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Introduction:
Mycoplasma infections can cause clinical disease in all
ages of birds. Stress and other infections can activate disease in carrier birds (i.e.
birds with the organism present but which are not 'ill'). The presence of Mycoplasma can
also increase the severity of other diseases that are present in the birds.
It is economically one of the most important
diseases of game birds in the UK and hence every effort needs to be taken to control the
condition.
Signs of
disease:
 Swollen facial sinuses are one of
the most obvious signs of active clinical infection but other signs may include sneezing,
eye discharges and breathing through a partly opened beak. If joints are affected then
birds may be lame and in laying birds disease is associated with reduced egg production.
Just as important however is the effect of other
diseases exacerbating Mycoplasmosis. In these cases disease is more severe and proves
harder to control.
Spread of
disease:
Most forms of Mycoplasmosis seen in game birds can be
spread via the egg as well as by direct contact between birds and via faeces etc. The
congregation of birds around drinkers and feeders provides an ideal opportunity for the
spread of this disease. As the disease can be present in birds that show no clinical
signs, the absence of clinical signs in birds that are caught up before the breeding
season is no guarantee that the birds are Mycoplasma free.
Control of
Mycoplasmosis:
As the disease can be spread via the egg and as
Mycoplasma adversely affects egg production one of the most important times for Mycoplasma
control in game birds is before and during the breeding season. In addition the breeding
season is one of particular stress for the adult birds and so it is a time when they are
particularly vulnerable to infection.
Birds showing clinical signs of disease at catching up
should be rejected from the breeding flock. Infection can be controlled, but not usually
eliminated by a variety of antibiotics and control is greatly improved by good management
as this helps to minimise the stresses affecting the birds. The choice of antibiotic and
the medication schedule will depend on a variety of circumstances and should be decided in
consultation with the owner’s veterinary surgeon. The objective will be to minimise
the amount of infection in the breeding birds during the breeding season. This will ensure
that the levels of infection transmitted via the eggs are also minimal.
There is a vaccine available in this country to control
Mycoplasma gallisepticum in layer pullets. This vaccine is not licensed for use in game
birds and if used would only control the one strain of Mycoplasma. As the vaccine must be
given as a very fine droplet in a spray to be effective - eye drop administration is not
likely to be effective - there are few flocks of game birds in the country where
administration of the vaccine could be done effectively.
Control of disease in rearing birds can also be
achieved by antibiotic treatment. As with the breeding stock good management of rearing
birds will greatly reduce the incidence of this disease. It should be remembered that wild
birds are often carriers of this disease so they should be discouraged from remaining
around the breeding, rearing and release pens.
What to do next:
If you have breeding birds, January is the time to
consult your veterinary surgeon to formulate a Mycoplasma control programme for the new
season. If you buy in chicks or poults for further rearing check what medication the
parent birds have received and ask about their disease status. You should then contact
your veterinary surgeon about two weeks before you take delivery of the birds to discuss
what, if any, action you may need to take when the birds are delivered.
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