Topics on this Page:
Introduction
It goes by various names - among them "finch eye," the "eye disease," "House
Finch Conjunctivitis," and the medical name, Mycoplasma gallisepticum
- or simply "MG." From the earliest reported sightings I
am aware of, it began showing up at bird feeders in January, 1994, in the
dead of an icy winter in the Maryland suburbs northwest of Washington, D.C.
House finches suddenly began appearing with one or both eyes badly swollen,
nearly blind, struggling to find the feeders they had come to depend on,
perhaps for much of their lives. Within a matter of weeks and months the
disease had spread to much of the mid-Atlantic region and by year's end had
reached most of the eastern seaboard of the US and parts of Canada. The sight
of swollen-eyed finches has become so widespread across parts of the eastern
half of the US and southeastern Canada that, by now, for many people it may
be the most common wildlife disease they will come across.
Yet during these past three years, finding information about this disease
- for both bird feeding enthusiasts and wildlife rehabilitators alike - has
been difficult. Aside from those who took the initiative in contacting wildlife
authorities directly, for most people information about the MG outbreak has
been largely confined to sporadic newspaper articles, internet message boards
and list service postings, and word of mouth. Finally, a number of web sites
have begun to provide some specific MG-related information. For example,
a treatment protocol for MG was posted last year on a wildlife rehabilitators
web site. The Cornell Laboratory of Ornithology also went online with a web
page for its House Finch Study, aimed at potential Project Feeder Watch
participants who wish to help track the spread of MG. And more recently an
important article appeared in the online version of the Centers for Disease
Control journal, Emerging Infectious Diseases. What was
needed, however, was a way of tying all of these resources together, along
with other related ones, while at the same time providing additional help
for those confronting MG, in terms of recognizing and coping with it. That
is the goal I hope to achieve here.
- Jim Cook, Germantown, MD
Send comments, questions to me at
FinchMG@aol.com
There is a great deal of information on the world wide web on this subject,
owing primarily to Mycoplasma gallisepticum's prevalence in poultry.
According to
one
source (1), "Mycoplasmas are a diverse group
of ... bacterial pathogens considered ... to be the smallest free living
organisms known." They are very primitive and differ from common microorganisms
in that, rather than having cell walls, instead they have an outer jelly-like
or plasma membrane exterior. Mycoplasma gallisepticum is a specific
Mycoplasmal organism known to produce disease in avian hosts. Until 1994
it had only been found in poultry, primarily chickens, where it is a major
concern, as well as in domestic and wild turkeys and other upland game birds.
Yet Another web
site (2) notes that according to Dr. Syed A. Bokhari of the University
of California, one-third of all table egg-laying flocks in the US have MG
and that perhaps 90% of backyard poultry flocks are infected with it as well.
Since it had not been seen in songbirds prior to 1994, this new strain affecting
house finches is considered a new disease. Recent DNA investigations have
been unable to identify the finch strain of MG with any poultry strain or
vaccine tested thus far (see For Further Information,
below; hereinafter this study will be referred to as the "Ley EID DNA
Study").
- (1)
http://microbes.micro.iastate.edu/~FCMINION/FCMINFO.html
-
(2) http://www.avian.umn.edu/SFPC/Mycoplasma.html
[Note: Throughout these pages, in cases where a hyperlink to an Internet
web site is not followed by its URL, their URL address may be found on the
page "Web Links and Other Resources."]
It had been originally speculated that the MG organism at some specific,
yet unidentified poultry farm, possibly in Maryland or Virginia, had become
receptive to songbirds and, during the winter of 1993-94, "jumped species"
to house finches when finches in these states might have resorted to feeding
at this contaminated poultry farm during harsh winter weather. During that
time frame, the Washington, D.C. area, where the first reports of swollen-eyed
house finches arose, was subject to a number of ice storms, possibly leaving
normal food sources covered with ice and inaccessible for prolonged periods.
