flocks from May to July 2020. Based on RT–PCR analysis, 43 of 400 swab samples (10.75%; 95% CI 8–14.17) and 21 of 100 flocks (21%; 95% CI 14.17–29.98) were positive for the fusion (F) gene of NDV. The management practice risks were: backyard flocks contacting wild birds (OR = 3.89; P = 0.030), mixed flocks with different types and species of birds (OR = 5.46; P = 0.004), and infrequency of cleaning and disinfecting poultry houses (OR (odds ratio) = 4.43; P = 0.034). The second and third risks (above) showed a positive interaction on the risk of NDV infection in birds (OR = 39.38; P = 0.001), and the first risk showed a negative interaction. Further studies on NDV surveillance in domestic waterfowl, longitudinal studies, a well-optimized RT-qPCR assay, and genetic characterization are needed. The development of handbooks, flyers, or lessons for educating poultry keepers are also needed. RESEARCH HIGHLIGHT RT–PCR was used to detect the F gene of NDV in choanal swabs. Risk factors associated with NDV-positive samples were determined. The evidence for NDV circulation in backyard healthy birds was observed. Contact with wild birds, mixed flocks, and poor hygiene were major risk factors.

Multiple independent introductions of highly pathogenic avian influenza H5 viruses during the 2020-2021 epizootic in France.

During winter 2020-2021, France and other European countries were severely affected by highly pathogenic avian influenza H5 viruses of the Gs/GD/96 lineage, clade 2.3.4.4b. In total, 519 cases occurred, mainly in domestic waterfowl farms in Southwestern France. Analysis of viral genomic sequences indicated that 3 subtypes of HPAI H5 viruses were detected (H5N1, H5N3, H5N8), but most French viruses belonged to the H5N8 subtype genotype A, as Europe. Phylogenetic analyses of HPAI H5N8 viruses revealed that the French sequences were distributed in 9 genogroups, suggesting 9 independent introductions of H5N8 from wild birds, in addition to the 2 introductions of H5N1 and H5N3.

Experimental infection of aquatic bird bornavirus in Muscovy ducks

Aquatic bird bornavirus (ABBV-1), an avian bornavirus, has been reported in wild waterfowl from North America and Europe that presented with neurological signs and inflammation of the central and peripheral nervous systems. The potential of ABBV-1to infect and cause lesions in commercial waterfowl species is unknown. The aim of this study was to determine the ability of ABBV-1 to infect and cause disease in day-old Muscovy ducks (n = 174), selected as a representative domestic waterfowl. Ducklings became infected with ABBV-1 through both intracranial and intramuscular, but not oral, infection routes. Upon intramuscular infection, the virus spread centripetally to the central nervous system (brain and spinal cord), while intracranial infection led to virus spread to the spinal cord, kidneys, proventriculus, and gonads (centrifugal spread). Infected birds developed both encephalitis and myelitis by 4 weeks post infection (wpi), which progressively subsided by 8 and 12 wpi. Despite development of microscopic lesions, clinical signs were not observed. Only five birds had choanal and/or cloacal swabs positive for ABBV-1, suggesting a low potential of Muscovy ducks to shed the virus. This is the first study to document the pathogenesis of ABBV-1 in poultry species, and confirms the ability of ABBV-1 to infect commercial waterfowl.

Philophthalmus gralli in domestic waterfowl: An environmental study in an urban area from Brazil.

Philophthalmosis is a zoonotic ocular disease that affects mainly domestic and wild avian species in different parts of the world. However, aspects related to its epizoology in domestic animals are not completely known. In the present study, 47 Muscovy duck (Cairina moschata), 8 mallards (Anas platyrhynchos platyrhynchos) and 6 African geese (Anser cygnoides), free-living in an urban lake in Belo Horizonte, Minas Gerais, Brazil, were evaluated for eye fluke infection. The animals were manually contained, and the conjunctival sac and nictitating membrane were evaluated by direct ophthalmic examination (DOE), in which the fluke burden was estimated by a semiquantitative scale. Moreover, the conjunctival sac lavage (CSL) technique was applied for the search of parasite eggs. When possible, the detected trematodes were carefully removed for fixed for taxonomic identification. In order to characterize the parasite-host-environmental system, malacological collections were performed at the locality, and the collected intermediate host mollusks (Melanoides tuberculata) were evaluated for infection with larval philophthalmids. In addition, wild vertebrates found dead in the locality, including one common gallinule (Gallinula galeata) and two capybaras (Hydrochoerus hydrochaeris), were necropsied for the search of eye flukes. Samples from the developmental stages obtained from the hosts were subjected to morphological and molecular studies (amplification and sequencing of a partial region of the Nad-1 gene). In the DOE, the presence of eye flukes was verified in 67% (4/6), 31% (15/47) and 25% (2/8) in geese, Muscovy ducks and mallards, respectively. In most cases, the birds showed mild parasitism (1-5 trematodes), with no apparent eye damage, characterizing a subclinical infection. In only one goose, which had a high fluke burden (20 trematodes), it was possible to obtain eggs by CSL. Regarding the malacological survey, 73/4545 (1.6%) specimens of M. tuberculata evaluated were found infected with megalurous cercariae, compatible with representatives of the family Philophthalmidae. Additionally, 147 flukes were recovered from a specimen of G. galeata found dead at the lake. The morphological and molecular study of parasites obtained from different hosts evaluated in this study enabled the identification of Philophthalmus gralli, a species native from Asia and introduced in the Americas. Factors such as the wide distribution of the intermediate host and the participation of domestic and wild reservoirs in the parasite transmission chain may favor the occurrence of parasite spillover from wild to domestic birds. Furthermore, the occurrence of the life cycle of P. gralli in an urban waterbody serves as an alert to the possibility of human cases of this zoonotic eye parasite.

