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
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
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
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
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
firstname.lastname@example.org 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
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Huchzermeyer FW, Henton MM, Keffen RH. High
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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
DIRECTIVA PRESIDENCIAL N° PARA: GOBERNADORES, ALCALDES, COMANDANTE GENERAL DE LAS FUERZAS MILITARES, COMANDANTES DE FUERZA, DIRECTOR GENERAL DE LA POLICÍA NACIONAL, DIRECTOR DEL DEPARTAMENTO ADMINISTRATIVO DE SEGURIDAD ÁLVARO URIBE VÉLEZ PRESIDENTE DE LA REPÚBLICA CARLOS HOLGUÍN SARDI MINISTRO DEL INTERIOR Y DE JUSTICIA ASUNTO: MEDIDAS DE SEGURIDAD DURANTE EL
Driver Improvement Program (DIP) Test 1. The privilege of driving a State vehicle will be suspended if you accumulate more than (?) points on 2. When driving a State vehicle what must be used by the driver and all passengers? A. Operator’s Daily Checklist Form B. Seat belt C. Dramamine D. Reflective vest 3. All State vehicle accidents shall be reported to the Agency’s fleet manag