Common viral and bacterial avian respiratory infections: an updated review

Chlamydia psittaci: A zoonotic pathogen causing avian chlamydiosis and psittacosis

Chlamydia psittaci is an obligate intracellular gram-negative bacterium with a unique biphasic developmental cycle. It is a zoonotic pathogen with a wide range of hosts and can cause avian chlamydiosis in birds and psittacosis in humans. The pathogen is transmitted mainly through horizontal transmission between birds. Cross-species transmission sometimes occurs and human-to-human transmission has recently been confirmed. This review provides an updated overview of C. psittaci from the perspective of both avian chlamydiosis and psittacosis. We include the aspects of genotype, host-pathogen interaction, transmission, epidemiology, detection and diagnosis, clinical manifestation, management, and prevention, aiming to provide a basic understanding of C. psittaci and offer fresh insights focused on zoonosis and cross-species transmission.

Detection and molecular characterization of chicken parvovirus and chicken megrivirus in layer breeders affected by intestinal dilatation syndrome

RESEARCH HIGHLIGHTS

IDS presented pathognomonic dilatation of the jejunum up to Meckel's diverticulum.IDS caused weight loss, decreased egg production, and increased culling and mortality.Chicken parvovirus (ChPV) was consistently detected through PCR assays.Chicken megrivirus (ChMV) was consistently detected through viral metagenomics.

Seroprevalence of avian metapneumovirus (aMPV) among pullet and layer hens in Northern Thailand

Avian metapneumovirus (aMPV) poses a significant global threat to the respiratory and reproductive systems of poultry, yet its prevalence and impact in specific regions, such as northern Thailand, remain understudied. This study is the first comprehensive assessment of aMPV seroprevalence among layer hens in the region. By the application of Enzyme-Linked Immunosorbent Assay (ELISA), our findings reveal a high overall seroprevalence of 60.78%, with significantly higher rates among post-laying hens (70.87%) compared to pre-laying hens (47.02%). Regional variations were noted, Uttaradit province showing the highest seroprevalence at 74%. Factors such as overcrowded conditions and poor farm hygiene were implied as contributors to increased seropositivity. Comparison with global studies highlights aMPV's endemicity and emphasizes the need for targeted surveillance and biosecurity measures. Migratory birds were inferred as potential vectors, contributing to the spread of aMPV across different regions. This study provides crucial epidemiological data essential for optimizing vaccination strategies and enhancing disease management practices to safeguard poultry health and sustainable production in northern Thailand.

The therapeutic efficacy of neem (Azadirecta indica) leaf extract against coinfection with Chlamydophila psittaci and low pathogenic avian influenza virus H9N2 in broiler chickens

Avian chlamydiosis is a serious avian infection that carries a significant zoonotic danger to the poultry industry. The respiratory co-infections caused by the low pathogenic avian influenza virus H9N2 (LPAIV H9N2) also cause significant financial losses in the poultry industry. The purpose of this study was to examine the pathogenicity of Chlamydophila psittaci, and LPAIV H9N2 individually and in combination in broiler chickens, as well as to determine whether or not aqueous neem (Azadirachta indica) leaf extract is effective against infections caused by these pathogens. Therefore, 120 broiler cobb chicks were equally divided into 4 groups (30 birds each) with triplicates with 10 birds. Broilers in group 1 (G1) were infected with only C. psittaci, broilers in group 2 (G2) were infected with only LPAIV H9N2, broilers in group 3 (G3) were infected with C. psittaci and LPAIV H9N2, and broilers in group 4 (G4) remained not challenged and non-treated with any therapeutic or preventive treatment (negative control). At 21 d postinfection (dpi), birds in G1, G2, and G3 were divided into 3 subgroups of 10 birds each: subgroup (A) remained infected and untreated (positive control), subgroup (B) infected and received oxytetracycline for 5 consecutive d, and subgroup (C) infected and received 8% aqueous neem leaf extract for 5 consecutive d. The multiplication of C. psittaci in birds in G1, in various tissues was evaluated using Giemsa staining and the data showed that multiplication was much higher in the lung, spleen, and liver from 6 h to 21 dpi, but low in the heart from 8 to 21 dpi. During simultaneous co-infection in G3, the birds developed significant clinical symptoms and postmortem lesions (PM). Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect viral shedding from oropharyngeal and cloacal swabs between 2 dpi and 8 dpi, with cycle threshold (CT) values ranging from 22 to 24. In contrast, bacterial shedding began 6 h after infection and continued until 21 dpi, with CT values ranging from 23 to 26. Administration of an aqueous neem leaf extract at an 8% concentration (Group C) resulted in a numerical rise in average body weight across all treatment groups in the third and fourth week, as well as a reduction in LPAIV H9N2 and C. psittaci replication in the respiratory and gut of treated birds compared to those treated with oxytetracycline (Group B). Overall, respiratory co-infections pose a considerable risk to the poultry business, which is a big threat. To control C. psittaci and LPAIV H9N2 in broiler chickens, oral supplementation of 8% aqueous neem leaf extract is recommended. This treatment improves the birds' performance, as evidenced by an increase in their average body weight. In addition, the application of 8% aqueous neem leaf extract lowers C. psittaci replication within tissues and diminishes LPAIV H9N2 shedding.

