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Circovirus: Fear
vs. Fiction
Dave J. Rupiper DVM
Kenneth T. Briggs DVM, Ph.D.
Reports of flocks infected with Circovirus are occurring more and more often. What
steps should be taken to protect your birds?
At least two other Circoviruses exist that affect birds. Psittacine Beak and Feather
Disease and Chicken Anemia Agent are circoviruses affecting parrots and chickens,
respectively. Pigeon Circovirus is different from these two diseases but does show
some similarities.1
Pigeons most often affected are usually squabs and young birds. Mortality is quite
variable with squabs in one flock all dying but other flocks have exhibited no deaths
at all. Infections in young birds are also variable. In a flock of 80 young birds,
all showed signs of the disease whereas some lofts known to have Circovirus present
have had no ill effects in any pigeons.1 Circovirus seems to affect the pigeon's
immune system to make the bird more susceptible to secondary infections like Canker,
Herpes virus, bacterial infections and Paramyxovirus. Consequently, symptoms of Circovirus
resemble these diseases or it mimics a loft which is consequently plagued with problems.
Diagnosis of Circovirus can be extremely difficult since secondary diseases may mask
the underlying cause. Currently, the only way a loft can be diagnosed with Circovirus
is to have a young affected bird necropsied. Post-mortem examinations on adult pigeons
do not yield conclusive results for Circovirus since the bursa, the organ most affected
by the virus, is present only in juvenile pigeons. Occasionally, the spleen will
also be damaged. To date, there are no commercially available tests to diagnose Circovirus
in live pigeons.
Controlling the disease may be hard since it is difficult to diagnose and recognize.
Since the virus affects young birds, ceasing production for one year would help control
deaths but since adults may be carriers, the virus may pop up the next time squabs
and young birds are in the loft. In some regions, it seems affected aviaries are
those which fanciers have been trafficking pigeons without observing routine quarantine
procedures.
The environmental stability of pigeon Circovirus is unknown but is should be similar
to Chicken Anemia Agent. This virus is stable when treated by heating, with detergents
and also with commercial disinfectants.2
In summary, .....
References
1.Woods LW. Circovirus Infections in Pigeons. Proc Annu Conf Assoc Avian Vet, 1993;
156-157.
2.Gerlach H. Viruses. In Ritchie B, Harrison GJ, Harrison LR, (eds.). Avian
Medicine: Principles and Application. Lake Worth, FL, Wingers Publishing, 1994; 862-948.
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