Avian diseases最新文献

Infectious coryza (IC) is a respiratory disease of chickens, including pullets, layers, and broilers, caused by the bacteria Avibacterium paragallinarum (AP), which was previously known as Hemophilus gallinarum. IC classically causes production decreases and mortality in chickens, frequently paired with swelling of the sinuses, mucoid nasal discharge, and respiratory rales. Although IC is considered an endemic disease of chickens in California, it has been unusual to rare in commercial chickens in Pennsylvania. The last reported IC case in Pennsylvania was in 2002, involving broiler breeders. However, between December 2018 and December 2019, 68 farms were affected by IC in Pennsylvania, involving approximately 14 million birds. Several farms had multiple flocks affected. Most affected farms housed layer chickens (37/68), but a smaller number of broiler farms, pullet farms, and layer breeder farms have been affected. Ages of affected birds and duration of disease were variable between flocks, as were the severity of clinical signs, pathologic lesions, and rates of mortality. PCR testing has greatly aided and sped diagnostic efforts in addition to traditional bacterial culture. In eight layer cases and five broiler cases, bacterial culture of the sinus or choanal cleft proved unrewarding, whereas culture of trachea, air sacs, lungs, heart, or liver were diagnostic. Although cases of IC in commercial Pennsylvania poultry continue, they have been greatly reduced because of implementation of a successful vaccination program. In this case series report we detail epidemiologic, clinical, and pathologic aspects of this outbreak and discuss vaccination as a control measure of IC in the state of Pennsylvania.

Fowl typhoid (FT) caused by Salmonella Gallinarum (SG) is a poultry disease distributed worldwide that has been eradicated in commercial production of many developed countries but still persists in many developing countries. Vaccination is one of the main strategies to reduce mortality, clinical signs, and vertical or horizontal transmission. The aim of this work was to assess the protection against FT conferred by vaccines based on Salmonella Enteritidis (SE), SG, or a combination. Five experimental groups of birds, vaccinated with different live or inactivated SG and SE vaccines were included in the trial: 1) two doses of a SG-SE bivalent inactivated vaccine; 2) four doses of the live attenuated SE vaccine; 3) three doses of the live attenuated SE vaccine and two doses of the SG-SE bivalent inactivated vaccine; 4) two doses of the live attenuated SG9R vaccine; and 5) unvaccinated birds. At 28 wk of age, all hens were challenged with a virulent strain of SG, and mortality was recorded during the subsequent 15 days. The results showed that the plan that included only the inactivated vaccine did not show significant protection (P = 1), while the plan based on the administration of the attenuated strain of SE significantly reduced mortality in the group of birds (P = 0.0309). However, the highest levels of protection were obtained in the group of hens immunized with the combination of the inactivated vaccine and the live attenuated SE strain (P < 0.0001), which was statistically similar to the homologous protection conferred by the SG 9R strain, a vaccine used in many countries to control FT. These results demonstrate that the combination of existing vaccines together with strict biosecurity measures on farms may help improve the control of the pathogen in countries where FT in an emerging or reemerging disease.

Plant essential oils (EOs) possess established antimicrobial properties; however, research on their antiviral activity, particularly against avian coronaviruses, remains limited. EOs offer a promising plant-based alternative for viral control, especially in scenarios where conventional chemical use is restricted. This study aimed to evaluate the antiviral effects of six different essential oils derived from Syzygium aromaticum, Origanum vulgare, Cymbopogon martinii, Cymbopogon citratus, Mentha piperita, and Mentha spicata against avian coronavirus (AvCov) at 0.1% and 1% dilutions. The antiviral effects of the EOs were assessed via virus isolation from embryonated chicken eggs, and the ability of the EOs to inhibit AvCoV replication was evaluated. The EOs from Syzygium aromaticum, Origanum vulgare, Cymbopogon martinii, and Cymbopogon citratus completely inhibited AvCov replication at a 1% dilution. Conversely, absent to partial inhibitory effect was observed at the 0.1% dilution for all tested EOs, with O. vulgare derived EO exhibiting the greatest inhibitory effect (over 70%). Notably, EOs from Mentha piperita and Mentha spicata were unable to completely inhibit AvCov at either concentration. Our findings highlight the potent antiviral activity of the EOs from Syzygium aromaticum, Origanum vulgare, Cymbopogon martinii, and Cymbopogon citratus against AvCov at a 1% dilution. The complete inhibition observed for these EOs suggests their potential for AvCov control. However, further research is necessary to elucidate the mechanisms of action, optimize formulations, and evaluate the efficacy against other coronaviruses, including those relevant to human health.

