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The Budgerigar Council of Victoria Inc (A10055P) |
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The Budgerigar Council of Victoria Inc (A10055P) |
| "BUDGIE NEWS"
FEBRUARY, 1989.
Coutesty Hans Jarosch Nestling disease in Budgerigars is an acute infectious disease caused by a
virus from the Papovavirus group. 1. Nestling disease in Budgerigars.The causative virus is a small virus without an envelope that is very resistant and infectious for long periods of time not only in the environment, but also in the bird room or aviary as well as on cages and equipment. It survives temperatures of 56°C for several hours and cannot be killed with common disinfectants. For disinfecting, substances containing iodine or a combination of several "aldehydes" as their active agents are recommended. However, when using substances containing iodine it is important not to treat anything containing calcium since they are inactivated. These substances must be left to work for at least two hours in order to be effective. Such exposure time is not possible on the walls of the bird room or on non concrete or aviary floors. Under these circumstances it is advisable to treat the floor with a blowtorch, taking the necessary precautions, and ensuring that this method is not used on plastic coated walls. The virus is extremely infectious. The virus may cause acute disease in nestlings whilst, although older birds and breeding pairs do not usually fall ill, they harbour and excrete the virus. The virus grows in epithelial cells (these are the cells that form the actual surface of the skin and mucous membranes as well as the kidney tubules). This means that the virus may be transmitted to the chicken with the contents of the breeding pairs crop when feeding, or may reach the droppings from the urine to infect the food and water. The third, possibly most important, transmission route is via infected dust to the respiratory apparatus. The virus develops in the skin and the young feather shafts, and is released into the air with feather powder and small scales of skin. The nestlings can hardly avoid infection once the virus is present in the stock. However, the different virus strains differ in their ability to cause disease with the result that the number of deaths varies from a few isolated cases to over 90%. Nevertheless, the same disease process in the nestlings appears to occur in all cases. The virus multiplies at the site of entry (lung, beak cavity or crop) where it is released into the circulation to be transported all over the body where it infects susceptible cells. The extent of tissue damage to the inner organs, with or without the death of the animal depends on the severity of this generalized infection. The virus also almost completely inhibits those cells that produce the necessary substances for specific defence against the infection (antibodies) . If the nestlings survive the acute infection, the virus may multiply in the growing feathers which are consequently ruined, i.e. they fall out or are deformed. The incubation time (the time that elapses between infection and the onset of visible signs of illness) for nestlings is 10 - 21 days (calculated from the day the chicks hatch). Affected nestlings have a swollen abdomen, severe signs of dehydration (particularly visible in the legs and feet which appear to have shrivelled) and fouling of the cloacal region, more with whitish urine than with droppings. When compared with healthy nestlings they show retarded growth of the contour and primary feathers or deformation of the down feathers. This explains why surviving Budgerigars may become runners. The autopsy f indings are not as consistent as the clinical picture since they are often influenced by secondary infections, e.g. by E. coli or flagellates (single- celled organisms with long whip like organelles of motility). The skin is coloured reddish or bluish; the crop is often still well filled this may be regarded as a sign of sudden death. After opening the bird's body the enlarged heart can be seen lying in the heart sac which is filled with fluid. The liver is swollen and shows pale, foci (localized areas of disease) which usually consist of dead tissue. As a rule the kidneys are coloured blackish red and are swollen. The diagnosis is confirmed by histopathological examination or by demonstrating the virus. Serological, i.e. blood tests are possible for identifying birds carrying the virus. The disease can be transmitted to other parrots and parakeets. The following species have been proved susceptible to date:
In these species too, only the nestlings fall ill. The incubation time is
extended to 20 - 56 days in parallel with the longer time it takes the chicks to
develop. The signs of disease may also differ from those in Budgerigars. Apart
from acute diseases there are also chronic forms in which the nestlings just
waste away, but they sometimes also recover. Excessive bleeding after plucking a
small feather could be a sign of disease. Amazons may become paralysed shortly
before death. 2. "Runner" problem
During a French moult the bird loses the primary feathers from the wings and
tail and often bleeds profusely because these feathers are still not fully
developed at this time. The remaining plumage looks very rough, and isolated
contour feathers may be deformed. In this form of runner, immature feathers fall
out after every successive moult and, as a rule, the bird is incapable of flying
for the rest of its life. |