Signs of Coryza:

• Clear or grayish mucus discharge from the nose. This can also be accompanied by caking of feed in nostrils or a foul odor.
• Swelling of the face around the eyes and possibly under the chin, sometimes including the wattles.
• Runny eyes and/or bubbly fluid in the eyes. The eyes may be swollen shut.
• Drop in egg production of 5% to 70%.
• Birds usually eat or drink less than usual, and they may have diarrhea.
• Many birds may be sick, but few will die unless other disease agents are present. When other diseases are also present, many birds may die.

How the Disease Is Spread:

Sick or carrier birds can spread the disease to other birds by direct contact, airborne droplets (sneezing, for example), or by contaminating drinking water.

Coryza often is spread to a previously clean flock when an apparently healthy chicken which has recovered from the disease (but is still a carrier) is brought onto the farm. The other birds can become infected in about one to six weeks, but some birds will show signs of the disease in as few as 1-3 days.

Outbreaks can occur in several situations:

• When new ("clean") birds are introduced to a flock that has carriers of the disease.
• When new (carrier) birds are mixed with "clean" birds.
• When eggs are hatched on a farm (that has carriers) and the new chicks are exposed to the carrier birds.
• Signs can last for 2-3 weeks, but can last longer if other diseases are present (for example, mycoplasmosis).
• It may be possible to carry the disease to your flock if you walk on an infected farm or handle infected birds and then work with your own birds.

Control of Coryza:

After an outbreak of coryza, some of the recovered chickens will be carriers of the disease. Carriers cannot be eliminated by use of a drug or vaccine.

The only way to get rid of the disease is to destroy all chickens on the farm. The carcasses must be disposed of in such a way (deep burial or burning, for example,) that scavengers don’t spread the disease. The buildings and equipment should be cleaned with soap or detergent and disinfected. No more chickens should be brought onto the farm for 2-3 weeks.

While the frequency and severity of the disease can be reduced by vaccination or antibiotic treatment, the flock will still have disease outbreaks periodically. Any bird from an infected flock which is taken to another farm, market, or fair will probably infect other birds.

Prevention of Coryza:

The only way to prevent the disease is to not buy or handle infected birds. While there is never a guarantee of freedom from disease, buying one-day old chicks from an NPIP (National Poultry Improvement Plan) certified flock is the safest route. It is best to avoid buying chicks which have been on the ground or around older poultry since they could have been exposed to coryza or many other diseases. Older birds are more likely to be disease carriers. An "all in, all out" farm program is preferred for prevention of disease. This prevents mixing birds of different age groups and allows disinfection of the equipment and buildings between groups of birds.

Summary:

A coryza infected flock will always be prone to disease outbreaks and will always be a threat to other people’s flocks. The best course is to eliminate infected birds, disinfect the farm and buy clean birds.

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