is it and what to do about it?
By Dr. Colin Walker B.Sc. B.V.Sc. M.A.C.V.S (avian health)
The term ‘Young Bird Disease’
refers to a condition where young pigeons, usually in the first few
weeks after weaning become quiet, fluffed, lose weight, develop a
green mucoid diarrhoea and die. The cause is a virus called Circo
‘Young Bird Disease’ is in my mind a poor one and one that I think
should be abandoned. The problem is that it groups a whole lot of
diseases that cause similar symptoms into a single category. As the
way these diseases are caught, transmitted and indeed treated are
different they need to be differentiated. Fanciers run the risk of
seeing any young pigeon with these symptoms and simply putting them
down to ‘Young Bird Disease’ when in fact all he is acknowledging is
that the young pigeon is sick with wasting and diarrhoea.
Coccidiosis, Adeno-coli syndrome, Chlamydia, Salmonella, E.coli,
Herpes virus, thrush, hair worm infection, internal canker,
Aspergillus and many other diseases can all cause similar symptoms.
A much better term which actually states the true nature of the
infection would be Pigeon Circo Virus Disease, so that instead of a
fancier saying his pigeon had ‘Young Bird Disease’, the fancier
would say, after an accurate diagnosis that his pigeons had Pigeon
Circo Virus Disease.
is an infectious transmittable virus that spreads from one bird to
another. The virus is shed in droppings, tears, saliva and possibly
also feather debris.
Once in the
loft it can be assumed that every pigeon will be exposed to the
virus and that the vast majority will actually become infected.
Typically however only about 5% actually show symptoms, while the
other 95% although infected with the virus do not develop clinical
symptoms i.e. do not become sick. If tested at this time, they will
return a positive result and are infected, but look completely
normal sitting on the perch.
do become sick develop the typical symptoms of weight loss,
lethargy, diarrhoea and some will develop yellow scum in the mouth.
These birds almost invariably die. The ones that do not become sick
after a period of time clear the virus from their system. We do not
currently know how long this takes but it is thought that the
majority will clear the virus from their system in about 4 to 6
months. There is the possibility however, that some birds will fail
to clear the virus and remain as persistent carriers.
significance of Circo virus infection is that while the virus is
active in the bird it interferes with the functioning of the immune
system. Specifically it targets a particular type of white blood
cell called the T lymphocyte. This means that the pigeons ability to
resist other infections is compromised while the virus is active.
For this reason in some parts of the world Pigeon Circo Virus is
called pigeon AIDS.
alerts us to a Circo virus infection is an increased incidence of
these secondary diseases. If your birds are experiencing a higher
level of canker or eye colds than normal or if the problem quickly
comes back after treatment it may be that Circo virus is the
underlying cause. When disease proves difficult to control or
behaves in an unpredictable manner it’s always worthwhile asking
your vet to check for a concurrent Circo virus infection.
when Circo virus gets into a loft there are two waves of loss. The
first of these occurs when the virus first enters and works its way
through the loft. As mentioned earlier, about 5% of the birds will
be lost. As the weeks role by after the last death it is easy for
the fancier, who has not been to a vet, to think that the problem is
now past. In fact all of the surviving birds in his loft, which may
look completely normal are now infected with the virus and until
they throw the virus off in a couple of months, have an impaired
immune system and increased vulnerability to secondary disease.
Typically these secondary diseases are wet canker and Chlamydia
(respiratory infection) although they can be any disease. Pigeons
rely on exposure to a whole range of potential disease causing
organisms during growth including these two to develop a good
natural immunity. If Circo virus is active this immunity comes, but
takes much longer. This is where the second wave of loss occurs.
Fanciers who fail to identify and manage these problems tend to
loose a lot of pigeons tossing and in the early races. Its not that
the pigeons are not any good, its just that too much is being asked
of them. If they were ‘nursed’ along until a bit older and any
secondary diseases monitored and treated as required many of these
lost young birds would go on a make good race birds.
the Disease Get Into the Loft?
virus enters with a young bird deliberately entered from another
loft where Circo virus is active. Remember that 95% of young birds
in an infected loft do not show any symptoms, and so this introduced
youngster does not have to look sick or in fact ever get sick. It
will however shed the virus and infect other birds for several
months until it, like the majority of birds, clears the virus from
the Disease Diagnosed?