Revealing the mechanism: the influence of Baicalin on M1/M2 and Th1/Th2 imbalances in mycoplasma gallisepticum infection

Mycoplasma gallisepticum (MG) is a pathogen that induces chronic respiratory illnesses in chickens, leading to tracheal and lung injury, and eliciting immune reactions that support sustained colonization. Baicalin, a compound found in scutellaria baicalensis, exhibits anti-inflammatory, antioxidant, and antibacterial properties. This study aimed to investigate the potential of baicalin in alleviating lung and cell damage caused by MG by restoring imbalances in M1/M2 and Th1/Th2 differentiation and to explore its underlying mechanism. In this research, a model for M1/M2 polarization induced by MG was initially developed. Specifically, infection with MG at a multiplicity of infection (MOI) of 400 for 6 h represented the M1 model, while infection for 10 h represented the M2 model. The polarization markers were subsequently validated using qRT-PCR, ELISA, and Western blot analysis. Baicalin disrupts the activation of M1 cells induced by MG and has the potential to restore the balance between M1 and M2 cells, thereby mitigating the inflammatory damage resulting from MG. Subsequent studies on MG-infected chickens detected imbalances in M1/M2 and Th1/Th2 differentiation in alveolar lavage fluid, as well as imbalances in macrophages and Th cells in the lung. The M1/Th1 model was exposed to MG for 5 d, while the M2/Th2 model was infected with MG for 7 d. The utilization of both light and electron transmission microscopes revealed that the administration of baicalin resulted in a reduction in the number of M1 cells, a decrease in cytoplasmic vacuoles, restoration of mitochondrial swelling and chromatin agglutination, as well as alleviation of alveolar rupture and inflammatory cell infiltration. Furthermore, baicalin restored MG-induced M1/M2 and Th1/Th2 imbalances and inhibited the phosphorylation of p38 and p65 proteins, thereby hindering the activation of the TLR4-p38 MAPK/NF-κB pathway. This study provides insights into the potential long-term effects of baicalin in MG infection and offers a theoretical basis for practical applications.

Virus-like particles in poultry disease: an approach to effective and safe vaccination

The poultry industry, a cornerstone of global food security, faces dynamic challenges exacerbated by viral diseases. This review traces the trajectory of poultry vaccination, evolving from traditional methods to the forefront of innovation Virus-Like Particle (VLP) vaccines. Vaccination has been pivotal in disease control, but traditional vaccines exhibit some limitations. This review examines the emergence of VLPs as a game-changer in poultry vaccination. VLPs, mimicking viruses without replication, offer a safer, targeted alternative with enhanced immunogenicity. The narrative encompasses VLP design principles, production methods, immunogenicity, and efficacy against major poultry viruses. Challenges and prospects are explored, presenting VLP vaccines as a transformative technique in poultry disease control. Understanding their potential empowers industry stakeholders to navigate poultry health management with precision, promising improved welfare, reduced economic losses, and heightened food safety.

