Macrorhabdus ornithogaster Infection in Birds

Macrorhabdus ornithogaster Infection in Birds - Symptoms, Causes, Diagnosis, Treatment, Recovery, Management, Cost
Macrorhabdus ornithogaster Infection in Birds - Symptoms, Causes, Diagnosis, Treatment, Recovery, Management, Cost

What is Macrorhabdus ornithogaster Infection?

Megabacteriosis is a serious and significant fungal disease of specific avian species, namely the finches, cockatiels, and budgerigars. Once thought of being a bacterium, research has shown that it is actually a yeast organism which contains a eukaryotic nucleus. This fungus settles within the true stomach and gizzard of birds, which causes a chronic disease. 

Birds which are affected may have gross lesions that are swollen, exhibit hyperemia, or even hemorrhaging. One main characteristic of this disease is a large amount of produced mucus that is regurgitated by the bird, as well as found in the proventricular lumen.

Poultry and other captive bird types, such as psittacine and passerine birds in the home are generally affected. This yeast infection is rod-shaped and can be up to 5 micrometers wide and 70 micrometers long.

Macrorhabdus ornithogaster infection in birds, or megabacteriosis, is a fungal infection that affects specific types of species of birds.

Symptoms of Macrorhabdus ornithogaster Infection in Birds

Symptoms of Macrorhabdus ornithogaster infection may be quite severe and often fatal. If your bird is suffering from this megabacteriosis, symptoms will include:

  • Weakness
  • Emaciation
  • Vomiting
  • Acute hemorrhagic gastritis
  • Lethargy
  • Diarrhea
  • Ruffled plumage
  • Regurgitation
  • Head bobbing
  • Death


There are several different types of fungal infections in birds. These are important to be recognized and treated as early as possible for a better chance at recovery. Other fungal infections include:

  • Aspergillosis
  • Candidiasis
  • Cryptococcosis
  • Rhodotoruliasis
  • Mucormycosis


Causes of Macrorhabdus ornithogaster Infection in Birds

Although the method of the transmission of this infection is unknown, studies are showing it may be spread from infected birds to other birds. Causes may include:

  • Transmitted by fecal to oral route
  • Genetic factors
  • Close contact with other infected birds


Diagnosis of Macrorhabdus ornithogaster Infection in Birds

If you suspect your bird may have M. ornithogaster, contact your veterinarian. He will ask questions pertaining to your bird’s symptoms and how severe they are. He will do a physical examination and take a closer look at his symptoms. 

Laboratory testing will be performed by your veterinarian. Blood work, a biochemistry profile and a fecal sample will all be tested. Anemia may be present in the blood, as well as a decreased number of electrolytes. Changes that appear in the complete blood count may also show infection, as well as an increased pH in the proventriculus. Gram staining will be used in the fecal testing. A technique known as mini-Flotac may also be used to test the fecal matter. Cytology testing of samples from the true stomach, or proventriculus may also be conducted.

Your veterinarian may also perform a radiograph using barium sulfate contrast techniques. This may support a possible megabacteriosis. Lesions may also be present in your bird’s digestive tract, and your veterinarian may test those as well.



Treatment of Macrorhabdus ornithogaster Infection in Birds

If your bird has been diagnosed with M. ornithogaster, he will explain to you his prognosis and outline a treatment plan for him. Treatment methods may include:

Antifungal Medication

Antifungal medication may be prescribed rather than antibiotics. Amphotericin B is typically the drug of choice by many medical professionals. This drug may be given to your bird by mouth, mixed with water, or mixed in food. Nystatin may be also effective when using this drug with affected goldfinches. Both of these medications bind to the fungi cell membranes ergosterols. 

Increasing Acidity

Increasing the acidity of the gastric system may help birds with this condition, as the fungi prefer a more alkaline environment for growth. Your veterinarian may recommend using organic acids, such as vinegar or grapefruit juice, to add to your bird’s water. He may also recommend Lactobacillus spp. to add to your bird’s dietary intake.



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Recovery of Macrorhabdus ornithogaster Infection in Birds

Your veterinarian will explain what you need to do in terms of at-home care and management of your bird. Fortunately, this condition is treatable and birds typically respond to treatment if they are not severely affected and if the treatment protocol is followed. If left untreated, this condition can be fatal.

It is important to reduce any exposure to healthy birds, so the affected bird must be isolated. Keeping the aviary clean and hygienic is also imperative. Your veterinarian will also discuss with you any stressors your bird needs to avoid in order for him to recuperate. It is crucial to listen to your veterinarian’s advice and if you have any questions, witness any new symptoms, or become concerned to contact him. He may want to see your bird again to monitor his health and condition, and to give you advice on how to be sure he recovers properly and how you can keep your other birds well.



Macrorhabdus ornithogaster Infection Questions and Advice from Veterinary Professionals

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