by Darian Peters

Created on: March 24, 2009

Infectious coryza is a respiratory disease found in many species of birds, including poultry, with chickens being particularly vulnerable to the disease. This bacterial disease has similarities with the common cold and indeed cold is one of its common names. The disease is found worldwide and takes a particular toll on those who are running smaller operations.

The disease is caused by a gram-negative bacterial species called Hemophilus paragallinarum that has three antigenic types that are labelled A to C. The species requires the presence of V factor in order to grow. Incubation of the disease is only a couple of days but infection can last anything from one to three months. Transmission is by contact between birds but could also happen by ingesting contaminated food stuff and water or even via inhalation of infected aerosols or transportation by the clothes of farm workers and the implements found on the farm.

Cold-like symptoms such as coughing and sneezing as well as rotten smelling nasal discharge are to be found in the infected birds. Other symptoms include swelling of the face and lacrimation (watering of the eyes). Typically lethargy will set in and the birds will go off their food and water. The symptoms may be complicated by the presence of other diseases in the birds such as sinusitis and mycoplasma. The mortality rate can be anything up to 50%.

The disease can hang around in carrier birds for a long time and any flock that has the disease is potentially a threat to healthy flocks. Diagnosis can be done by looking at flock history and the symptoms and lesions present. But as so often a definite diagnosis can only be made on the basis of isolating and identifying the organism responsible for the infection. In this case the Hemophilus paragallinarum bacterium.

Preventative measures against the disease include attempting to eradicate the disease causing organism from a flock. This is something that may ultimately require the destruction of any birds that could be infected. But less drastic measures include improving hygeine, disposing of dead birds correctly, and keeping out potential carrier organisms from the flock, for example. Segrogating birds on the basis of age and species also helps, with most infection resulting from mixed flocks. There are also medications available as well. Any one of a variety of sulfonamides can be used, with sulfadimethoxine being the safest one available. Antibiotics such as tetracycline are another possibility.

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