However, since the previously -referenced Ley EID DNA Study was not able
to match the DNA of the finch strain of MG to any of the poultry strains
or MG vaccines it tested, nor has any other lab tied it to any other strains
of MG (to my knowledge), the original source of the house finch strain remains
a mystery (although small, unregulated poultry flocks are still suspected
as a possible source). Others theorize MG may be more common in wild
birds then previously thought, but that it had perhaps gone undetected until
1994.
One of the more striking aspects of the outbreak was the suddenness with
which it spread, appearing in many areas across the mid-Atlantic region within
a few short weeks and months. As noted in another important study appearing
in a previous issue of the CDC journal Emerging Infectious Diseases,
hereinafter referred to as the "Fischer EID
Article" throughout these web pages [See "For
Further Information, below], eastern house
finches can migrate many hundreds of miles in any direction, perhaps accounting
for the diseases' rapid spread. Additionally, some have further expressed
the possibility that MG may lurk in finches in a dormant state, only to be
activated by great stress of some sort (which is true of MG in poultry).
For example, both outbreaks of MG first involving house finches and later
in goldfinches, occurred in the dead of winter, following severe winter episodes.
The three times I have observed swollen-eyed goldfinches occurred within
days of major winter storms. While this is entirely speculation on my part,
perhaps MG's near-simultaneous appearance in house finches in the Maryland
suburbs of Washington, D.C., central Virginia, Delaware and other northern
sites within a short time could indicate that finches carrying the organism
had dispersed over a wide area before the onset of severe winter that activated
this disease condition.
After three years, although it has been occasionally seen in American goldfinches
(see "Can Other Birds Get MG?," below)
and there remains great concern over its possible spread to other songbird
species, MG remains essentially a disease of house finches. House finches
may have been particularly susceptible to MG (and perhaps other diseases)
for a number of reasons. Some suspect that, at least in so far as the eastern
house finch population goes, they may have a weakened immune system as a
matter of heredity or inbreeding. The eastern population was introduced over
fifty years ago when hand reared western house finches were released by pets
stores in response to a change in wildlife legislation that restricted use
of wild birds in the pet trade. All the house finches in the eastern half
of the United States are assumed to be descendants of this introduction in
the 1940's. Some people feel that inbreeding and a small, genetic pool could
leave subsequent generations of eastern house finches more susceptible to
disease. This theory, however, does not explain the presence of MG in goldfinches
during 1996 and 1997.
In any case, the very nature of house finches themselves has no doubt
helped make them more susceptible to disease spread in general - MG and
otherwise. House finches simply love the company of other house finches.
And they had become, according to an edition some years ago in the comic
strip Mark Trail, the most common species frequenting bird feeders
in North America. Both of these factors would encourage the rapid spread
of a new disease, like MG. (See section
"How is MG Spread?")
The April, 1997, issue of the
Southeastern Cooperative Wildlife
Disease Study Briefs has an article about MG in finches and chickens,
which indicates that MG is now confirmed in 33 states. (A text copy of this
document can be found on "Web Links and Other
Resources" page.) These states range from the East Coast to the Mississippi
River Valley. Testing done on finches with symptoms of MG found in Waco,
Texas, in April, 1997 were recently confirmed to have had MG, thus confirming
disease's arrival in that area. I have also personally heard of unconfirmed
reports in Kansas, Nebraska, Oklahoma and other areas within the state of
Texas.
The Fischer EID Article contains a map showing the spread of MG through June,
1996, prepared by the Cornell Laboratory of Ornithology, based on data from
its House Finch Study being conducted in connection with their Project Feeder
Watch. Additionally, the National Biological Service's Breeding Bird Survey
NBS House Finch Species
Account provides a current range map (based on average counts during
the period of from 1982 through 1996) for house finches and their relative
abundances across North America. I have prepared a composite graphic, below,
showing these two maps side-by-side [Figure 1]. {Note - please keep
in mind this data is now 12 months old.}
It can be seen from the range map provided here, and comparing it to the
Cornell Lab's map of MG's spread, why it irrupted so rapidly from the
mid-Atlantic region in 1994, moving into Pennsylvania, New Jersey, New York
and New England: the Washington, DC, area, where first reports arose, is
at southern edge of the densest area of the house finches'range in the East.
