Infectious Bronchitis

Infectious Bronchitis, short IB, is also a highly contagious and an acute viral infection. It is caused by the coronavirus, which is able to change its antigenicity. This means that there is not only one but several types of antigen, which can make identification of the type difficult.

The coronaviruses, from the Coronaviridae family, preferentially attack the ephithelial cells of the chicken airways, such as the gastrointestinal tract, the laying intestine and the kidneys.

The Infectious Bronchitis virus (IBV) is the largest RNA virus to date.


The IIP is transmitted through the air from one infected chicken to the next. The resistance of this virus is quite low, but a single vire is all the more contagious. As with other viral diseases of chickens, infectious bronchitis can also be transmitted by equipment, egg cartons and drinking water. The pathogens are absorbed through the mucous membranes or the upper respiratory tract. Once a chicken is infected, the rest of the chicken population can fall ill within 48 hours. This shows how important it is to act quickly in case of infection by IB and emphasizes how important vaccination can be for chickens against various viral infections.

The infectious bronchitis for chickens has an extraordinarily high incidence of symptoms, which often makes it difficult to diagnose the exact disease. As in many viral diseases, like Egg Drop Syndrome, Infectious Laryngotracheitis or Rhinotracheitis, the following symptoms in regard to the egg laying can be:

  • Reduced laying performance
  • Deformed and thin eggshells
  • Discoloured brown eggs

At the IB, too, chicks up to 6 weeks are the most frequently affected. The average mortality rate (morbidity) is 25%. In case of symptoms such as a lack of appetite, an increased need for warmth or developmental disorders, a veterinarian should be consulted as soon as possible.

General symptoms of infectious bronchitis in chickens, besides a reduction of the laying activity, include:

  • Audible breathing sounds and open beak breathing
  • Cough, rattle, sneeze
  • Nasal discharge and clogged eyes
  • Aqueous protein
  • bad breeding and hatching results
  • Fatigue/apathy
  • Diarrhoea
  • Kidney damage
  • Damage to the laying apparatus
  • Muscle damage
  • Deaths due to suffocation, exhaustion or malnutrition

The course of the disease is more or less serious depending on age and general health. If one is not sure about the diagnosis due to the many types of symptoms, a PCR test or serology can help to detect antibodies.

The incubation period of infectious bronchitis in chickens is usually between 18 and 36 hours, but it can also take six days for a chicken to show symptoms.


Once a diagnosis has been confirmed by a serological or virological examination, only the symptoms can be treated and infections caused by secondary diseases can be prevented. Infectious bronchitis in chickens will not be cured and apparently healthy chickens will remain a permanent carrier of the pathogen for the rest of their lives.

In the end, it is only recommended that all chickens be examined, the infected animals removed from the herd and the entire barn disinfected. All common, fat-soluble disinfectants (chloroform) are suitable for cleaning the stables.


In addition to vaccination as a prophylaxis with live vaccines, which are administered via drinking water, it is always advisable to remember to have newly acquired chickens carefully examined and to ensure adequate barn hygiene.

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