Transmission:
Chronically ill or healthy carrier birds are the reservoir of infection. Chickens of all ages are susceptible, but susceptibility increases with age. The incubation period is 1-3 days, and the disease duration is usually 2-3 wk. Under field conditions, the duration may be longer in the presence of concurrent diseases, eg, mycoplasmosis.
Infected flocks are a constant threat to uninfected flocks. Transmission is by direct contact, airborne droplets, and contamination of drinking water. . Egg transmission does not occur.In the mildest form of the disease, the only signs may be depression, a serous nasal discharge, and occasionally slight facial swelling. In the more severe form, there is severe swelling of one or both infraorbital sinuses with edema of the surrounding tissue, which may close one or both eyes. In adult birds, especially males, the edema may extend to the intermandibular space and wattles. The swelling usually abates in 10-14 days; however, if secondary infection occurs, swelling can persist for months. There may be varying degrees of rales depending on the extent of infection. In Argentina, a septicemic form of the disease has been reported, probably due to concurrent infections. Egg production may be delayed in young pullets and severely reduced in producing hens. Birds may have diarrhea, and feed and water consumption usually is decreased during acute stages of the disease. isolation methods are the best way to avoid the disease.
Because early treatment is important, water medication is recommended immediately until medicated feed is available. Erythromycin and oxytetracycline are usually beneficial. Several new-generation antibiotics (eg, fluoroquinolones, macrolides) are active against infectious coryza. Various sulfonamides, sulfonamide-trimethoprim, and other combinations have been successful but must not be used in layers. In more severe outbreaks, although treatment may result in improvement, the disease may recur when medication is discontinued.
Preventive medication may be combined with a vaccination program, if started pullets are to be reared or housed on infected premises
I pulled the info from the Merck Veternary Manual
