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MEGABACTERIA - A REVIEW OF THE LITERATURE By Claire Talltree, MSW Page 1
MEGABACTERIA
A REVIEW OF THE LITERATURE By Claire Talltree, MSW
Note: no portion of this article shall be reproduced introduced goldfinches in Victoria, Australia, and without the prior consent of the author. some suspect that it has in fact been there a longtime but unrecognized. Megabacteria was recorded in the United States as early as 1982. No one INTRODUCTION
knows where it originated, but it seems to be an As a breeder/exhibitor of budgerigars, I recently ongoing problem in the United Kingdom, Australia, had several birds fluff up and begin to waste away.
United States, Germany, Japan, and probably other Some died immediately; others lingered for months. No one could diagnose the problem until, HOSTS OF MEGABACTERIA
after great expense and several veterinarians later, Megabacteria has been found in both psittacine and Megabacteria was found to be the only pathological passerine species, both in captivity and in the wild.
agent present in my birds. No known treatment was The psittacine species that have tested positive for offered, which led me on a world-wide search of Megabacteria include: budgerigar, African information on the disease. The Internet yielded lovebirds, king parrot, red-wing parrot, sulphur- many resources, including the Association of Avian crested cockatoo, galah, white-tailed and black- Veterinarians -- Australian Chapter, which had tailed black cockatoos, red-crowned kakarikis, addressed the problem at recent conferences. Many Bourke’s parrot, scarlet-chested parrot, cockatiel, researchers were also located; of these the best princess parrot, superb parrot, mulga parrot, Indian assistance came from Dr. Tony Gestier of Vetafarm ring-necked parakeet, and rainbow lorikeet. The Pty. Ltd. in Australia. Following this article is a list passerine species include: European greenfinch, of Web sites and articles that provided me with painted firetail finch, Gouldian finch, pictorella finch, Bengalese finch, border fancy canary, grey DESCRIPTION OF THE ORGANISM
Megabacteria originally was thought to be a Megabacteria has also been seen in the Japanese bacteria -- a very large one, as the name implies. It quail, European goldfinch, and ostriches. In is an enormous gram-positive, periodic acid-Schiff budgerigars, some think it seems to affect “English” exhibition budgies more than the American (or pet) antibiotics that have been tested against it proved strain of the same breed. I have checked with useless while fungal medications seem to be more veterinarians as well as human epidemiologists, and effective, which makes many suspect that its true they do not believe at this time that it is transferable nature is fungal. Some researchers found typical bacterial structure via transmissionelectronmicroscopy; others saw none. For SYMPTOMS
example, some found a distinct eukaryotic nucleus, Megabacteria first becomes apparent when birds in which bacteria do not have. Yet others claim that good condition suddenly become fluffed up, lethargic, and severely depressed. Early on, slimy width, the absence of intracellular membrane-bound seeds are regurgitated leaving a visible smear on the organelles, and the presence of nucleoid-like areas.
bird’s mask. On occasion the birds may vomit Still another ultrastructural study showed that there blood. Many appear to eat frantically, but no food was an extensive intracellular membrane network, is actually consumed. They grind the seed or pellets but the organelles had not been shown to contain into dust, but don’t actually consume any food.
DNA -- which makes it non-fungal in nature. More Palpation will show the crop to be empty. Some research is needed to discover the true nature of this birds stretch their necks up in the air or mouth-gag pathogen and to decide whether or not it may be repeatedly, appearing to have trouble either deserving of its own classification.
swallowing or regurgitating. The droppings aredark green to brown/black, sometimes reddish- tinged, with very little white color (urates), and Megabacteria is thought to have been introduced sometimes tarry while being small in size. Despite into Australia with imported English budgies in the kinds of food offered, affected birds invariably 1989-90, causing great losses in the early 1990s but lose body weight with the breast muscles wasting have declined markedly in the last few years. It is away and the keel becoming prominent on the chest.
unknown whether this is due to some natural Canaries may develop swelling of the abdomen as immunity or to better knowledge and control. It has the intestines are invaded by the organism. In the been detected in some wild populations of last stages of the disease, no subcutaneous fat can MEGABACTERIA - A REVIEW OF THE LITERATURE By Claire Talltree, MSW Page 2
be found and the muscles have atrophied andwasted away.
