Aspergillosis

Paul M. Gibbons, DVM

Niles Animal Hospital and Bird Medical Center

7278 Niles Milwaukee Avenue

Niles, Illinois 60714

(847) 647-9325

Aspergiliosis in birds is an infection by a mold found in the air, in the soil, in animal feeds, and especially in animal bedding. In nature, this fungus derives its nutrition from decaying plant and animal materiaL Aspergillus is considered infectious, capable of growing inside a living animal. It is generally not considered contagious, however, since most birds pick it tq from their environment. The mold is known as an opportunistic invader, causing disease only under special circumstances.

Infection generally occurs when the bird inhales airborne mold spores. If this inhaled dose is high enough to overwhelm the immune system, the bird becomes ill. A bird with a weakened immune system does not require a very high dose of spores. Stressors such as a new cage, moving to a new home, boarding, or a new pet in the home can suppress the immune system. Prolonged illness, traumatic injuries, smoke inhalation (cigarettes), and treatment with immunosuppressive drugs will also lead to immunocompromise. Nutrition is paramount in preventing illnesses such as aspergillosis. An inadequate dietary level of vitamin A will cause a change in the mucus membranes and respiratory tract lining, weakening the front line of defense against infection. Deficient levels of zinc, vitamin C, vitamin E B vitamins in the body can lead to an inadequate immune response and reduce resistance to disease. Finally, when antibiotics are not used properly, or if they are given for an extended period of time, the defenses against aspergillosis wane.

Two forms of aspergillosis are recognized, namely the acute form and the chronic form. The acute form is uncommon, and is usually found in wild birds or pets kept under unsamtary conditions. It occurs following exposure to an overwhelming number of mold spores, such as when ground corn cobs get wet and moldy. The lungs and airsacs are rapidly colonized by a massive amount of mold. With this form a bird might lose its appetite, drink excessively, urinate excessively, have difficulty breathing, or exhibit a bluish discoloration to the skin. It could die without any sign of illness. The chronic form, on the other hand, is more common. These birds have a weakened immune system, and the infection can even enter the bloodstream where it travels to other organs. Birds that are chronically infected with Aspeigillus show a variety of respiratory signs, including a ninny nose, swollen face, inability to exercise, respiratory click, or a reluctance to talk or vocalize. They may have a lack of appetite and lose weight. Birds might have diarrhea or increased urination. Often birds with chronic aspergillosis are depressed and lethargic. (3teen discoloration of the urates can occur, and some birds behave strangely or even have seizures.

When a veterinarian suspects that your bird might have aspergillosis, a variety of diagnostic tests may be employed to establish a diagnosis. The white blood cell count is frequently elevated, and enzymes may be released from tissues damaged by the infection. Some birds become anemic. Radiographs (IX-rays) can show the location of abscesses, changes in the

respiratory tract, or other signs of disease. An examination through the lenses of a rigid endoscope will allow direct visualization of the airsacs and abdominal organs, and w$provide the opportunity to collect biopsy samples for culture and microscopic analysis. In recent years, accurate tests have been developed to detect the presence of Aspergillus in the bloodstream, and the immune response to it. Inflammatory proteins can also be evaluated in the blood, giving further evidence that the bird is fighting infection.

Once the diagnosis is confirmed, treatment is initiated to begin control of the fingus. In the initial stages, nursing care may be the most important part of treatment. Sick birds require warmth humidity, proper nutrition, and plenty of fluids. Medications target the fimgal infection, but often antibiotics are also used to fight or prevent concomitant bacterial infections that are common in these patients. Nebuflzation is sometimes used to humidiI~r the airways and deliver topical doses of medicine deep into the respiratory system. Treatment can include surgery to debride and cleanse the areas where pus, fingus, and debris have collected. In most cases, medications must be given for several months since it is the birds immune system that is responsible for cleanup while the medications simply hold infection in check.

In order to protect a bird from infection by Aspergilius, it is important to keep stressors to a minimum. Birds do well when they are brought up learning that changes are a noniial part of life, and when the home environment provides clear, consistent, loving guidelines. Of course, proper nutrition is key to the health of all animals. A varied diet based on a high quality pelleted ration is recommended. Birds eating this way get sick less frequently than those on seed based diets. Since the Aspergillus fungus grows readily in moist, dirty environments, one must provide good ventilation and keep the cage and surrounding area very clean For veterinanans, one way to prevent infection is to routinely prescribe antiThngal agents when avian patients are on extended courses of antibiotics or are otherwise immunocotuproinised.

At Niles Animal Hospital and Bird Medical Center, we have a very good success rate in treating birds with the chronic form of aspergillasis. It is important, however to obtain a diagnosis and begin treatment as early in the course of disease as possible. Oncethe infection has progressed, it can be very difficult, if not impossible, to return a bird to health. Some birds do relapse, too, giving the tbngus another opportunity to takc their life.