Introduction: Infectious laryngotracheitis (ILT) is a highly contagious upper respiratory tract disease of chickens caused by a Gallid herpesvirus 1 (GaHV-1). The current study was to establish molecular evidence of Infectious laryngotracheitis virus (ILTV) in the Amhara region, Ethiopia, and determine its seroprevalence in areas of high chicken population and assess the risk factors associated with the disease.Methods: Serological study was conducted on 385 serum samples collected from commercial and backyard chickens in the study area, and the presence of antibodies against ILTV was determined by indirect ELISA. In addition, oropharyngeal swab samples were collected from chickens suspected of ILT infection and inoculated into embryonated chicken eggs through the Chorioallantoic membrane (CAM) route for isolation of the virus. Isolates were confirmed using polymerase chain reaction (PCR) upon amplification of ICP4 gene. Furthermore, potential factors were recorded, and their association with the virus seropositivity assessed.Results: The overall seroprevalence of ILT in the study area was 19.4%. A significant difference (P < 0.05) among districts, and between commercial (14.2%) and backyard (22.9%) production systems was observed (P < 0.05). Significantly higher seroprevalence was observed in layers compared to broilers and dual-purpose chickens however, there were no significant differences in prevalence based on age and sex. Of all (n = 27) tested oropharyngeal swab samples, four were positive for ILTV by PCR targeting a 688 bp region of ICP4 gene. Three of the PCR positive cases were from backyard chickens, while one was from commercial chicken farms. Based on oropharyngeal samples tested using PCR, a quarter of the samples were positive for ILT.Discussion: The result confirms the presence of ILT infection in the Amhara region of Ethiopia using serological and molecular methods. The study shows chickens shed the virus potentially spreading the infection to other birds. Vaccination strategy, strict biosecurity measures, rapid diagnosis, and detection of latent carriers are recommended to control and eradicate the disease. Further studies on clinical cases and the molecular characterization of the target gene are needed to identify circulating strains.

Aflatoxins (AFLAs) are highly prevalent mycotoxins in poultry production and are known to impair immune function and may reduce vaccine responsiveness. Therefore, this study evaluated whether dietary supplementation with yeast cell wall (YCW) could modulate the immune response under AFLA challenge and support vaccine response in broilers. A total of 144 one-day-old chicks were distributed into four treatments: negative control (NC), AFLA-contaminated diet (2.5 ppm), YCW (500 g/t), and YCW + AFLA. Birds were vaccinated against Newcastle Disease Virus (NDV) on D14. Body weight, hepatic pathology, intestinal permeability, circulating immune cell populations, phagocytic activity, and NDV-specific antibody titers were evaluated throughout the experimental period. AFLA exposure induced significant hepatic lesions and reduced body weight on D35 but did not alter the systemic immune parameters or intestinal permeability. Liver lesions were not prevented by the use of YCW, but body weight was positively correlated to the YCW intervention. Interestingly, YCW supplementation modulated immune responses in a context-dependent manner. In birds not exposed to AFLA, YCW increased anti-NDV antibody titers following vaccination. Contrarily, under AFLA challenge (and only in this situation), YCW supplementation was associated with changes in circulating immune cell populations and increased monocyte phagocytic activity, but in the presence of AFLA, YCW did not associate with increased anti-NDV titers. These findings indicate that YCW uniquely modulates selected innate and adaptive immune responses in broiler chickens exposed to AFLA, which is an important biological interaction with relevance to feed formulation for animal production.

Fowl cholera is a highly infectious bacterial disease in poultry production. It is caused by Pasteurella multocida ( P. multocida ) and leads to significant health risks and financial losses. Therefore, this study is aimed at isolating, molecularly detecting, and analyzing the antibiogram of P. multocida from breeder chickens in Gondar City. A cross‐sectional study design with purposive sampling was employed to collect a total of 130 tracheal swab samples from breeder chickens showing clinical signs of fowl cholera between January 2023 and December 2023, based on case availability. Bacterial isolation was performed using bacteriological and biochemical tests. The isolated P. multocida was confirmed through conventional polymerase chain reaction (PCR) using a capsular serotype‐specific primer ( capA ). The antibiogram assessment of P. multocida against 10 antimicrobial agents was conducted using the Kirby–Bauer disk diffusion method. Descriptive statistics were used to analyze the isolation rate of the bacterium. Of the 130 sampled swabs, 10 (7.69%) tested positive for P. multocida in the phenotypic assay, and 3 (30%) of those isolates were positive for the hyaD/hyaC virulence gene. The study found that all three isolates were 100% sensitive to penicillin, ampicillin, norfloxacin, and florfenicol, while showing 100% intermediate sensitivity to streptomycin and 66.7% intermediate sensitivity to gentamycin, amoxicillin, tetracycline, trimethoprim/sulphamethoxazole, and kanamycin. The study confirms that P. multocida , the causative agent of fowl cholera in breeder chickens, is circulating in the area and exhibits varying antimicrobial sensitivity profiles.