Which agents frequently co-infect birds alongside *A. paragallinarum* causing a more severe syndrome?
*Mycoplasma gallisepticum* (MG) and Infectious Bronchitis Virus (IBV)
The clinical presentation of Coryza is frequently complicated and intensified by the presence of other infectious agents that occur concurrently with the primary bacterial cause. Pathogens such as *Mycoplasma gallisepticum* (MG) and Infectious Bronchitis Virus (IBV) are commonly isolated alongside *A. paragallinarum*. The synergy between these co-infectors and the main agent often leads to more severe manifestations of respiratory distress, potentially including marked edema. For instance, the presence of *M. gallisepticum* or IBV can significantly diminish the bird’s overall resistance, allowing the *A. paragallinarum* infection to become dominant, or conversely, allowing opportunistic organisms like *E. coli* to cause severe secondary bacterial pneumonia.