Эпидемиологическая и эпизоотологическая характеристика гельминтов грызунов (Mammalia: Rodentia) Ленкоранской природной области Азербайджана

9 species of rodents belonging to the families Muridae and Cricetidae have been caught in different habitats of Lankaran natural region (dry steppe semi-desert habitats, humid subtropical temperate climate habitats, humid subtropical medium climate habitats, warm broad-leaved forest habitats, mountain forest steppe habitats and mountain steppe habitats) and dissected according to the complete helminthological autopsy method developed by K. I. Skryabin. These rodents are: brown rat Rattus norvegicus, house mouse Mus musculus L., wood mouse Apodemus (sylvaemus) sylvaticus L., grey hamster Cricetulus migratorius, Persian jird Meriones persicus, Tristram’s jird M. blackleri, European water vole Arvicola terrestris L., common vole Microtus arvalis and social vole M. socialis. We found members of 47 helminth species in the dissected rodents, including 7 species of trematodes, 14 species of cestodes, 25 species of nematodes and 1 species of acanthocephalus. Of these, 26 species were biohelminths and 21 species were geohelminths. For these helminth species, we conducted epidemiological and epizootological potential assessment; 10 helminth species were found to be of epidemiological and epizootological significance, because they infect humans and domestic animals. Out of all the trematodes, Gastrodiscoides hominis has epidemiological significance for humans and epizootological significance for domestic pigs, while Echinostoma mijagawai has epizootological significance for domestic waterfowl (ducks and geese). Among the cestodes, adult Taenia hydatigena and Alveococcus multilocularis have epizootological significance for dogs and cats, while their larvae have epidemiological significance for humans and epizootological significance for even-toed ungulates; Hydatigera taeniaeformis has epidemiological significance for humans and epizootological significance for dogs and cats; Taenia pisiformis has epizootological significance for cats; Hymenolepis diminuta has epidemiological significance for humans. One of the nematodes, Hepaticola hepatica, has epidemiological significance for humans and epizootological significance for dogs and cats. Syphacia obvelata has epidemiological significance for humans; one type of acanthocephalus — Moniliformis moniliformis — has epidemiological significance for humans and epizootological significance for dogs and cats.

Tembusu virus infection in laying chickens: Evidence for a distinct genetic cluster with significant antigenic variation.

Tembusu virus (TMUV) associated disease is a growing cause of egg production decrease and encephalitis in domestic waterfowl, with expanding distribution. In previous studies, TMUV isolates were phylogenetically classified into two genetic lineages and different clusters with varied pathogenicity. However, little is known about the phenotypic and virulence characteristics of cluster 3 isolates within the duck TMUV lineage. In this study, the etiological agent causing egg drop in a laying chicken farm in southern China was investigated and a TMUV was isolated from pooled tissue samples. Genome sequencing and phylogenetic analysis grouped the isolate into TMUV cluster 3 with closest relation to the mosquito-origin TMUV YN12193. Cross-neutralization testing using convalescent sera revealed significant antigenic variation between the isolate and a representative strain of cluster 2.2. The experimental infection of SPF hens confirmed the ability of the isolate to replicate in multiple tissues and led to ovary damage. Additionally, high seroconversion rates (95.83%-100%) were detected in the three flocks following retrospective investigation. Our study demonstrates the occurrence of cluster 3 TMUV infection in laying chickens and that the virus exhibits significant antigenic variation compared with cluster 2 TMUV.

Genetic and biological characteristics of the globally circulating H5N8 avian influenza viruses and the protective efficacy offered by the poultry vaccine currently used in China

The H5N8 avian influenza viruses have been widely circulating in wild birds and are responsible for the loss of over 33 million domestic poultry in Europe, Russia, Middle East, and Asia since January 2020. To monitor the invasion and spread of the H5N8 virus in China, we performed active surveillance by analyzing 317 wild bird samples and swab samples collected from 41,172 poultry all over the country. We isolated 22 H5N8 viruses from wild birds and 14 H5N8 viruses from waterfowls. Genetic analysis indicated that the 36 viruses formed two different genotypes: one genotype viruses were widely detected from different wild birds and domestic waterfowls; the other genotype was isolated from a whopper swan. We further revealed the origin and spatiotemporal spread of these two distinct H5N8 virus genotypes in 2020 and 2021. Animal studies indicated that the H5N8 isolates are highly pathogenic to chickens, mildly pathogenic in ducks, but have distinct pathotypes in mice. Moreover, we found that vaccinated poultry in China could be completely protected against H5N8 virus challenge. Given that the H5N8 viruses are likely to continue to spread in wild birds, vaccination of poultry is highly recommended in high-risk countries to prevent H5N8 avian influenza.