In 2022, a new epornitic of H5N1 highly pathogenic avian influenza (HPAI) virus clade 2.3.4.4b emerged in U.S. domestic poultry with high prevalence in wild bird populations. We describe pathological findings of HPAI H5N1 in nine wild birds encompassing eight different species, including Accipitriformes (red-tailed hawk, bald eagle), Cathartiforme (turkey vulture), Falconiforme (peregrine falcon), Strigiforme (one adult great-horned owl, one juvenile great-horned owl), Pelecaniforme (American white pelican), and Anseriformes (American green-winged teal, trumpeter swan). All these birds died naturally (found dead, or died in transit to or within a rehabilitation center), except for the bald eagle and American green-winged teal, which were euthanized. Gross lesions were subtle, characterized by meningeal congestion observed in the turkey vulture, bald eagle, and adult great-horned owl. Histologically, encephalitis was observed in all cases (9/9, 100%). Leukocytoclastic and fibrinoid vasculitis with necrotizing encephalitis was observed in the red-tailed hawk, great-horned owls, and American white pelican (5/9, 55.6%), and perivascular lymphohistiocytic encephalitis was seen in the turkey vulture, peregrine falcon, green-winged teal, and bald eagle (4/9, 44.4%). Coagulative necrosis or lymphohistiocytic/lymphoplasmacytic inflammation was identified in the kidney (6/8, 75%), liver (6/9, 66.7%), heart (5/9, 55.6%), and lung (2/9, 22.2%). Immunopositive signals against Influenza virus A nucleoprotein were predominantly detected within the brain (9/9, 100%), air sac (7/9, 77.8%), lung (7/9, 77.8%), kidney (6/8, 75%), heart (6/9, 66.7%), and liver (5/9, 55.6%). Additionally, other organs, such as the pancreas, spleen, intestines, gonads, and adrenals occasionally exhibited positive viral protein signals. In these organs, in addition to parenchymal cells, viral protein signals were often identified in endothelial cells. Our results suggest that the 2022-2023 HPAIV H5N1 clade 2.3.4.4b replicated systemically in all examined birds, with brain lesions being the most prevalent and associated with a subset of birds displaying clinical signs observed perimortem.

Gizzard erosion and ulceration syndrome (GEUS) is caused by a fowl adenovirus serotype 1 (FAdV-1) and was first reported in laying hens in Japan in 1993. This syndrome has emerged as an epizootic in Morocco since 2014, causing significant economic losses for the poultry industry, but no involvement of a FAdV has been confirmed. Thus, the objective of this work was to assess GEUS cases that occurred in the country and to determine the role of FAdVs in their occurrence. Investigations were based on a retrospective reassessment of tissue sections and paraffin blocks of gizzards and livers from GEUS cases between 2014 and 2021 coupled with a prospective search of cases in 2022. Gizzards and livers were fixed in 10% neutral buffered formalin for histopathologic examinations according to standard methods and stored at -20 C for molecular analysis. After deparaffinizing, 10-µm-thick tissue sections along with fresh organs were subjected to DNA extraction using a commercial kit. A primer pair specific for the Hexon gene of FAdVs was used in conventional PCR; in contrast, for real-time PCR, a primer pair targeting the 52K gene was employed. In total, 24 flock cases with characteristic GEUS were assessed between 2014 and 2022. They were nine broiler cases aged between 11 and 39 days, 11 layer cases with an age between 17 and 29 wk, two cases in meat-type breeders aged 10 and 27 wk, and two flock cases of turkey poults aged 22 and 23 days. In most cases, microscopic lesions were consistent with an ulcerative and lymphoplasmocytic ventriculitis, and pathognomonic viral intranuclear inclusion bodies within degenerate epithelial cells were identified in four broiler flock cases, four layer cases, and one case in breeders and hence were highly suggestive of a FAdV infection. Among these nine cases that were positive at the histopathologic examination, six cases were found to be FAdV-PCR positive; another four cases were negative to histology but FAdV-PCR positive. Furthermore, a sequencing analysis was conducted, providing the initial evidence of the implication of FAdV-1 from species A as the cause of GEUS in Moroccan poultry. Additionally, a phylogenetic analysis was executed to facilitate a comparison between the strains investigated in this study and those identified in diverse geographic regions and across various time periods.