These areas also overlap major eastern urban and suburban centers where bird
feeding is especially likely to occur. Comparing the two maps also shows
that by June, 1996, MG had spread throughout almost the entire
eastern house finch population's range. But where the NBS range
map shows the western and eastern populations having merged (the general
area of Nebraska and Kansas), there is a bottle neck which MG presumably
would have to pass through to infect the original western population. This
area, as well as other areas shown in light pink, shows house finch relative
abundances as very low. On the one hand, these areas might seem to act as
a buffer, slowing down the MG's westward spread. (Additionally, the fact
that urban and suburban areas, as in effect, centers for bird feeding, are
themselves more dispersed in western areas might also help contain the spread
of MG throughout the western US.) However, with the recent confirmation of
MG's arrival in Waco, Texas, then it has already indeed breached the lowest
density areas of the house finch range, with the much more dense areas of
from western Texas to the California coast lying not very far away.
If the NBS BBS house finch relative abundance map reasonably reflects true
house finch densities, MG may be poised to irrupt into the Southwestern US
and the Pacific Coast in the not too far distant future, perhaps even more
severely than it did in the mid-Atlantic area in 1994, considering that relative
house finch abundances are even greater in many of these western areas than
in the mid-Atlantic areas where it began. On the other hand, if the eastern
population does indeed have a weakened immune system, as some suspect, we
may soon know if this is true depending on how severely and quickly the disease
affects the western group.
The most obvious symptom produced by MG in finches is conjunctivitis - producing
watering, crusting, and swelling of the eyelids and conjunctive tissues
surrounding the eyes (see "Recognizing MG" for
photos). I am not aware of any published scientific studies which confirm
or deny if MG can kill or blind finches or if finches survive long enough
to recover from it on their own. The Summer, 1996, issue of the Cornell
Laboratory of Ornithology's newsletter, Birdscope, carried a
report about a bird bander who, in November, 1994, had released 126 banded
finches with symptoms of conjunctivitis (out of a total 779). 45 of these
were subsequently recaptured later, of which 6 no longer showed signs of
the disease, apparently having recovered on their own. She also found one
finch that still had symptoms three months after being released, indicating
some finches could survive with the disease for some time. However it would
seem the majority of finches, especially if both eyes are affected, probably
die quickly. MG causes the eyes to water greatly, and/or become glued shut
by the drying of these eye secretions, or by causing the eyelids to become
so inflamed that the swelling itself closes the eyes. Rubbing of eyes can
further damage eye tissues by scratching the cornea directly or
by resulting in secondary infections which themselves can damage vision
permanently, in some cases. Many infected finches will die of starvation
because they are unable to forage for food and water, or fall victim to predation
from hawks or, more probably, cats.
Until recently, for the most part, the only "proof " I had that MG is taking
a toll on house finch numbers came from anecdotal reports of the drops in
the numbers of house finches observed at bird feeders I have gotten from
people around the eastern US. Some of these reports are more empirical than
others and may well be a truer indication of MG's impact on house finch numbers
overall. One such report from Canada was part of an ongoing, formal census
of house finch populations over the past dozen or so years. It noted that
house finch numbers were down 40 percent since the arrival of the disease
there, and perhaps down another 30 percent in their more recent surveys.
However, an Associated Press wire service story, dated
September, 18, 1997, entitled "Cornell study lists top visitors to America's
bird feeders," also reports that Cornell University's Project FeederWatch
has "found that the number of house finches appearing at home feeders continued
an alarming decline," noting further that "what is disturbing to ornithologists
is that fewer finches were seen at each sighting and their visits were less
frequent, said Diane Tessaglia, the project's coordinator." "While
they've been appearing at more feeders across the continent, their numbers
in the East have been declining recently, she said. This year, the average
flock size dropped by nearly a quarter, to less than five a sighting." [Paragraph added Nov.2, 1997] [See "What to
Do" for information about and links to the Cornell Laboratory or
Ornithology's Project FeederWatch and House Finch Study.]
