Aspergillosis In Birds

Aspergillosis In Birds

Written By: text_none_author Published In: Bird-Blog Created Date: 2016-10-17 Hits: 1943 Comment: 0

What is aspergillosis and what causes it?
Aspergillosis is a respiratory disease of birds caused by the fungus Aspergillus, which is found almost everywhere in the environment. Aspergillosis fumigatus is the most common species of the fungus to cause disease, although Aspergillus flavus, Aspergillus niger, and others can also cause problems. Aspergillus grows readily in warm and moist environments. The microscopic spores of the fungus become airborne, and poor ventilation, poor sanitation, dusty conditions, and close confinement increase the chance of the spores will be inhaled.
Usually, the fungus does not cause disease, however, if a bird does not have a healthy immune system, it can cause illness. Predisposing factors include other illnesses, stress, poor nutrition, poor husbandry or unsanitary conditions, another injury to the respiratory system (e.g.; smoke inhalation), and prolonged use of certain medications such as antibiotics or corticosteroids. The combination of the number of spores in the environment and the presence of predisposing factors determine which birds are most at risk of disease. Aspergillosis appears to be more common in parrots and mynahs than other pet birds.

Symptoms: Symptoms range from respiratory distress, gasping, accelerated breathing, voice changes, abnormal droppings, emaciation, regurgitation, poor appetite, diarrhea, anorexia, gout, increased thirst, nasal discharge, conjunctivitis, dyspnea, neuromuscular disease, somnolence, lesions (yellow or gray nodules and/or plaques in the lungs, air sacs, or trachea; less often in the peritoneal cavity, liver or other sites).

Diagnosis: Tentative diagnosis can be made with clinical signs along with the absence of bacterial infection. A blood test showing an elevation in white blood cell count, mild anemia, and an elevation in the monocytes also supports this diagnosis. X-rays can be taken on any suspect patient. A radiograph can reveal densities or nodules consistent with aspergillomas. Samples of the fungus can also be taken, and cultured in specially prepared culture media. Caution - Apergillus is a common environmental contaminant.

Can Aspergillosis be Treated?
Yes.  Aspergillosis can be treated with a combination of anti-fungal medication and supportive care with variable success depending on the severity and extent of disease. When considering prognosis it should be kept in mind that by the time many birds show clinical signs they likely have been sick for several weeks.
Anti-fungal medication is the first line of defense against aspergillosis, and of these medications, itraconazole is probably the most widely accepted anti-fungal drug. This medication is given by mouth and is relatively safe for use in birds. Another anti-fungal, amphotericin B, has been commonly used as a primary treatment for aspergillosis in birds when they are hospitalized, but it has been known to cause toxicity, damaging the kidneys when used for long periods. Another use for this drug is that it may be administered topically to an area of fungal growth during the endoscopic procedure, as mentioned above. There are many other anti-fungal medications that are used less frequently with varying success. Nebulization (aerosolization) of certain drugs may also be a reasonable way to treat fungal infection by allowing the drug to gain access to the airways. Anti-fungal therapy may need to be continued for at least 6 weeks and in some cases as long as 6 months in order to be fully effective.
In serious cases, surgical intervention may be necessary. Aspergillus can form granulomas (masses of fungi combined with inflammatory cells) within the airways or other parts of the body. If a granuloma forms within the trachea, it can block air flow. If this happens, the animal may need to be anesthetized so that the mass can be removed. If an airway cannot be established, veterinarians will often place an air-sac cannula (a tube leading into an air sac through the body wall) so that the bird can breathe. In many respects this is similar to the placement of a tracheostomy tube as performed in people and other mammals in emergency settings.  Anesthesia of a bird with respiratory problems does carry its risks but it may be necessary if the bird cannot breathe effectively.
Aside from treating the disease itself, efforts must also be made to ensure that the bird is otherwise stable. Because of this, supportive care is an important part of treatment. Some birds may need supplemental nutrition if they are not eating. Other problems such as dehydration or hypothermia may also need to be addressed.  Lastly, it is extremely important to remember that development of aspergillosis is often an indication of an underlying disease or husbandry problem. The cause of immune suppression must be addressed in order to increase the likelihood that your bird will return to health.

Can Aspergillosis be Transmitted to Humans?
Aspergillosis is not considered to be a contagious disease and a healthy person does not need to worry about becoming infected. Aspergillus spores are in the environment and will likely be breathed in at some point, but they rarely cause disease. One exception may be in people who have severe immune compromise. As with birds, the best way to decrease exposure to Aspergillus spores is to keep a clean home in order to limit the inhalation of fungal spores.