Just like we go through our flu season in late fall through late winter, chickens also go through their version of flu season. Poultry respiratory viruses such as avian influenza, infectious laryngotracheitis and infectious bronchitis (one of the coronaviruses you may see in chickens) are more common in the winter than the summer.
Among other factors, cold and damp conditions seem to help respiratory viruses persist and spread.
This column provides relevant information about infectious bronchitis for your backyard chickens. But itâ€™s also meant to clarify any misconceptions anyone may have about coronaviruses and chickens.
Coronaviruses are ubiquitous in animals (including chickens), and theyâ€™re typically associated with mild respiratory signs. While ubiquitous, they typically â€śstickâ€ť to their species.
In other words, chicken coronaviruses stick to chickens, dog coronaviruses stick to dogs, etc. Very rarely do we have transmission of a virus from one species to another.
Unfortunately, we are currently dealing with a rare situation where a virus (COVID-19) has â€śjumped the species barrierâ€ť to humans from bats and/or pangolins (insect-eating mammals covered in overlapping scales, aka scaly anteaters).
Read more: Another coronavirus? Yes, but it’s a common poultry condition.
Infectious Bronchitis Virus
When chickens get their version of a coronavirus (aka infectious bronchitis), they get many of the same clinical signs of respiratory disease, listed in the sidebar â€śRespiratory Red Flagsâ€ť below. They may additionally have a â€śpuffed upâ€ť appearance and be reluctant to move.
Furthermore, if hens are in lay, theyâ€™ll often have reduced egg production. The shells will look and feel wrinkled, too.
Multiple versions of infectious bronchitis virus are typically identified with names such as â€śDelaware,â€ť â€śCalifornia variant 99â€ť and â€śArkansas type.â€ť This reflects the slightly different genetics of each strain.
Interestingly in the world of chickens, different vaccines exist for the different serotypes of coronaviruses, which reflect these differences. (While COVID-19 has mutated like all living organisms, still one version exists with respect to its serotype.)
It will be interesting to see if eventually COVID-19 mutates enough over time to require multiple vaccine types in humans.
Chickens get infectious bronchitis following inhalation or direct contact with contaminated poultry litter equipment or fomites (nonliving material that can transmit disease). We should also note that the virus can spread between and within poultry flocks as well as by wild birds.
Itâ€™s highly contagious and has a very short incubation time. In 24 to 48 hours, infected chickens begin to show the clinical signs mentioned previously.
Care & Concern
So what do you do when your birds get sick? First, you need to confirm what your chickens have. Unfortunately, this is done via a necropsy (aka an animal autopsy).
You can work with your veterinarian or state animal diagnostic lab to get this done. In many cases, you can have this done for free or for a nominal cost. (For example, in California where I live, the cost is $20.)
Unfortunately, there are no treatments for infectious bronchitis. This is why prevention is so important.
To reduce the risk of your chickens contracting infectious bronchitis and other infectious diseases, you must practice good biosecurity. While there are vaccine options for infectious bronchitis, in general, they donâ€™t work great for reasons beyond the scope of this article.
For this reason and many others, focus on biosecurity.
Make small incremental improvements in fencing, equipment, feed storage. In this way, you can do your part to reduce exposure.
Philosophically, donâ€™t make â€śperfect the enemy of good.â€ť In other words, do the best you can with the resources and husbandry style you have. When in doubt, reach out to your veterinarian and/or friendly cooperative extension specialist regarding any biosecurity questions you may have.
Once infectedâ€”even if part of your flock recoversâ€”your chickens may still be carriers and hence transmit disease to naive chickens. Therefore, if your flock receives a diagnosis for infectious bronchitis, you’ll need to keep your flock quarantined for the remainder of its life.
Read more: Biosecurity will keep your chicken flock healthy.
Human vs. Poultry
Multiple global studies show that chickens and other domestic poultry arenâ€™t susceptible to COVID-19. Transmission of coronaviruses (of which COVID-19 is one of many types) from poultry to humans or vice versa hasnâ€™t been demonstrated.
Poultry-based foods, including eggs and poultry meat, are safe to eat. Regardless, always handle poultry products and all food with good food-safety practices.
Keep in mind that coronaviruses are respiratory viruses transmitted from person to person primarily via the respiratory route. No documented cases exist of virus transmission via an oral inoculation from a contaminated product. (Think of the virus deposited on food by an infected individual.)
This is primarily because coronaviruses are what we call â€śenveloped viruses.â€ť Enveloped viruses are â€świmpyâ€ť when exposed to UV sunlight, heat and disinfectants versus nonenveloped viruses, which are much more difficult to inactivate.
Note: You canâ€™t kill a virus because most biologists donâ€™t consider viruses to be alive or even organisms. As the French biologist and Nobel laureate AndrĂ© Lwoff said in 1962: â€śWhether or not viruses should be regarded as organisms is a matter of taste.â€ť
Based on our historic and emerging knowledge of coronaviruses, the primary route of infection is airborne. Practice good hygiene, husbandry and biosecurity with your poultry. It’s the same in a â€śCOVID worldâ€ť as in a â€śnon-COVID world.â€ť
When it comes to poultry, letâ€™s keep our â€śeyes on the ball.â€ť Focus on the greater risks with respect to food safety, such as salmonella and campylobacter.
Sidebar: Respiratory Red Flags
Keep an eye on your chickens for these common signs of coronaviruses or other respiratory disease:
- gentle rattle coming from the trachea
- reverse sneeze
- sometimes (although more rare) a cough or two
You also might see some irritation and inflammation around the mucus membranes of the eyes. If you think you hear something, pick up the chicken and hold its breast up against your ear. Feel or listen for any abnormal breathing such as rattling.
Itâ€™s also a great idea to do this when you donâ€™t hear anything so you know what normal sounds like. Differentiating normal from abnormal is one of the most essential skills to acquire when diagnosing problems. Itâ€™s not hard but it does take practice and attention to detail.
This article originally appeared in the January/February 2021 issue of Chickens magazine.