Molecular Detection of Respiratory Tract Viruses in Chickens at the Point of Need by Loop-Mediated Isothermal Amplification (LAMP)

Accurate and timely molecular diagnosis of respiratory diseases in chickens is essential for implementing effective control measures, preventing the spread of diseases within poultry flocks, minimizing economic loss, and guarding food security. Traditional molecular diagnostic methods like polymerase chain reaction (PCR) require expensive equipment and trained personnel, limiting their use to centralized labs with a significant delay between sample collection and results. Loop-mediated isothermal amplification (LAMP) of nucleic acids offers an attractive alternative for detecting respiratory viruses in broiler chickens with sensitivity comparable to that of PCR. LAMP's main advantages over PCR are its constant incubation temperature (∼65 °C), high amplification efficiency, and contaminant tolerance, which reduce equipment complexity, cost, and power consumption and enable instrument-free tests. This review highlights effective LAMP methods and variants that have been developed for detecting respiratory viruses in chickens at the point of need.

The Association between Broiler Litter Microbiota and the Supplementation of Bacillus Probiotics in a Leaky Gut Model

Probiotics provided from hatch have a major influence on microbiota development, and together with environmental and bedding microbiota, shape the microbial community of the litter. We investigated the influence of probiotic supplementation and a leaky gut challenge induced using dexamethasone (DEX) on the litter microbial community and litter parameters. The probiotic product was a mix of three Bacillus amyloliquefaciens strains. The litter microbiota were compared to the microbial communities from other gut sections. The litter samples had higher microbial diversity compared to the caecum, gizzard, jejunum, and jejunal mucosa. The high similarity between the litter phylum-level microbiota and gizzard microbiota detected in our study could be a consequence of ingested feed and litter passing through the gizzard. Moreover, the litter microbial community is fundamentally distinct from the intestinal microbiota, as evidenced by the number of genera present in the litter but absent from all the intestinal sections and vice versa. Furthermore, LEfSe analysis identified distinct microbial taxa across different groups, with specific genera associated with different treatments. In terms of litter quality, the birds in the DEX groups had a significantly higher moisture content, indicating successful leaky gut challenge, while probiotic supplementation did not significantly affect the moisture levels. These findings provide comprehensive insights into the distinct microbiota characteristics of litter.

Respiratory disease complex due to mixed viral infections in chicken in Jordan

The global distribution of avian respiratory viruses highlights the need for effective surveillance programs and international collaboration to monitor viral circulation and implement timely control measures. In the current study, we aim to provide a comprehensive overview of avian respiratory viral infections in the poultry flocks in Jordan, focusing on the major viruses involved, their epidemiology, clinical manifestations, and evolution based on viroinformatics that will be helpful to improve the diagnostic methods, and control strategies including vaccines in the region. In this research, various poultry broiler groups in Jordan experiencing respiratory symptoms were tested for respiratory viral pathogens from January 2021 to February 2022. The mortality rates observed in the examined groups varied between 6% and 40%. The identified strains were authenticated using the RT-qPCR assay. Furthermore, they underwent in-depth characterisation through the sequencing of the complete spike (S1) gene for infectious bronchitis virus (IBV) and the haemagglutinin (HA) gene for avian influenza virus (AIV) subtype H9N2. Co-infection of IBV and AIV H9N2 viruses was detected through molecular analysis. The IBV strains showed affiliation with the variant groups GI-16 (3 strains) and GI-23 (9 strains) and exhibited numerous mutations. Meanwhile, H9N2 avian influenza viruses displayed various changes in amino acids within the HA gene, suggesting the influence of antibody-driven selection pressure. The phylogenetic analysis revealed that the H9N2 viruses identified in this investigation shared close genetic ties with EG3 (3 strains) and the Middle East group (ME1; 8 strains). These strains have been recently found in Jordan and nearby countries in the Middle East. Moreover, their HA genes exhibited similarities to viruses belonging to the G1-like lineage. In conclusion, avian respiratory viral infections remain a significant concern for the poultry industry, requiring constant vigilance and proactive measures to minimise their impact. Continued surveillance, robust diagnostic methods, effective vaccines, and international cooperation are essential components of a comprehensive approach to combat avian respiratory viral infections (AI, IBV, ND and ILT 'viruses) and safeguard avian health and global poultry production.

Effect of enrofloxacin on clinical parameters and mucociliary system of broilers challenged with H9N2 avian influenza/infectious bronchitis viruses

BACKGROUND

Effect of antibacterials on mucociliary system and clinical outcome of chickens with mixed viral respiratory conditions is not properly addressed.

OBJECTIVE

We evaluated enrofloxacin effects on clinical parameters and mucociliary system of broilers challenged with H9N2/IB viruses.

