Histopathological study on the trachea, intestine, and bursa of Fabricius during coinfection: Gumboro with infectious bronchitis disease and colibacillosis of broiler chickens in Algeria

Chickens, which are vital for meat and egg production globally, are susceptible to various diseases, including viral infections, that can lead to significant economic losses in the poultry industry. Infectious bursal disease (IBD) and avian infectious bronchitis (AIB) are two common viral diseases that affect chickens and have the potential for severe outbreaks. IBD suppresses the immune system, increasing the vulnerability of chickens to other infections, whereas IB causes respiratory issues, decreased egg production, and nephritis. Coinfections involving both viruses and bacterial pathogens such as Escherichia coli can exacerbate symptoms and increase mortality rates. A study conducted in Algeria on a poultry farm with 5,000 chickens reported an increase in death rates starting at 20 days of age, which was caused by coinfection with IBD, IB, and colibacillosis confirmed by a commercial antigen ELISA kit and passed through a hematoxylin and eosin staining protocol. Histopathological examination revealed extensive damage to the respiratory, digestive, and immune systems, including inflamed tracheas, congested lungs, and atrophied intestines. Microscopically, the trachea exhibits desquamation, thickened mucosa, and lymphocytic infiltration. The number of alveolar and tracheal gland cells decreases, and severe tissue degeneration occurs. The intestine shows edema, congestion, and villus atrophy, resulting in digestive issues. The bursa of Fabricius shows depletion, degeneration, and necrosis of lymphocytes, with cystic spaces in bursal follicles, which aligns with findings from previous studies. The weakened immune response due to IBD increases the susceptibility of broilers to secondary infections such as IB and colibacillosis, complicating their diagnosis and treatment.