What are Cryptococcus neoformans?

Almost all mammals are susceptible to this disease and many start with birds (most often pigeons). The two main species are Cryptococcus neoformans variety neoformans and Cryptococcus neoformans variety gattii with subtypes A, B, C, and D. These may be spread from contact with other birds or from the environment they live in such as eucalyptus trees and other habitats. The spores are breathed into the lungs where they multiply and take over the sinuses and nasal cavity of certain animals although in some cases the spores can be absorbed through the skin. Cryptococcus neoformans is found all over the world but mostly in Europe. Cryptococcus neoformans gattii is fatal, causing pneumonia, heart, and kidney damage.

Cryptococcosis is a fungal disease caused by the infiltration of the Cryptococcus neoformans fungus. Although it was uncommon in birds, it has been found in the fecal matter of birds (most often pigeons, canaries, and psittacine birds) and it can be spread to humans as well. This can be a serious illness in all birds, causing respiratory distress, diarrhea, appetite and weight loss, weakness and central nervous system damage. The CNS damage can affect your bird’s sight and movement, and may be lethal in some cases. It is transmitted through inhalation of the spore or yeast cells.

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Symptoms of Cryptococcus neoformans in Birds

The symptoms your bird has depends on which body part or parts are affected. Some of the most common are:

Respiratory

  • Breathing difficulty
  • Sneezing
  • Coughing
  • Snoring
  • Nasal discharge
  • Eye problems

Central Nervous System

  • Weakness
  • Disorientation
  • Convulsions
  • Depression
  • Paralyzation
  • Dizziness
  • Death

Topical

  • Skin lesions
  • Eye infections
  • Itching
  • Agitation
  • Sores around the nares and beak

Types

  • Cryptococcus neoformans neoformans
  • Cryptococcus neoformans gattii
  • Cryptococcus neoformans subtype A
  • Cryptococcus neoformans subtype B
  • Cryptococcus neoformans subtype C
  • Cryptococcus neoformans subtype D

Causes of Cryptococcus neoformans in Birds

The cause of Cryptococcosis is the inhalation of the spores from one of the Cryptococcus neoformans fungi. Certain breeds are more susceptible to this disease, which include:

  • Canaries
  • Pigeons
  • Psittacine birds (such as parrots, budgerigars, parakeets, cockatiels, and cockatoos)
  • Macaws
  • Sometimes found in chickens, doves, starlings, and sparrows

Diagnosis of Cryptococcus neoformans in Birds

A definitive diagnosis from your veterinarian requires a complete physical examination, diagnostic tests, laboratory tests, and radiographic imaging. Give your veterinarian a thorough description of your bird’s medical history and recent behavioral changes. The physical assessment will include all over auscultation and palpation of all the major muscles and organs, a detailed examination of the entire body, body condition, and vital signs. 

Next, the veterinarian will collect nasal swabs, aspirates, and smears of the affected areas. In addition, a bronchial wash will be done to collect fluid for microscopic examination and skin scrapings are usually examined as well. The veterinarian may use an endoscope to get a look at the respiratory tract, sinuses, and upper airway to check for gelatinous exudate, which is usually visible with Cryptococcosis. Routine blood tests such as a serum biochemistry assessment and complete blood count (CBC) should be able to isolate the Cryptococcus neoformans organisms for a definitive diagnosis. 

However, the veterinarian may also decide to get urine and spinal fluid for histologic and cytologic cultures. Also, there are stains that can be used for isolating the organism such as colloidal iron, Wright’s stain, India Ink, and Alcian blue. Spinal fluid will likely show a mild increase in protein, low glucose, and lymphocytes. Finally, the veterinarian will take some radiographs and an ultrasound to check for involvement of the lungs, liver, kidneys, heart, and brain.

Treatment of Cryptococcus neoformans in Birds

There are several medications used to treat Cryptococcosis and the veterinarian will also need to treat your bird for any additional infections and complications such as lung damage, central nervous system involvement, and kidney problems.

Drugs for Eliminating Cryptococcus Neoformans

Some of the drugs used in treating Cryptococcosis include voriconazole, fluconazole, ketoconazole, itraconazole, and amphotericin B. These are antifungals that have been known to get rid of Cryptococcus neoformans.

Drugs for Infection and Complications

To treat pulmonary or central nervous system infections, antibiotics may be given, such as penicillin, ampicillin, or amoxicillin. Skin lesions are usually treated with antifungal cream or ointment and ocular (eyes) involvement will require antifungal drops or ointment.

Oxygen Therapy

In certain severe pulmonary cases, the veterinarian may also provide oxygen therapy with an oxygen enclosure for a short time until your bird is able to breathe properly. This will include a short hospital stay of about 12 to 24 hours. Steroids are also commonly used in these cases.

Fluid Therapy

If your bird is dehydrated from diarrhea or if there is renal involvement, the veterinarian will most often give intravenous fluids for approximately 12 to 24 hours. This will improve circulation and flush the kidneys.

Recovery of Cryptococcus neoformans in Birds

Because this type of infection is often chronic, you will need to keep a close eye on your pet for several weeks to watch for relapse. Monitor your bird’s eating and toileting habits for changes that could indicate he is unwell. Continue to provide the medication as directed and return to the office to see the veterinarian when instructed.