METHODS

Broilers (105), at the age of 25 days, were randomly allocated into three groups: Group 1 (negative control), no treatment; Group 2 (positive control [PC]) challenged by intranasal and intraocular route. Group 3 (antibiotic [AB]-treated) challenged and also received enrofloxacin started after manifestation of clinical signs (day 2 post-challenge [pc]) and continued for 5 days.

RESULTS

Administration of AB was not associated with appreciable changes in body weight, feed conversion ratio (FCR) or the severity of clinical signs although it slightly reduced mortality rate as compared to PC group (p > 0.05). Virus shedding period and number of virus positive tracheal and caecal tonsil samples were also statistically similar between PC and AB groups. In necropsy, the most profound effect of AB was decreased pleuropneumonia severity score on day 12 pc. Histopathological lesion scores were statistically the same between PC and AB groups. However, the administration of AB increased the number of tracheal goblet cells, with no effect on ciliostasis.

CONCLUSIONS

We found a weak positive effect of enrofloxacin administration in H9N2/IB-infected chickens. Considering the risks of AB treatment in broiler chickens, the results of this small-scale study do not encourage the benefit of enrofloxacin use in these viral diseases.

The risk of wild birds contaminating source water with zoonotic Cryptosporidium and Giardia is probably overestimated

Cryptosporidium and Giardia are important waterborne protozoan parasites that are resistant to disinfectants commonly used for drinking water. Wild birds, especially wild migratory birds, are often implicated in the contamination of source and wastewater with zoonotic diseases, due to their abundance near water and in urban areas and their ability to spread enteric pathogens over long distances. This review summarises the diversity of Cryptosporidium and Giardia in birds, with a focus on zoonotic species, particularly in wild and migratory birds, which is critical for understanding zoonotic risks. The analysis revealed that both avian-adapted and zoonotic Cryptosporidium species have been identified in birds but that avian-adapted Cryptosporidium species dominate in wild migratory birds. Few studies have examined Giardia species and assemblages in birds, but the non-zoonotic Giardia psittaci and Giardia ardeae are the most commonly reported species. The identification of zoonotic Cryptosporidium and Giardia in birds, particularly C. parvum and G. duodenalis assemblages A and B in wild migratory birds, is likely due to mechanical carriage or spillback from birds co-grazing pastures contaminated with C. parvum from livestock. Therefore, the role of wild migratory birds in the transmission of zoonotic Cryptosporidium and Giardia to source water is likely overestimated. To address knowledge gaps, it is important to conduct more extensive studies on the prevalence of Cryptosporidium and Giardia in a broader range of migratory wild birds. There is also a need to investigate the extent to which zoonotic infections with C. hominis/C. parvum and G. duodenalis assemblages A and B are mechanical and/or transient, and to assess the load and viability of zoonotic oo/cysts shed in avian faeces. Understanding the contribution of birds to zoonoses is essential for effective disease surveillance, prevention, and control.

Prebiotic effects of Talinum triangulare and Mangifera indica on slow growing broiler chickens (SASSO)

1

The study aim was to evaluate the prebiotic effects of Talinum triangulare and Mangifera indica used on slow growing broiler chickens.

2

Three hundred and sixty (360) slow-growing chicks of four weeks of age and similar weight were selected and divided into four (04) treatments (Positive Control, Negative Control, 2 % T. triangulare and 2 % M. indica) of 6 replicates with, fifteen (15) chicks per replicate, which made ninety (90) chicks per treatment.

3

At 12 week age, blood sample and cecal content were taken from 6 chickens per treatment to determine heamatological profile and fermentation parameters (Short Chain Fatty Acid). The data obtained were submitted to one-way analysis of variance (ANOVA) using the software R version 3.6.2 (R Core Team, 2019).

4

Results showed that growth performance, haematological parameters, acetic, butyric, valeric and caproic acids were similar between broilers fed with the leave powders and the positive control treatment. However, broilers fed with Talinum triangulare and Mangifera indica powders showed a lower mortality rate, compared to the negative and positive control treatments. Moreover, broilers fed with the leave powders showed significantly higher (p < 0.05) formic acid concentration than the other treatments.

5

Talinum triangulare and Mangifera indica leaves could have prebiotic properties because they stimulated the production of short-chain fatty acids that keep animals healthy.

