This is a disease that has recently ravaged canary aviaries on the east coast, and I suspect may be present in the bird rooms of other breeders across the US. While it affects both genders, it appears to be acutely lethal to females, and will affect productivity. If you or a fellow breeder has noticed a reduction in surviving females from year to year, a sudden drop in fertility, or birds breathing heavily on your bird room (especially noticeable at night) even after treating the flock for airsac mites, you should carefully review and consider the information that follows.

Megabacteria (gastric yeast) are large, gram-positive anaerobic organisms that live in the proventriculus, or the glandular stomach before the gizzard. Since antibiotic testing has proven useless against this organism, yet fungal medications seem to effective, research suggests that these organisms are actually a yeast or fungus and not bacterium. Under the microscope, Megabacteria (Macrorhabdus ornithogaster) look like large blue rods.

Symptoms: Megabacteria is often associated with the "going light" syndrome in budgies. Birds in relatively good condition suddenly become fluffed up, lethargic and severely depressed. Early on, slimy seeds are regurgitated leaving a smear on the face. Occasionally, birds will vomit blood, or will stretch their necks and appear to be gagging. Affected birds may appear to feed frantically, but no food is actually digested. Droppings are dark green to brown/black with very little white urates. Despite the various foods offered, the affected birds will lose body weight and breast muscle. Canaries may exhibit enlarged abdomens as the organism invades the intestines. In acute cases, infected birds may die in a few days; or in chronic cases, birds may become progressively emaciated and die weeks or months after infection. Fecal tests are only up to 80% accurate and false negative results can occur. Diagnosis is best done through a necropsy to accurately detect the presence of Megabacteria.

Transmission: The earliest record of Megabacteria in the United States was in 1982, but it has been a chronic problem outside the US in England, Australia, Germany and Japan. Megabacteria have been identified in the following types of birds so far: canaries, European goldfinches, lovebirds, cockatiels, English budgies, parakeets, rosellas, various cockatoos, finches, ostriches and chickens. According to the literature, 27 to 64 percent of all budgies carry Megabacteria, but exhibit no symptoms. It is possible that this organism is part of the common gut bacteria of certain birds, but then becomes problematic when other diseases break out at the same time. Transmission is not fully understood. Courtship feeding rituals may be a key factor in transmitting the disease. Since fecal spread is a concern, good housekeeping and daily removal of droppings is essential. Also, daily water changes of communal drinkers are recommended.

Treatments: Researchers have tried numerous antibiotics, but none have proven effective at eradicating the disease. Raising the pH of the water by adding organic acids (i.e., apple cider vinegar, white vinegar or grapefruit juice) at 15 cc per liter helps treat the symptoms, but doesn't cure the disease. The fungicides Nystatin B (Nilstat), Ketoconazole (Nizoral), and Amphotericin B have all been tested. To date, only the Amphotericin B has been proven effective at eradicating the disease. Early experimental research treatments involved twice daily crop injections, which were extremely stressful on the affected birds (and the nerves of the bird owners!) Vetafarm in Australia has developed a water-based formulation of Amphotericin B, named Megabac-S, which has been shown to completely eliminate Megabacteria in treated birds three months after treatment. Unfortunately, if the treatment starts too late for an infected bird, the Megabacteria may be cleaned out of its system; however, permanent damage to the proventriculus may result.

Infected birds that have been diagnosed early and treated properly may resume normal lives and regain fertility. The recommended dosage of Megabac-S is 5 grams per liter in the drinking water for 10 days. A fresh solution should be provided daily, and it is best to use light-blocked water bottles to maintain potency of the medicine. Follow the Megabac-S treatment with a 5-day dose of beneficial bacteria (e.g., Lactobaccillus), such as Vetafarm's Probiotic. During treatment, all cages, perches and shared feeders should be kept scrupulously clean, along with daily water and cage paper or bedding changes.

As with any type of disease, treatment is probably most effective during periods of low stress (e.g., avoiding the breeding season or molt). If this disease becomes noticeable immediately preceding the mating season, unpaired birds can be treated at any time, but allow at least 3 weeks before pairing. If the disease hits during the breeding season, mated birds should only be treated at the onset of incubation, since there is a 13-14 day treatment window before the chicks hatch. Once the breeding season is over and all of the chicks have been weaned, repeat the total treatment for all the birds in the aviary at the same time to ensure that no individual has escaped full treatment. If any birds in an affected aviary should die after the treatment is completed, another necropsy is recommended to identify the exact causes of death, and to confirm the absence of the Megabacteria organism.

Prevention: Do not assume that birds are clean, even if gotten from a "reliable" source. Provide total isolation for all newly acquired birds, regardless of source. Veterinarian recommendation is a minimum period of 4 to 8 weeks. Isolation includes not only keeping the new birds entirely out of the aviary, but also changing footwear before entering different holding areas. Also, utensils used to clean drinkers, feeders and cages from different holding areas should be kept separate, or sterilized in a disinfectant solution after daily use. One breeder recommended placing a sheet of wax paper at the bottom of the temporary isolation cage to collect the droppings 1-1/2 weeks after the birds are acquired. (This period of time would allow any birds under previous treatment prior to your acquisition to regain normal function, and not artificially mask any internal disease problems). The fresh droppings should then be taken to an avian vet for full analysis to determine if the birds are harboring any hidden disease or parasite problems. Remember, Megabacteria does not respond to typical bacterial treatments, so providing heavy doses of antibiotics will not stop the spread of this disease; and it may go undetected when new birds are introduced into the aviary.

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