Hopefully, the National Biological Service's Breeding Bird Survey, the
Audubon Christmas bird counts and the Cornell House Finch Study and Project
Feeder Watch will shed more light on this question as more recent data becomes
available.
On a more hopeful note, none of the researchers studying this disease
I have spoken to or whose studies I have read feel it threatens house
finches as a species in the long run. As explained to me by one wildlife
official, in cases of disease outbreaks such as MG, over time the host species
and the organism typically come into some balance. Either those birds more
resistant to the organism survive and go one to replenish the species, passing
on their immunities to subsequent generations - and/or the disease itself
adapts to the host as its more lethal organisms quickly die off themselves,
having killed their hosts so quickly. Thus the less lethal organisms would
be the ones to survive and spread, with the disease itself becoming less
lethal over time, perhaps eventually becoming a non-lethal parasite. Whether
this is in fact the case in MG and finches remains unknown. If in fact house
finches are recovering from and adapting to MG, hopefully data on this will
soon become available from sources like those mentioned previously.
Yes. However thus far the only other songbird species in the wild beyond
house finches that has been confirmed to have contracted MG are American
goldfinches.
The first songbird beyond house finches known positively to have contracted
MG was a blue jay held in captivity in 1994. It was one of a pair of juveniles
that were being treated in a wildlife center where house finches with MG
had also been kept; both jays came down with symptoms of MG, but a positive
result was only confirmed for this one.
Also in 1994 there had also been reports that the disease had been confirmed
in European starlings in Connecticut. I had heard nothing more on this until,
in doing research for this web page, I found a write up posted on the
internet by the University of
Connecticut (URL @ http://www.lib.uconn.edu/pathobiology/annual95.htm).
It seems the Northeastern Research Center for Wildlife Disease there had
found yet another form of Mycoplasmal infection, this one in starlings, one
it called Mycoplasma sturni, which also produced symptoms of
conjunctivitis. However it noted in its report that, at the same time, it
had been receiving other birds with conjunctivitis symptoms, including house
finches, goldfinches, purple finches, and blue jays, though apparently none
had been confirmed to have had MG.
Relatedly, there have been a number of unconfirmed reports of conjunctivitis
in purple finches. It is possible the reports refer to house finches
misidentified as house finches. However it remains that MG has not been confirmed
in purple finches.
In January, 1995, and again in both January and February, 1996, I personally
observed swollen-eyed goldfinches at my feeders. I managed to capture one
in February, 1996, which subsequently tested positive for MG by the Southeastern
Cooperative Wildlife Disease Study. In addition to mine, the SCWDS had received
a few other swollen-eyed goldfinches from other southeastern states at about
the same general time. Some of these were also confirmed to have had MG.
Apparently shortly just before this, North Carolina State University
had itself already confirmed MG in at least one other goldfinch. (See "Recognizing
MG" section for
photos of Goldfinches with MG.)
A few months later there were reports that a wild Downy woodpecker had been
confirmed with MG in Michigan. However, as I recall, its confirmation was
later retracted (this Downy may indeed still have had MG, but a problem rested
with the tests themselves, if memory is correct). Since then I have heard
of no additional species of songbirds having been confirmed to have contracted
MG. The form used in the Cornell Labs' House Finch Study asks observers to
record instances of conjunctivitis symptoms in a number of common feeder
bird species. If in fact observers have been seeing other species with swollen,
crusted eyes, such as purple finches or other Downy woodpeckers, perhaps
we will be hearing more on this subject from the Cornell Lab in the near
future.
It is interesting to note that during this time a number of wildlife disease
centers, in trying to learn how MG is spread and whether other songbirds
could contract it, had inoculated other songbirds with MG from house finches
in an attempt to induce MG in these other species. To the best of my knowledge,
each failed to produce symptoms. Yet somehow captive blue jays in a lab managed
to come down with it with no apparent direct contact with house finches,
and goldfinches in the wild have also come down with it as well. The fact
that labs were unable to induce MG in controlled settings while both at least
one blue jay and wild goldfinches have contracted it in inadvertent
or non-controlled natural settings demonstrates just how difficult it has
been to study MG's transmission in songbirds. Nevertheless, the SCWDS considered
the disease to be so contagious that it has urged wildlife laboratories and
rehabilitation centers to strictly quarantine finches with MG to keep it
from spreading to other species (see page "Treatment
Issues for Rehabilitators" for more on this).