The influence of Spirulina extract on pathogenicity, immune response, and vaccine efficacy against H9N2 avian influenza virus in specific pathogen free chickens

Avian influenza (AI) viruses pose a risk to the worldwide poultry industry. Ultimately, improving the efficiency of the H9N2 vaccine is necessary to better control low-pathogenic avian influenza-H9N2 by using natural immunostimulant. Therefore, the goal of the present study was to examine varying doses of the cyanobacterium Spirulina extract on the effectiveness of H9N2 vaccine. Thus, a total of 150 specific pathogen-free (SPF) chickens were allocated into 6 groups, 25 birds each, as follow: G1, G2, and G6 were supplemented with 200, 400, and 400 mg Spirulina extract/kg feed, respectively, whilst the feed in G3, G4, and G5 were not supplemented with Spirulina extract. At 21-days-old, only the chickens in G1, G2, and G3 were vaccinated with the H9N2 AI vaccine. After 4 wk postvaccination, the chickens in G1, G2, G3, G4, and G6 were challenged with H9N2 AI Egyptian strain. The challenged virus was selected from a recent circulating Egyptian strain during 2022, and it was related to A/quail/Hong Kong/G1/97-like virus lineage and clustered with G1-B sub-lineage EGY-2 group. It had a high amino acids identity percentage of 92.6% with the A/chicken/Iran/av1221/1998 (Boehringer Ingelheim) vaccine. The results of real-time reverse-transcriptase polymerase-chain-reaction (rRT-PCR) revealed that no shedding of the virus was reported in G1, G2, G3, and G5. The supplementation of Spirulina extract in low (200 mg/kg of feed) and high (400 mg/kg of feed) concentration with the birds vaccinated with H9N2 AI vaccine (G1 and G2) induced prominent immuno-stimulatory effect in a dose dependent manner where it strongly enhanced the phagocytic activities of broilers' peripheral blood monocytes, and lysozyme at all days postvaccination (dpv) and days postchallenge (dpc) compared to other groups with significant differences at all day of experiment and 21st dpv, 28th dpv, 7th dpc, and 14th dpc, respectively. The supplementation with Spirulina extract in G1 and G2 induced the highest hemagglutination inhibition antibody titer in a dose-dependent manner at all-time intervals. The antibody titer postvaccination was significantly increased in G1 and G2 at 14th, and 21st dpv, in comparison with G3. Furthermore, G1 and G2 showed higher significant antibody titers at 7th and 14th dpc, compared to other groups. Furthermore, Spirulina extract (200 and 400 mg/kg feed) in G1 and G2 showed anti-inflammatory effect in a dose dependant manner by downregulating nitric oxide levels at all times postchallenge with a significant difference at 3 to 7 dpc compared to G3, G4, and G6, with improved histopathological alterations in the trachea, lung, kidney, spleen, and bursa of Fabricius.  G6 supplied with 400 mg/kg Spirulina extract feed only without vaccination had a similar effect as vaccinated groups on innate immunity. However, it delayed the production of antibodies and did not prevent viral shedding as in vaccinated groups. In conclusion, vaccination in conjunction with either dose of Spirulina extract (G1, and G2) prevents viral shedding, increases the immune response, and reduces inflammation and histopathological change caused by H9N2 AI infection in a dose dependent manner. We recommend the use of 400 mg Spirulina extract/kg feed as a natural immunostimulant in conjunction with the H9N2 vaccine to achieve the highest possible level of protection against H9N2 AI infection.

Surveillance of Avian Metapneumovirus in Non-Vaccinated Chickens and Co-Infection with Avian Pathogenic Escherichia coli

Brazil is the second largest producer of broiler chicken in the world, and the surveillance of avian pathogens is of great importance for the global economy and nutrition. Avian metapneumovirus (aMPV) infection results in high rates of animal carcass losses due to aerosacculitis and these impacts can be worsened through co-infection with pathogenic bacteria, particularly Escherichia coli (APEC). The present study evaluated the seroprevalence of the main aMPV subtypes in unvaccinated broiler chickens from poultry farms in Brazil, as well as the clinical effects of co-infection with APEC. Blood samples, respiratory swabs, femurs, liver, and spleen of post-mortem broiler chickens were collected from 100 poultry production batches, totaling 1000 samples. The selection of the production batch was based on the history of systemic and respiratory clinical signs. The results indicated that 20% of the lots showed serological evidence of the presence of aMPV, with two lots being positive for aMPV-B. A total of 45% of batches demonstrated co-infection between aMPV and APEC. The results point to the need for viral surveillance, targeted vaccination, and vaccination programs, which could reduce clinical problems and consequently reduce the use of antibiotics to treat bacterial co-infections.

