COVID-19 has understandably dominated the news for most of 2020. While this particular strain, only identified in 2019, is relatively new, another coronavirus has preoccupied poultry keepers for years, decimating chicken flocks around the globe.
Better known as infectious bronchitis, chicken coronavirus is highly contagious and affects both adult and young birds. Read on to learn more about this lethal illness so you can recognize it should it strike your henhouse.
The signs of infectious bronchitis differ depending on the age of the afflicted chicken.
Mature layers experience a drastic decrease in egg production. You’ll see an approximate 50 percent drop, states R.M. Fulton, DVM, PhD of Michigan State University’s Veterinary Diagnostic Laboratory and a Diplomate of the American College of Poultry Veterinarians. Eggs lain tend to be severely misshapen with very thin whites.
Furthermore, a hen infected with infectious bronchitis during the first two weeks of life will develop Blind Layer Syndrome, in which her oviduct is either partially or completely absent.
A blind layer will still ovulate, but the ova pass into her body cavity. This causes her to have a swollen, droopy, fluid-filled abdomen and a waddling gait.
In young chickens, coronavirus has more recognizable respiratory symptoms: cough, mucus and rattling/clicking in the throat.
Although the symptoms of chicken coronavirus are visually recognizable, the damage caused by the disease is far more extensive. But it tends to go unnoticed until a post-mortem examination.
A necropsy of an infectious bronchitis-infected bird typically shows blood-engorged vessels in the lower third of the trachea as well as accumulation of tracheal mucus. This makes it extremely difficult for the bird to breathe.
Several strains of coronavirus affect the kidneys, causing them to become pale and enlarged. Uroliths, or bladder stones, tend to accompany these nephropathogenic strains.
Gross lesions are frequently found in both the respiratory tract and oviduct. And the chicken’s nasal passages and sinus cavities commonly contain a liquid, phlegmy or cheeselike substance.
According to Dr. Fulton, younger birds suffering from infectious bronchitis usually die from secondary bacterial infection. Confirmation typically occurs during the post-mortem exam.
A medical determination of whether a chicken is infected with coronavirus is indeed possible.
Diagnosis of blood serum from an infected or convalescent bird happens one of two ways:
- Neutralizing any virus present with antibodies
- Making millions of copies of the sample—a polymerase chain reaction (PCR)—in order to study it in detail and thus isolate the virus
State and university veterinary diagnostic laboratories can perform these diagnostic tests. But the cost may be prohibitive.
A vaccine for infectious bronchitis does exist for chickens. This vaccine is often combined with the vaccine for Newcastle disease.
Dr. Fulton notes that administration of the coronavirus vaccine should occur at one day of age for meat chicks and, egg-laying pullets, at two to three weeks of age, with a booster every two to three weeks.
Once a pullet or hen is in lay, she should receive a live booster every six to eight weeks. While this sounds simple enough, a hitch does exist.
“At present, there are 10 recognized serogroups (strains), with little cross protection between groups,” notes Dr. Fulton.
In other words, a hen who has recovered from, say, the Mass/Conn coronavirus serogroup is not automatically immune to the Ark 99 coronavirus serogroup. Providing a booster containing a different strain of coronavirus can result in the bird displaying symptoms of the newly introduced strain.
Given that infectious bronchitis is one of the most contagious diseases affecting poultry around the world, it is crucial to isolate a symptomatic bird as soon as coronavirus is suspected.
As with any virus, there is no cure. Your options are simply to make your bird as comfortable as possible so she can recover on her own or to cull the sick bird. Once your chicken has recuperated from infectious bronchitis, she will still need to remain in isolation to protect the rest of your flock.
“Recovered birds may harbor the virus for months,” states Dr. Fulton.
Practicing proper biosecurity—including thoroughly washing your hands with soap and water after handling your birds and designating a set of clothing and footwear for chicken-keeping use only—will go a long way toward keeping your birds and you healthy.