DR DAVID MADILL
This may be a serious disease in
There are numerous species of coccidia. Eimeria spp and lsospora spp
A wide variety of bird species may he affected, in particular
budgerigars, pigeons and poultry.
The entire coccidia group has basically
similar direct life cycles. The bird is infected by ingestion of a sporulated
oocyst. These hatch in the intestine and undergo a number of asexual
(schizogonous) generations in the small intestine. If the schizonts occur deep
within the mucosa they may cause extensive trauma to that mucosa when they
rupture. Intestinal haemorrhage may
If, however, they parasitize surface epithelial cells, their effect
may be minimal. After undergoing, their schizogonous cycle the parasites
differentiate into male and female forms (micro and macrogarnetocytes
respectively) and undergo a sexual (gametocytic) generation. This phase is
usually considered to be relatively non- pathogenic. The culmination of the
sexual cycle is the production of oocysts which are passed in the faeces,
usually in the non-sporulated form. Exposure to a warm moist environment
facilitates development of the oocyst to its infective form.
Coccidial oocysts have been
identified in the faeces of a wide variety of birds. Each species of coccidia is
generally regarded as being a fairly, host specific parasite, and capable of
infecting only the species of bird from which it was obtained.
passing oocysts may not have clinical signs, stress may result in disease.
Lethargy, weight loss, diarrhoea, dehydration and rapid death are reported.
Birds may show "dirty" vents. In pigeons weight loss, poor performance,
diarrhoea and deaths, especially in young birds, are recorded.
Based on clinical signs and
numbers of oocysts shed. A few oocysts in healthy birds may not indicate a
problem, however, treatment may still be indicated (e.g. budgerigars).
Many birds can carry coccidia
and shed oocysts without any indication of disease. Overcrowding and concurrent
disease can cause a flare up of disease, requiring treatment. Anti-coccidial
drugs can be used to treat infections, and in some cases can be used as
coccidistats if disease flares up as soon as treatment finishes. Baycox (Bayer),
Coccivet (Vetafarm), Toltro (Agrotech Australia Pty Ltd) are all effective.
Trimsul (All Farm Pty Ltd) is also very useful.
Thorough cleaning, maintaining dry
conditions, preventing food and water containers being fouled, must be paramount
at all times.
In thoroughly cleaned aviaries, large numbers of infected
oocysts will not accumulate. If conditions are maintained as dry as possible,
sporulation of oocysts to their infective form is minimized.
The avoidance of
fouled food and water containers ensures that birds will ingest only a minimal
number of oocysts.
It is impossible to prevent exposure of birds to
Continuous infection with small numbers of oocysts results in a
state of immunity. (This does not apply to budgies in an aviary
Maintenance of such an immune state should be the aim. However,
debilitation by other diseases or stress, as well as infection by large numbers
of infective oocysts, may breakdown such immunity, and result in
Strategic treatments may prevent
outbreaks <e.g.: before breeding, after fledgling, after rain or high
Strict quarantining of ALL newly acquired birds is also very
Minimum quarantine period is 6 weeks, and the quarantine facility should
be separate from the main aviary, cleaning and feeding should be done
last each day to avoid cross
infection. Separate feeding and water containers should he used.