Could Coryza be the Cause of Your Clucking and Coughing Chickens?

Avian coryza is a bacterial respiratory disease that appears to have become more common in backyard chickens over the last several years. Because it is highly infectious among poultry and typically doesn’t result in high mortality, coryza is rapidly spreading, making it an important disease to understand as a bird owner:

The Basics of Coryza

Coryza is the short or common name for the Gram-negative bacteria  Avibacterium paragallinarim (formerly called Haemophilus paragallinarum). As you can see, us scientists love our complicated names. There is an “uncomplicated” and “complicated” version of the disease. Big picture, the complicated version causes more disease and reflects a disease process that includes coryza and other infectious diseases such as Mycoplasma and E. coli. In contrast the uncomplicated version results in less severe clinical signs and usually “runs its course” in about two-weeks.… Anyway, from here on out we will just use the term Coryza!

How is Coryza Spread and What are the Clinical Signs?

Coryza is spread through direct contact with infected birds, as well as through contaminated surfaces and equipment. Symptoms of coryza can include:

  • facial edema (aka swelling of the face) and infected swollen eyes with discharge
  • nasal discharge
  • swollen sinuses
  • difficulty breathing
  • decreased appetite
  • reduced egg production (almost 50% in some cases)

Coryza Prevention

While none of these clinical signs are specific to coryza alone, being observant when it comes to identifying any of these clinical signs in your flock is important. The earlier you identify sick birds, the quicker you can focus on quarantine, treatment and prevention.

Coryza is typically spread via sneezing and coughing. In order to reduce the potential for Coryza to spread to your flock here are few basic recommendations:

  1. Quarantine new birds for at least 10 days before integrating them with your flock. If those birds are not healthy do not introduce them to your flock.
  2. Practice good hygiene: Regularly clean and disinfect your coop and equipment to prevent the buildup of bacteria and viruses. Like most bacteria, most disinfectants destroy Coryza. Even though it is not zoonotic (aka it doesn’t affect us) you should also wash your hands thoroughly before and after handling your birds or entering their living area to reduce the potential for Coryza to spread between flocks. Coryza is also sensitive to desiccation and sunlight, so make sure coop bedding is dry, especially around the drinkers.
  3. Making sure your coop has good airflow and good ventilation reduces the risk of transmission of aerosolized bacteria. Good ventilation also prevents buildup of ammonia, moisture, and bacteria in your coop. Add additional ventilation if needed.
  4. Always keep an eye on your birds and look out for any signs of illness. If you notice any sick birds, isolate them immediately and seek veterinary care. The quicker you identify a problem the greater potential for a better outcome.

Treatment of Coryza

Because Coryza is a bacteria, some antibiotics such as Tetracyclines can be effective in treatment. However, it is very important to talk to your veterinarian to get the correct antibiotic or else you may end up just wasting time and money on an ineffective antibiotic and in the process contributing to antimicrobial resistance. However, birds that have recovered from the disease remain carriers of coryza and may occasionally shed the bacteria. While the mortality from coryza is relatively low, it should be noted that the “complicated” version of the bacteria, where coryza and other infections are occurring at the same time can result in high mortality.

Unfortunately, there is not a vaccine that backyard poultry owners can use against coryza, but the tips in this focus on prevention, which is the best use of your time and energy.