The facial swelling is primarily around the eye and not always involving the infra-orbital sinus. Mortality can be as high as 50 percent but usually no more than 20 percent. The course and mortality of the disease correlate with the virulence of the pathogen, treatment, and concomitant infections. In the acute stage, the principal lesions are swollen face, watery eyes, rhinitis, nasal exudates that become crusty on the beak around nostrils and cheesy in nostrils and sinuses. Eyelids stick together by the exudate or an accumulation of cheesy exudate in the conjunctival sac.
Early exudates are copious, grayish-yellowish, thick and sticky.
Other lesions include tracheitis, bronchitis and on occasion air sacculitis. A presumptive diagnosis can be rendered on the flock history, progress of the disease and the lesions. When present, the fetid odors of nasal exudates are diagnostic. Confirmation requires laboratory diagnostic work up with isolation and identification of the organism. The organism can be demonstrated in a gram-stained smear of the nasal exudates.