In any event, there should be no harm incommencing treatment for Megabacteria until In the acute form, birds usually die within a few days. In the chronic form, the birds becomeprogressively more emaciated and debilitated over a TREATMENT: TYPES OF DRUGS
number of weeks or months and then either die, or As previously mentioned, researchers have tried appear to recover but then relapse weeks or months several antibiotics against Megabacteria to no avail.
Of all the microbicides and antiseptics tried, onlyChlorhexidine Gluconate (Nolvasan) in the drinking DIAGNOSIS
water seemed to help. One vet recommended 20 cc.
Megabacteria primarily lives in the proventriculus, Chlorhexidine Gluconate mixed into a gallon of the glandular stomach before the gizzard. There are water with 8 teaspoons of sugar to improve the three basic ways for a vet to diagnose it. In some taste, and providing it in the drinkers for 3 weeks.
cases Megabacteria can be found in a crop wash.
Unfortunately, the literature suggests that The second, and easiest, way to diagnose it is through a fecal test. To perform this test, take a fresh fecal sample, do a thin uniform wet mount on question about the long-range toxic effects of a slide, perform a gram-stain test, cover it with a 22 Chlorhexidine taken internally over a long period of x 22 mm coverslip, and scan at 100 x magnification.
The Megabacteria should look like large blue rods.
Viewed at 1000 x magnification, the megabacteria One researcher suggested that, since birds that are can be more easily seen. Be warned that a fecal test having trouble with Megabacteria have raised pH is indicative only about 80% of the time; some levels, acidifying the upper GI tract might help to birds have it but tests doesn’t show it. The third, control outbreaks. This, however, would not cure and most accurate, way to diagnose Megabacteria is the disease but only help treat the symptoms.
to present the bird for necropsy to an avian Several fungicides have been tried: nystatin B veterinarian. Megabacteria is found by examining a (Nilstat), ketoconazole (Nizoral), and amphotericin scraping of the gut lining; the proventriculus will B (Fungilin). These all have worked against be distended, containing a large colony of these Megabacteria, however it soon built up a resistance organisms lined up along the wall of the stomach.
to the first two. Amphotericin B is the only drug so Unfortunately, diagnosing this way means either far that has proven effective against the disease.
waiting until the bird dies or is sacrificed, but inmany cases it is the o TREATMENT: ADMINISTRATION
METHODS
Several methods of administration have been tried:
DISEASE OR DISEASE PROCESS?
intramuscular injection, intravenous injection, crop It is thought that the mere presence of Megabacteria injection (gavage), crop feeding tube, and addition in a bird won’t tell you much. Research has found to the drinking water. Neither intramuscular or twenty-seven to sixty-four percent of all budgerigars intravenous injection worked in any drugs tests; in are carriers but exhibit no symptoms. Because of fact, one researcher mentioned severe tissue damage this, it is unknown if Megabacteria is simply part of from both methods. Most of the water methods the common gut flora of birds that opportunistically proved useless as the birds didn’t like the taste of waits for some other disease or problem to occur for the medication and refused to drink. As it was oil- it to strike, or if it is pathogenic (a causative agent based, it also didn’t mix well with water. The only in disease) and should be classified as a disease method that proved effective was twice-daily crop itself. It is unclear at this time whether it is its own disease or part of a larger disease process.
Obviously, this method of introducing amphotericin Because of these uncertainties, there has been some B is not practical in an aviary setting. It is quite vagueness in naming the disease. Some call it stressful to the bird to be caught, physically “going light”, budgie wasting disease, bacteria restrained, injected into the crop, and then released.
giganticus, Megabacteria Associated Disease It is also very time-consuming for the owner to do (MAD), or Proventricular/Ventricular Disease this for every bird twice a day. Researchers began (PVD). It may even play a part in Proventricular to re-think water-based treatment, for lessening the Dilation Disease (PDD), which has found to be viral stress on the birds and ease of administration.
in nature by Dr. Branson Richie of Georgia However, as budgies have been known to survive MEGABACTERIA - A REVIEW OF THE LITERATURE By Claire Talltree, MSW Page 3
happily up to 45 days on dry seed without any generations of Megabacteria in the laboratory.
water, a method had to be found to improve thetaste. There was also the problem that amphotericin NEXT STEPS
I see several things that need to be done in regardsto Megabacteria. These are: Vetafarm in Australia was the first to develop awater-based formulation of amphotericin B. They • Educate the public about the disease.
