Infectious bronchitis
From Poultry Hub
Infectious bronchitis is a highly contagious viral respiratory infection of chickens, however the virus will also infect the urogenital and gastrointestinal tracts. Symptoms include coughing, sneezing and gasping in young birds, loss of appetite, wet litter and a sharp drop in egg production in layers. In chickens under three weeks of age, mortality may be as high as thirty or forty percent. The disease does not cause a significant mortality in birds over five weeks of age. Feed intake decreases sharply and growth is retarded. When infectious bronchitis occurs in a laying flock, production usually drops to near zero within a few days. Four weeks or more may be required before the flock returns to production. Some flocks never regain an economical rate of lay. During an outbreak, small, soft-shelled, irregular-shaped eggs are produced. The symptoms of infectious bronchitis are non-specific and so laboratory tests are required to confirm diagnosis.
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What causes infectious bronchitis?
Infectious bronchitis is caused by a coronavirus. The virus is highly variable and new serotypes continue to appear. The virus dies quickly outside of the host but can spread through the air and can travel considerable distances during an active outbreak. It can also be spread by mechanical means such as on clothing, poultry crates and equipment. The disease is not egg transmitted and the virus will survive for probably no more than one week in the house when poultry are not present. It is easily destroyed by heat and ordinary disinfectants. Classical Australian strains are nephropathogenic (cause kidney damage) and treatment using electrolytes may be beneficial in an outbreak. Insufficient work has been done on antigenic variants in Australia and we have a limited range of vaccines available (all local strains). A variant has recently caused problems in NSW flocks.
Prevention and treatment of infectious bronchitis
When it occurs, the highly contagious nature of the disease generally results in all susceptible birds on the premises becoming infected, often in spite of biosecurity measures such as sanitary or quarantine precautions. These, however, should still be maintained. There is no treatment for this disease. Antibiotics to control secondary infectious may reduce losses. In young chickens it is helpful to increase the brooder temperature and to optimise environmental conditions. Chickens being kept as layers should be vaccinated. Whether broilers should be vaccinated depends upon many operation-specific factors. Numerous vaccines are available commercially. Most of them represent a modified or selected strain of the infectious bronchitis virus. The vaccine used should contain specific virus known to be present in the area. All vaccines contain live virus and those that give the best protection unfortunately can also produce symptoms of the disease. The vaccine virus will spread to other susceptible birds. Vaccine is usually added to the drinking water, but may be dropped into the eye or nostril or used as a spray.
More information can be found in the article: Maximising infectious bronchitis virus vaccine efficacy.
Further information
- Poultry Health Handbook 4th Ed, 1994. L. D. Schwartz, Pennsylvania State University.
See also
- Poultry CRC Project 03-33: Diagnostics and surveillance of infectious bronchitis
- Maximising infectious bronchitis virus vaccine efficacy
- List of avian diseases
- Types of disease
- Disease prevention
- Immune system
External links
- Infectious-bronchitis.com is the first peer reviewed website with a specific focus on Infectious Bronchitis in chickens.
- The Merck Veterinary Manual has a section dedicated to Poultry
- ThePoultrySite.com's Poultry Disease Guide