Metagenomic characterization reveals virus coinfections associated with Newcastle disease virus among poultry in Kenya

Newcastle disease (ND) is an endemic viral disease affecting poultry and causing massive economic losses. This cross-sectional purposive study detected coinfections that are associated with the Newcastle disease virus among poultry from selected regions in Kenya. Cloacal (n = 599) and oral-pharyngeal (n = 435) swab samples were collected and pooled into 17 and 15 samples, respectively. A total of 17,034,948 and 7,751,974 paired-end reads with an average of 200 nucleotides were generated from the cloacal and oral-pharyngeal swab samples, respectively. Analysis of the de novo assembled contigs identified 177 and 18 cloacal and oral-pharyngeal contigs, respectively with hits to viral sequences, as determined by BLASTx and BLASTn analyses. Several known and unknown representatives of Coronaviridae, Picobirnaviridae, Reoviridae, Retroviridae, and unclassified Deltavirus were identified in the cloacal swab samples. However, no Newcastle disease virus (family Paramyxoviridae) was detected in the cloacal swabs, although they were detected in the oropharyngeal swabs of chickens sampled in Nairobi, Busia, and Trans Nzoia. Additionally, sequences representative of Paramyxoviridae, Coronaviridae, and Retroviridae were identified in the oral-pharyngeal swab samples. Infectious bronchitis virus and rotavirus were chickens' most prevalent coinfections associated with the Newcastle disease virus. The detection of these coinfections suggests that these viruses are significant threats to the control of Newcastle disease as the Newcastle disease virus vaccines are known to fail because of these coinfections. Therefore, this study provides important information that will help improve disease diagnosis and vaccine development for coinfections associated with the Newcastle disease virus.

Surveillance of Escherichia coli in different types of chicken and duck hatcheries: one health outlook

Escherichia coli is an important zoonotic bacterium that significantly impacts one health concept. E. coli is normally detected in the gut of warm-blooded animals, but some serotypes can cause diseases in humans and animals. Moreover, it can continue for a long time in different environments, replicate in water, and survive outside different hosts. In this study, 171 samples collected from 10 different types of poultry hatcheries (automatic, semiautomatic, and manual "traditional" types) were examined for the prevalence of E. coli. PCR was applied to verify the E. coli isolates via 16S rRNA gene-specific primers. From the gathered samples, 62 E. coli isolates were recovered (36.3%). The highest prevalence was met with the manual "traditional" hatcheries (57.1%) with no significance difference (P = 0.243) in the 3 types of hatcheries. The incidence of E. coli varied significantly in different tested avian types and breeds. The prevalence was 35.7% in duck hatcheries and 37% in chicken hatcheries, with significant differences between breeds of both species (P = 0.024 and 0.001, respectively). The identification of zoonotic E. coli serotypes in this study is concerning, highlighting the need for collaborative efforts across various sectors, including social, environmental, and governance, to promote the adoption of the one health principle in the chicken business. Periodical surveillance, biosecurity measures at the hatcheries and farm levels, and boosting the immunity of birds were recommended to limit the risk of E. coli spread from avian sources to humans.

Ameliorative avian gut environment and bird productivity through the application of safe antibiotics alternatives: a comprehensive review

The avian digestive tract is an important system for converting ingested food into the nutrients their bodies need for maintenance, growth, and reproduction (meat, table eggs, and fertile eggs). Therefore, preserving digestive system integrity is crucial to bird health and productivity. As an alternative to antibiotics, the world has recently turned to the use of natural products to enhance avian development, intestinal health, and production. Therefore, the primary goal of this review is to explain the various characteristics of the avian digestive tract and how to enhance its performance with natural, safe feed additives such as exogenous enzymes, organic acids, photogenic products, amino acids, prebiotics, probiotics, synbiotics, and herbal extracts. In conclusion, the composition of the gut microbiome can be influenced by a number of circumstances, and this has important consequences for the health and productivity of birds. To better understand the connection between pathogens, the variety of therapies available, and the microbiome of the gut, additional research needs to be carried out.