Cytokines are co-administrated with vaccines or co-expressed in the vaccine virus genome to improve protective efficacy by stimulating immune responses. Using glycosylphosphatidylinositol (GPI) anchoring by attachment to the target cytokine, we constructed recombinant Marek's disease virus (MDV) vaccine strain 301B/1 (v301B/1-rtg-IL-15) that expresses chicken interleukin-15 (IL-15) as the membrane-bound form at the cell surface. We evaluated the vaccine efficacy of v301B/1-rtg-IL-15 given as a bivalent Marek's disease (MD) vaccine in combination with turkey herpesvirus (HVT) against a very virulent plus MDV strain 648A challenge. The efficacy was compared with that of conventional bivalent MD vaccine, as a mixture with HVT plus parental v301B/1 or v301B/1-IL-15, which expresses a natural form of IL-15. The membrane-bound IL-15 expression did not interfere with the virus growth of recombinant v301B/1-rtg-IL-15. However, the MD incidence in birds vaccinated with v301B/1-rtg-IL-15 was higher than that of birds given the conventional bivalent MD vaccine containing parental v301B/1 virus, although the v301B/1-rtg-IL-15 vaccinated group showed increased natural killer cell activation at day 5 postvaccination, the same day as challenge. Overall, the protection of v301B/1-rtg-IL-15 was not improved from that of v301B/1 against very virulent plus MDV challenge.

The continued circulation of infectious bursal disease virus (IBDV) in Egypt, despite the use of various vaccines, is a serious problem that requires continuous detection of IBDV. In the current study, real-time reverse transcriptase polymerase chain reaction testing of 100 diseased chicken flocks during 2017-2021 revealed the presence of very virulent IBDV (vvIBDV) in 67% of the flocks, non-vvIBDV in 11%, and a mixture of both vvIBDV and non-vvIBDV in 4%. Twenty-nine IBDV isolates were submitted for partial sequencing of the viral protein 2 hypervariable region (VP2-HVR), and 27 isolates were confirmed to be genogroup A3 (vvIBDV) with 96.3%-98.5% similarity to the global A3 (vvIBDV) and 88.9%-97% similarity to genogroup A1 vaccine strains. The remaining two isolates were non-vvIBDV and showed 91.1% and 100% identity with classical genogroup A1 strains, respectively. Furthermore, the sequence and phylogenetic analysis of VP1 (amino acids 33-254) of two selected isolates of A3, 5/2017 and 98/2021, clustered them as B2, vvIBDV-like, strains with high similarity (99.5%) to four Egyptian, 99% to Chinese and European, and 97.7% to Chinese and Polish vvIBDV isolates. Experimental infection of commercial broiler chickens with two vvIBDV-A3B2 isolates (5/2017 and 98/2021) showed no mortality despite typical tissue lesions, clear histopathological changes, and strong ELISA antibody response. Isolate 98/2021 was more pathogenic, as confirmed by histopathology, whereas isolate 5/2017 induced a stronger serological response. In conclusion, vvIBDV (A3B2) strains with two amino acid (aa) substitutions in VP1 as V141I and V234I as well as VP2 as Y220F and G254S are still circulating in Egypt.

The poultry-housing environment plays a significant role in the transmission and persistence of the egg-associated pathogen Salmonella Enteritidis in laying flocks. The commercial egg industry is in the midst of a transition toward cage-free housing, but the food safety ramifications of this shift are not yet certain. The present study assessed internal organ colonization by Salmonella Enteritidis in layer pullets reared in cage-free housing and infected at two different ages. Groups of 280 pullets were transferred from the rearing facility (at 9 wk of age in one trial and 15 wk in another) to a containment facility with four isolation rooms simulating commercial cage-free barns with perches and nest boxes (70 birds/room). Twenty-four pullets in each room were orally inoculated with Salmonella Enteritidis immediately after placement in the containment facility. At 1-2 wk postinoculation in each trial, samples of liver, spleen, and intestinal tract were collected from all birds in two rooms for bacteriologic culturing to detect Salmonella Enteritidis. At 21-22 wk of age, samples of spleen, ovary, and intestinal tract were similarly collected and tested from all birds in the remaining two rooms. Among samples collected at 1-2 wk postinoculation, Salmonella Enteritidis was isolated significantly more often from groups of pullets infected initially at 15 wk of age than from those infected at 9 wk (61% vs. 38% of livers, 59% vs. 31% of spleens, and 84% vs. 57% of intestines). Among samples collected at 21-22 wk of age, the frequency of recovery of Salmonella Enteritidis was again significantly greater in birds infected at 15 wk of age than in those infected at 9 wk (16% vs. 6% of spleens, 9% vs. 1% of ovaries, and 26% vs. 10% of intestines). These data suggest that Salmonella Enteritidis infections introduced into flocks during the later stages of pullet rearing have greater potential to persist into the early phase of egg production.