named it Megabac-S. Due to their manufacturing • Educate veterinarians about the disease, technology, it is not only water soluble but also including diagnosis and treatment. particularly potentiated, and subsequently there is far more • Develop c onsistent diagnostic procedures, manufacturing process incorporates the molecule in including steps to rule out other diseases. It is a sugar ring. This has a two-fold action of creating important to also evaluate the efficacy of solubility in an otherwise insoluble chemical and protecting the chemical. When the sugar ring is denatured in the gut, the chemical is released. This formulation is safe up to a tenfold increase in Megabacteria, to aid efforts in developing better concentration. The suggested dosage, which is 1 treatments and in the creation of a vaccine.
gram per 200 milliliters of drinking water, is • Promote the use of sound quarantine systems, stress reduction (which may be an importantfactor in its development), and preventative Using this formulation, known infected trial birds under controlled conditions have shown complete • Develop better access to drugs through eradication of the Megabacteria when retested three licensing. Megabac S is not licensed as a drug months later. However, there is always an in the United States, but may be purchased and exception, and there have been a few sporadic legally imported as a “nutritional supplement”.
failures when field testing the drug. Why these The FDA allows bird breeders to legally import failures occur is not known at this time, but it is it into the United States for their own use and guessed that the organism escaped the gut and not for resale. Other countries may be denied became systemic. One researcher found a bird that had Megabacteria in its liver! Sometimes, too, thebird may have been treated too late in the disease I am also in the process of creating a Web page process to recover from damage caused to the about Megabacteria that will include ongoing proventriculus, and although it no longer has discussion, new research, and articles. I hope that, Megabacteria in its system it may never fully by bringing all the information together in one place, this will facilitate taking the next necessary PREVENTION OF TRANSMISSION
steps in stopping this disease. I welcome any ideas It is believed that Megabacteria is spread fecally, or information, and can be contacted by email at although there have been no studies at this time on [email protected] or by telephone in the USA at possible methods of transmission. It makes sense, though, that since Megabacteria appears in the fecesthat it would be prudent to maintain good WEB SITES, RESOURCES, AND ARTICLES
housecleaning, i.e.: daily removal of all droppings.
Anderson N. Candida/megabacteria proventriculitis It is also thought that transmission may occur in a lesser sulphur crested cockatoo (Cactua through communal use of waterers; again, this can sulphurea sulphurea). Journal of the Association of be prevented by good and regular housecleaning. It is also suspected that the normal habits of the birds feeding each other, as in courtship, might be a budgerigars. Veterinary Record 1992;131:12-14.
Beck P. My experience with megabacteria. The Studies have attempted to transmit the disease from known carriers to other birds. In one instance, two Bradhauer MG. Megabacteria and proventricular/ pairs of adult birds whose fecal tests were negative ventricular disease in Australian birds. Australian were housed with two pairs of known positive birds Association of Avian Veterinarians Annual for 14 months and the Megabacteria negative birds Conference, 1996 Main Conference Proceedings.
remained consistently negative. There has also Brewster M. Tacoma, Washington. He has done been little success with culturing successive MEGABACTERIA - A REVIEW OF THE LITERATURE By Claire Talltree, MSW Page 4
associated with “going light”. Veterinary Record Davis RW, Kenzy S, Stauber EH. A preliminary Huchzermeyer FW. Gastric stasis in ostriches.
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Ostrich Discussion Group Extraordinary Meeting, Dorrestein GM, Zwart P, Buitelaar MN. Problems Huchzermeyer FW, Henton MM, Keffen RH. High arising from disease during the periods of breeding mortality associated with megabacteriosis of and rearing canaries and other aviary birds.
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Polyoma which can be found at: www.mecca.org/ Filippich LJ, Parker MG. Megabacteria and proventricular/ventricular disease in psittacines and Scanlan CM, Graham DL. Characterization of a passerines. Association of Avian Veterinarians gram-positive bacterium from the proventriculus of Annual Conference;1994 in Reno Nevada USA.
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Hargreaves RC. A fungus commonly found in theproventriculus of small pet birds. Proceedings 30thWest Poultry Disease Conference and 15th PoultryHealth Symposium, University of California-Davis Note: no portion of this article shall be reproduced without the prior consent of the author.
Henderson GM, Gulland FMD, Hawkey CM.
Hematological findings in budgerigars withmegabacterium and trichomonas infections MEGABACTERIA - A REVIEW OF THE LITERATURE By Claire Talltree, MSW Page 5
Fæcal and Proventriculus gram-stains x1000 Photographs courtesy of Vetafarm Research Facility by

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