Infectious Coryza


Infectious Coryza

Infectious Coryza is a really, really, bad cold that chickens, pheasants, and guineas can catch.  It is an upper respiratory infection with lots snot and mucus.  Caused by the bacteria Haemophilus paragallinarum, it occurs mostly in flocks that tend to be self perpetuating rather than commercial flocks where the entire flock periodically are replaced.  Once a bird has survived the disease it is not likely to become re-infected but it is a carrier of the disease for the rest of its life.  It is highly contagious but the mortality will be less than 20 % if secondary infections do not set in.   The bacteria is spread mostly through nasal discharge with an incubation period of one to three days followed by the sudden disease lasting around ten days.  The bacteria is hardy and can survive for several days outside a host but is easy to kill using heat, drying and disinfectants.   

Symptoms include facial swelling, eye and nasal discharges, swollen wattles, sneezing, listlessness, egg production dropping,  and lack of appetite.  The birds don’t like to drink water as much and the head and mouth will have a putrid smell.  As it is a bacterium, streptomycin, Dihydrostrepomycin, sulphonamides, tylosin, erythromycin, and flouroquinolones are useful and effective.    Water based antibiotics are less effective.  Bytril (enrofloxicin) is effective but expensive and available only through vets.  Tylan is an inexpensive antibiotic available over the counter.  Dosage is ¾ of a CC injected into the breast muscle, followed by a second shot in four days if the bird hasn’t fully recovered.

As the disease is more common in multi generational flocks, a policy of all in and all out where possible like meat birds or layers helps.  Two doses of bacterin might reduce the severity of the disease when it hits.  Vaccines are available and the vaccines do provide some cross protection from other strains.

Once the disease has entered a flock it is never eradicated as all surviving birds will be carriers.  New birds brought in will catch the disease and any birds sold or given away will spread the disease to other flocks.  Wild birds visiting your flock’s feeders or waterers will either carry the disease or spread it to other flocks nearby so at the risk of sounding like a broken record a good wild bird proof chicken feeder is an essential, not a luxury.  The most surefire way of eradicating the disease is to kill the entire flock once they have recovered and heavily disinfect the entire coop and surrounding areas.  Scrub and disinfect everything including the ground.  A good coating of whitewash and digging some lime into the ground is a good idea.  Let the building and equipment sit vacant for two months before bringing in new birds from a trusted hatchery.


 Replacing the entire flock isn’t overkill when you consider the inability, or inadvisability, to sell live birds once you know your flock is infected and carriers.  Entire generations of birds to come will have to be treated and they in turn will spread the disease to the next batch.





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