Infectious bronchitis


Infectious bronchitis (IBV) is caused by a virus of the Coronaviridae family. It is highly contagious and affects broilers, breeders and laying hens.

The virus is not contagious to turkeys or wild birds. This virus spreads quickly in a flock between birds. There are multiple serotypes and several may circulate in a region, but in general there is no cross-protection between them. New isolates can be found that can cause disease even in vaccinated birds.

The infectious bronchitis virus is transmitted mainly by the respiratory tract, by aerosol (approximately 1 km) and feces. The virus can persist in birds, the digestive system and feces for several weeks or months. Transmission is horizontal, direct (from sick birds to susceptible birds), and indirect (through water, equipment, clothing, food, transport of birds, any contaminated material, etc.). Stress can promote the onset of the disease and birds can be asymptomatic carriers. There is no evidence of transmission via the egg (vertically).

The infection begins in the respiratory tract, the virus replicates and produces lesions in several types of tissues (respiratory, kidneys and oviduct or testes). The virus can replicate in the oviduct and cause permanent damage in immature females or pullets resulting in limited egg production during their lifetime, with a drop in egg laying of 10-70% and more, but decline in Egg production can be highly variable for at least 6 to 8 weeks, but in some cases peak egg laying before infection is never reached. Eggs may be of poor quality (thin or absent shell, variation in shell pigmentation or rough shell, albumen may be thin and watery (too liquid), deformed eggs). Poor egg quality and shell irregularities can persist long after an episode of infectious bronchitis.

Laying birds affected at a very young age have an atrophied reproductive system and cannot lay eggs. The yolk can detach from the ovarian cluster and end up in the abdomen and cause complications and even mortality in birds which can reach 5% and this can be higher in the presence of secondary infections. Some strains can persist in the oviduct for several days with a peak between 10 and 14 days after infection.

In 2015, the DMV/1639 strain was only detected in the Delmarva Peninsula in the United States, but in 2017 a new serotype appeared in Ontario and it is the Delmarva variant strain (DMV). In Ontario, the disease affected broiler chickens with an increase in condemnations and insufficient weight gain, and some broiler breeder flocks had minor clinical signs (peak mortality, diarrhea, weak shells). The commercial layer sector, which has experienced cases of “false layers”, would have raised the urgency of the situation and the need for solutions, such as a new vaccine.

Infectious bronchitis virus (IBV) – Vaccines available in Canada
Sampling protocol when a case of bronchitis with the DMV type strain is suspected