Megabacteria (A Fungus)

Megabacteria, as the name implies, are very large rod shaped organisms. Although initially considered to be a type of bacteria, newly emerging evidence suggests it is really a fungus. Megabacteria have been identified in many species of birds among which include budgies, finches, canaries, lovebirds, cockatiels, rosellas, cockatoos, mynahs, certain parrot species and waterfowl. It has been identified in wild birds as well.Megabacteria are found in the digestive tract in the proventriculus (glandular stomach) and the isthmus or junctional zone between the proventriculus and the ventriculus (gizzard). The mode of transmission is thought to be oral ingestion of infected feces.

Controversy exists as to whether megabacteria are pathogenic or disease causing. In certain species – such as parakeets and canaries – they are often considered as the causative agent of disease, producing a “going light” syndrome characteristic of emaciation. Some birds may harbor megabacteria without showing clinical evidence of disease. Others may be stressed due to systemic illness, poor nutrition or reproductive pressures allowing megabacteria to come in as secondary invaders causing disease.

Two disease syndromes can be seen with megabacteria. Budgies can develop an acute form in which seemingly healthy birds become depressed, puffed up, and die within several hours. These birds may regurgitate blood prior to their death.

A chronic form has also been described in which the bird loses weight despite eating. The course of the disease waxes and wanes but ultimately leads to death. These birds often are ruffled, regurgitate and pass undigested food in their feces.

Diagnosis in a live bird may be difficult as the megabacteria are not always shed in the feces. If present they can be identified by microscopic exam of fresh feces. Failure to find the organism does not rule out infection – since shedding only takes place at certain stages of the disease and may be intermittently shed. Bloods may show anemia and a low total protein.

Barium studies may reveal a dilation of the proventriculus and a constriction of barium at the isthmus.

Autopsy of birds that have died from megabacteria demonstrate an emaciated bird with an empty crop. The proventriculus may be distended with seeds and a white mucoid secretion often is found lining the proventriculus. Ulcers and hemorrhage are frequently found in the proventriculus and the isthmus.

Treatment may or may not be successful. Many antimicrobials do not work. The highest degree of success has been achieved by employing an antifungal known as amphoteracin B orally. Lowering the ph (or making the stomach more acid) by administering vinegar and Lactobacillus also appears advantageous since the organism thrives in a higher ph (basic) envrionment.