It's normal for birds to sneeze on occasion, normally caused by environmental factors or by the bird itself, such as inhalation of feed dust or dust bathing.
Respiratory disease symptoms show more than just sneezing.
Here's a list of the most common poultry diseases that chickens get:
Mycoplasma Gallisepticum (MG), Mycoplasma Synoviae (MS), Infectious Coryza, Infectious Bronchitis (IB), and Infectious Laryngotracheitis (ILT).
https://edis.ifas.ufl.edu/ps044
Respiratory disease symptoms show more than just sneezing.
Here's a list of the most common poultry diseases that chickens get:
Mycoplasma Gallisepticum (MG), Mycoplasma Synoviae (MS), Infectious Coryza, Infectious Bronchitis (IB), and Infectious Laryngotracheitis (ILT).
https://edis.ifas.ufl.edu/ps044