The disease aspergillosis is caused by a fungus from the genus Aspergilla. Aspergilla has the potential to infect a wide range of mammalian, avian and reptilian species including man and is probably the most common fungal infection found in birds.

The most common species of Aspergilla causing disease in birds are A. fumigatus, A. flavus and A. niger. There are numerous other species of aspergilla present in the environment but these rarely appear as a cause of the disease.

A. flavus has been isolated as a cause of aspergillosis in emus in Queensland.

Aspergilla is widespread throughout the environment and where conditions are suitable it will grow and multiply to give a localised high concentration of the fungus.

In Queensland the disease has only been seen in emus as a rapidly progressing respiratory condition that continues to worsen until the chick dies.

The chicks appear to get infected in the brooder house very early in life. Initially no signs will be seen but gradually affected chicks will appear unthrifty and less active than other chicks in the group and show signs of gasping and respiratory distress if forced to exercise. In the final stages the chick is obviously depressed, doesn't move much and shows laboured respiration which is seen as exaggerated movement of the ribs and chest in and out with each breath, possibly combined with open mouth breathing. This is the terminal stage and usually the chick will die soon after.

These signs are associated with the spores hatching and growing in the lungs. Firm, round, white nodules are formed in the lung tissue and these grow steadily. As they grow they occupy lung space and disrupt the normal functioning of the lung. This decreases the oxygen supply to the chick to the point where it can no longer survive. These nodules can also be found in other sites including the air sacs, attached to the rib cage, the liver and throughout the abdominal cavity.

Aspergillosis has not yet been recorded in Queensland in emus after 12 weeks of age. It has only been seen as an acute respiratory disease in young chicks.

This differs from the ostrich industry where reports indicate that as well as causing problems in chicks, aspergillosis can also infect the air sacs of older birds to cause a chronic debilitating disease.

This is usually done by post-mortem of suspect birds with confirmation coming from specimens sent to a veterinary laboratory.

A blood test has been developed by Murdoch University for use in ostriches, however, I do not know if this test would work with emus. Given the difference in prices, diagnosis in emus is more likely to be done by post-mortem.

There is no known effective treatment for clinically sick birds. A range of treatments has been attempted in the ostrich industry but to date a successful treatment regimen has not been found.

At this stage, prevention is the only effective method of controlling aspergillosis in emus.

Prevention should be aimed at three broad areas:

This would include such things as removing wet litter, not using damp or mouldy straw/hay as litter or food, not using or removing spoiled grain and regular provision of fresh non-dusty litter.

This is an important area as dust in the air of brooder sheds appears closely associated with infection of young chicks.

Dust is most likely to be raised when litter is being removed or raked over. In these cases it would be worth lightly damping down the litter so dust is not raised when it is moved.

Good quality litter will also help. A coarse litter of wood chips or pine wood shavings appears to work well. Litter that is already dusty may only contribute to the problem.

Attention to hygiene can prevent aspergilla numbers building up to a point where problems occur. This needs to be done in all stages to the end of the brooder stage.

Eggs should be fumigated and/or washed in a recognised egg sanitiser used according to directions.

The cold storage room, the incubator and the hatcher should be fumigated or cleaned regularly with a recognised disinfectant active against fungi.

The brooder house should be cleaned and disinfected before the hatching season begins. If individual pens are cleaned out during the breeding season they should be disinfected as well each time.

Disinfectants that are active against aspergilla include those containing gluteraldehyde as an active constituent, Antec Virkon S and Antec Farm Fluid S.

The above procedure will also control other diseases that may cause problems during incubation, hatching and brooding.

In summary, aspergilla has a potential to cause severe problems. Efforts to control this problem should be directed at prevention as there is no effective cure at this point in time.