Coryza in Chickens

Infectious coryza, caused by the Haemophilus paragallinarum bacteria, is the chicken equivalent of the common cold. It’s also one of the most common bacterial infections affecting backyard chickens in the southeastern United States and in California

Typically, chickens are not prone to coryza until they are 3 to 4 months old, and as they age, their vulnerability increases.

Symptoms of Coryza

The main signs of coryza include:

  • Discharge coming from the nose (that smells bad)
  • Sticky eyes that are watery
  • Facial swelling

Because it resembles other respiratory illnesses and frequently occurs in conjunction with them, the disease can be challenging to diagnose. However, a pretty clear sign that the illness is coryza is the nasty smell of the nasal discharge.

Transmission of Coryza

Similar to how the common cold is spread, coryza is also transmitted through respiratory secretions from infected chickens’ coughs and sneezes.

Unfortunately, even if they never had any symptoms, survivors of the disease continue to be carriers. So, by unintentionally bringing a carrier into an existing flock, Coryza can easily be introduced.

Fortunately, hatching eggs from a hen infected with coryza will not be affected. Therefore, providing you take great care to grow the chicks in an uncontaminated environment, it is possible to preserve a flock’s genetics by incubating eggs from diseased breeders.

Treatment for Coryza

Although a vaccine is available, it should only be administered to stop outbreaks after coryza has been identified. Once vaccinated, chickens must continue to receive booster shots twice a year.

Coryza can also be treated using sulfa drugs (sulfonamides).

However, if infectious coryza has spread across a flock, there is only one way to eradicate the area of the disease:

  1. Cull the chickens
  2. Disinfect the facility
  3. Before introducing new chickens, allow the facility to remain empty for at least 3 weeks.