For more on the DNA studies of the confirmed cases
of MG in these three species (house finches, goldfinches and the one blue
jay) see the Ley EID DNA Study. [See For Further
Information, below.]
[Note, while MG has not been confirmed or even officially suspected in cavity
nesting birds, since house finches do on occasion uses artificial nest houses
(bluebird boxes or purple martin houses, primarily), there is some risk
associated with their nesting in such places. See section entitled
"Nest Box and Purple Martin House Precautions" on the page
"What to Do" for a discussion of this subject.]
As noted previously, MG is already a major problem for the poultry industry.
The question has been, can this new finch strain, which may still one
day be found to have originated with poultry, turn around yet again and reinfect
poultry flocks via finches? In December of 1996, for example, the Michigan
Department of Agriculture issued a New Release on this very issue, suggesting finch -borne MG could indeed threaten commercial
chicken and turkey industries. It further warned that bird feeding
was contributing to the spread of the disease and urged bird feeders to take
steps to help reduce the spread of the disease via feeders, thus reducing
the risk to poultry interests. (A text copy of this news release can be found
on the "Web Links and Other Resources" page.)
More recently, the SCWDS issued the results of a study it had done on the
extent to which the finch strain of MG could infect poultry and in turn whether
poultry infected with the finch strain could be retransmitted to house finches.
They reported that these could in fact occur, however in both cases infection
required direct contact and periods of exposure of at least 8 weeks in the
case of poultry infecting finches and 10 weeks for finches to infect poultry.
There was no finding that transmission could occur indirectly, over wire
or across the room. (See
SCWDS
Briefs, April 1997 at the SCWDS web site, or see text copy of
article here listed on "Web Links and Other
Resources" page.)
Avian disease specialists and wildlife officials are in agreement that the
finch strain of MG cannot infect people and pets, such as cats and dogs.
However, pet birds may be an entirely different matter. If you have pet birds
and you have MG in the finches visiting your feeders, you may wish to keep
your pet birds as far away from your feeders as possible, as a precaution,
at least until more is known about how the finch strain of MG is spread.
This includes keeping windows near feeders closed and making sure that when
you clean your feeders, you do so far away from your pet birds, perhaps even
washing your feeders out doors. While I am aware of no cases of pet birds
contracting the finch strain of MG, and while there may be medications available
for treating it, if needed, it is best to play it safe. Consult your avian
veterinarian for further advice, based on your specific circumstances.
For more authoritative information on the MG outbreak in finches, see the
article entitled,
Mycoplasmal
Conjunctivitis in Wild Songbirds: The Spread of a New Contagious Disease
in a Mobile Host Population, by Drs. JR Fischer, DE Stallknecht,
MP Luttrell, AA Dhondt, and KA Converse, appearing in the online version
of the Centers for Disease Control journal, Emerging Infectious
Diseases, Volume 3, Number 1, January-March 1997. A "Text-Only"
version of this article is also provided here on the
"Web Links and Other Resources" page. For the sake
of brevity, I will refer to this study as the "Fischer EID Article"
in the pages on this web site.)
Additionally, in the July - September, 1997 issue of Emerging Infectious
Diseases, Volume 3, Number 3, can be found the DNA study referenced
above, entitled,
Molecular Epidemiologic
Investigations of Mycoplasma gallisepticum Conjunctivitis in Songbirds by
Random Amplified Polymorphic DNA Analyses, by Drs. DH Ley, JE Berkhoff,
and S Levisohn. A "Text-only" version of this article is also provided
here on the "Web Links and Other Resources" page.
For the sake of brevity, I will refer to this study as the "Ley
EID DNA Study."
© 1997 James Cook
All Rights Reserved