It is very
easy. The disease can be diagnosed from a single drop of blood. In
Australia test kits are mailed to fanciers. All the fancier does is
prick the birds toe, just above the claw. When a drop of blood oozes
onto the skin it is wiped off with a thin strip of supplied
blotting-type paper and placed into a small cliplock plastic test
tube. This is then mailed to the vet for testing. Once collected the
sample is good for weeks, and so there is no problem if it takes a
couple of days for the sample to reach its destination. The test is
called a PCR and checks for Circo virus DNA in the birds’ blood. It
is very accurate and in Australia costs the equivalent of 25 pounds
or US$50. Of interest, Chlamydia infection can also be checked from
the same sample.
can also be diagnosed through microscopic examination of tissues
collected during an autopsy. Here, the tissues are stained so that
the virus can actually be seen. In other birds including parrots a
HI/HA blood test is also available that tests for viral protein and
also the amount of immunity already formed by that bird.
do if Your Birds have ‘Young Bird Disease’ i.e. Circo virus
thing to do is accurately establish the diagnosis. This means
contacting the vet. If you have several young birds become sick,
don’t assume a diagnosis. The problem may be Circo virus or it may
be one of the other problems mentioned earlier. Don’t rely on the
old guy down at the club or your neighbour who also races pigeons.
They don’t have the diagnostic testing available and this simply
wastes time. Similarly don’t go to the local dog and cat vet. If he
doesn’t do a lot of bird work, he can’t be expected to know and it
is therefore unfair to be critical of him. Go to a qualified avian
vet or a vet with a lot of bird experience. It’s worth mentioning
here that avian birds can be thin on the ground, but you don’t have
to be near one. Phone to have a test kit mailed out to you or
organize to send a live bird to them via courier. 50% of the
thousands of fanciers who use my clinic as their veterinary provider
live more that 50 miles from the clinic.
Do bear in
mind that antibiotics kill bacteria but not viruses. There is no
medication that can be routinely prescribed that directly kills
viruses. This means the infection needs to be brought under control
by other means. In some areas of the world a vaccine for pigeon
Circo virus is available. Where available routine vaccination of 6
week old youngsters is recommended.
do if the problem is diagnosed in your loft
In the face
of an outbreak, where available, all youngsters should be
vaccinated. After this the following 4 point plan is adopted:
sick birds; treat them with a broad spectrum antibiotic e.g.
Baytril 2.5% four drops once daily orally and an anti-canker
drug e.g. Spartix 1 tablet daily. And place an
electrolyte/glucose preparation e.g. Electrolyte P180 in the
water. If the birds fail to respond in a few days, they are
often best eliminated.
minimize viral build up in the loft ensure the loft is regularly
cleaned and kept clean and dry.
the birds as well as you possibly can so that the majority can
mount a good immune response to the virus i.e. ‘fight’ the
disease. This means, no over crowding, a good diet, good
parasite control and treating any secondary diseases identified
probiotics, giving probiotics e.g. ‘Probac’ will decrease the
impact of the disease. This is not a treatment for sick birds
but if a bird is exposed to Circo virus while it is on
probiotics it is that much harder for the virus, or at least an
overwhelming dose of the virus, to infect that bird. I usually
recommend ‘Probac’ be placed in the food or water for 2 weeks
initially and then for 2 to 3 days each week until the virus has
worked its way through the birds i.e. it has been several weeks
since a bird has got sick.
do nothing except provide good care until the start of tossing. Then
have the birds checked i.e. crop flush, fecal smear and Chlamydia
test by a bird vet. Any disease that the bird has not developed a
good immunity against i.e. still detectable should be treated and
controlled so that the second wave of loss is avoided.
Do note that
killing sick birds is not a way of eliminating the disease from the
loft because the majority of infected birds show no symptoms.
can be frustrating to loose 5% of the youngsters, the important
thing to remember is that 90% of the birds in a typical out break do
not die. The team is therefore essentially intact and with correct
management can still go on and win if the birds are good enough.
A good thing is
that it appears that recovered birds do develop a good immunity to
the disease. This has been shown to occur with Circo virus (a
different but related virus) in parrots. It also appears that this
immunity can be passed through the crop milk and indeed the egg (the
yolk which is sucked into the abdomen during development, contains
lots of antibodies and hatching chicks also gulp and swallow some of
the egg white (which also contains immunoglobins) which coats the
lining of the bowel). Because of these and other factors the effect
of the virus dramatically reduces each year.