Manufacturers of Mycoplasma gallisepticum (MG) modified live vaccines usually recommend a single application at 8 wk of age. This makes 12-16-wk-old layer pullets suitable for challenge studies intended to evaluate these vaccines. Numerous challenge models in different poultry species and ages have been reported. However, there is not an established layer pullet challenge model for this age. The aim of this study is to develop a suitable challenge model in 12-wk-old layer pullets. MG R_low strain was used as the challenge strain, and its ability to induce clinical signs and lesions in 12-wk-old Hy-Line W-36 layer pullets was evaluated. Three different doses (low, 7.95 × 10⁴ color-changing units [CCU]/bird; medium, 7.95 × 10⁶ CCU/bird; and high, 7.95 × 10⁸ CCU/bird) via three different routes (eye drop, fine spray, and contact infection) were compared and evaluated using different parameters. At 14 days post-challenge, there were no mortalities in any of the groups throughout the study. Layer pullets directly challenged with the high dose via the fine spray route showed the clearest and most consistent results (clinical signs, positive quantitative real-time PCR [qPCR], seroconversion, air sac scoring, and histopathological changes of the tracheal mucosa). Medium and low challenge doses applied via fine spray or eye drop did not show consistent results. R_low strain was able to spread to the contact infection birds, as confirmed by the positive qPCR results; however, none of the contact-infected birds showed any clinical signs or gross or microscopic lesions. Our results suggest that a high dose (7.95 × 10⁸ CCU/bird) administered through a fine spray route is the model of choice in any future MG vaccine evaluation trials in 12-wk-old layer pullets.

Outbreaks of infectious bronchitis (IB) continue to occur from novel variants of IB virus (IBV) emerging from selection of vaccine subpopulations and/or naturally occurring recombination events. S1 sequencing of Arkansas (Ark) -type viruses obtained from clinical cases in Alabama broilers and backyard chickens shows both Ark Delmarva Poultry Industry (ArkDPI) vaccine subpopulations as well as Ark vaccine viruses showing recombination with other IB vaccine viruses. IB Ark-type isolates AL5, most similar to an ArkDPI vaccine subpopulation selected in chickens, AL4, showing a cluster of three nonsynonymous changes from ArkDPI subpopulations selected in chickens, and AL9, showing recombination with Massachusetts (Mass) -type IBV, were examined for pathogenicity and ability to break through immunity elicited by vaccination with a commercial ArkDPI vaccine. Analysis of predicted S1 protein structures indicated the changes were in regions previously shown to comprise neutralizing epitopes. Thus, they were expected to contribute to immune escape and possibly virulence. Based on clinical signs, viral load, and histopathology, all three isolates caused disease in naïve chickens, although AL9 and AL5 viral loads in trachea were statistically significantly higher (30- and 40-fold) than AL4. S1 gene sequencing confirmed the stability of the relevant changes in the inoculated viruses in the chickens, although virus in some individual chickens exhibited additional S1 changes. A single amino acid deletion in the S1 NTD was identified in some individual chickens. The location of this deletion in the predicted structure of S1 suggested the possibility that it was a compensatory change for the reduced ability of AL4 to replicate in the trachea of naïve chickens. Chickens vaccinated with a commercial ArkDPI vaccine at day of hatch and challenged at 21 days of age showed that vaccination provided incomplete protection against challenge with these viruses. Moreover, based on viral RNA copy numbers in trachea, differences were detected in the ability of the vaccine to protect against these IBV isolates, with the vaccine protecting the most poorly against AL4. These results provide additional evidence supporting that IBV attenuated vaccines, especially ArkDPI vaccines, contribute to perpetuating the problem of IB in commercial chickens.