Published Date: 2010-07-09 15:00:04
Subject: PRO/AH/EDR> Botulism, avian - USA (03): (CA)
Archive Number: 20100709.2294
BOTULISM, AVIAN - USA (03): (CALIFORNIA)
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Tue 6 Jul 2010
Source: AppealDemocrat.com [edited]
Botulism blamed in Ellis Lake duck deaths
The bodies tend to collect in just a few places along the perimeter
of Ellis Lake, some floating upside down, others on their sides. At
least 30 dead ducks have been spotted there in the last couple of
weeks. Several more ducks have been described as seriously ill. An
outbreak of avian botulism is believed responsible.
"I found a flapper yesterday [5 Jul 2010]," said Dale Whitmore, a
state Department of Fish and Game biologist, about a sick bird he
spotted Monday morning.
Avian botulism, "paralyzes their necks. They can't hold their heads
up and they drown," he said. [A great description of why avian
botulism is sometimes called limberneck. - Mod.TG]
Whitmore found and removed about a dozen dead birds the day after a
Fourth of July celebration that featured motor boat and cardboard
On Tuesday [6 Jul 2010], 13 duck bodies bobbed among cans, bottles,
cups, and chip bags, mostly at the north end of the lake, and just
south of 14th Street.
[A 17-year-old], of Marysville, was showing her boyfriend from
Sacramento around the lake shortly after the boat races on Sunday [4
Jul 2010]." He said, 'Oh look - a dead duck,'" [the girl] said. "Then
we saw another and another and another. They were everywhere. I
counted 25 before we left."
Marysville City Services Director Dave Lamon said the lake water had
been treated last week [week of 28 Jun 2010] to try and limit algae
But a lack of fresh water combined with heat and an over-population
of birds have made for a particularly gruesome summer.
According to the US Fish and Wildlife Service, decaying organic
matter is where maggots, which carry the virus without becoming sick
themselves, thrive, and eventually sicken ducks and some other birds
that feed on them.
Overly dense vegetation can reduce oxygen levels and kill aquatic
animal life, thus drawing flies and perpetuating this cycle.
"We've got an inherent problem at Ellis Lake," Lamon said. "They
(waterfowl) come in during the regular migration. People feed them
and so they stay."
The lake is fed primarily by run off from storm drains and is not all
that clean to begin with, Lamon said. Add too many ducks, and they
help to create a health hazard for themselves. "Their poop doesn't
have much place else to go except the lake," he said.
Budget cutbacks in recent years have minimized the amount of clean
water the city pumps in, and the frequency with which it is pumped.
Even in late summer when the city adds the most water, the lake
simply becomes diluted, Lamon said.
It would take roughly 30 days of constant pumping to change the
existing water, he said.
In past years, when too many ducks and geese have shown up, Lamon
said, they have been trapped after or just before the spring and
early summer nesting seasons. Fish and game agents relocate them,
usually to local rivers.
Botulism claims some ducks every few years, he said. But the current
outbreak seems to be especially deadly.
[A 16-year-old], was surprised to see several dead ducks while
exercising his dog on the path around Ellis Lake Tuesday [6 Jul
2010]. [He] said he lives nearby and visits the lake frequently with
his parents. They are accustomed to seeing an occasional dead animal
there. "But, heck yeah, this is more than usual," he said.
According to Whitmore, the disease is simply, "nature's way of
handling overpopulation (of ducks)."
Curbing the further spread of botulism, he said, will require that
dead ducks be removed right away so they don't attract flies, and
create the maggots that other ducks eat.
After seeing so many dead and dying animals on Sunday [4 Jul 2010],
[the girl] said, her boyfriend didn't want to ever see the lake
again. The 2 of them, she said, felt shocked and sad for the ducks.
"Ellis Lake is supposed to be their little sanctuary," she said.
[Byline: Nancy Pasternack]
[The sporulating anaerobic Gram-positive bacillus _Clostridium
botulinum_ elaborates 7 types of antigenically distinct neurotoxins,
4 of which affect humans: type A, B, E, or rarely type F toxin. Types
A and B toxins are highly poisonous proteins resistant to digestion
by GI (gastrointestinal) enzymes. About half of the foodborne
outbreaks in the United States are caused by type A toxin, followed
by types B and E.
Type C botulism occurs principally in waterfowl and other birds
living in an aquatic environment and causes tremendous losses, most
notably in waterfowl in the western US. In addition to North America,
it has been reported in birds in Europe, South Africa, Uruguay, and
Australia. In the Great Lakes region, it was 1st identified in 1936
in ducks on Green Bay of Lake Michigan and in 1941 in Monroe County
marshes along Lake Erie. Type C is most often associated with
limberneck paralysis in birds.
Type E botulism is connected with consumption of fish and occurs
mainly in gulls and loons, and to a lesser extent in mergansers, mute
swans, grebes, and shorebirds. It now appears any birds or mammals
susceptible to botulinum toxin run a risk of becoming poisoned if
they scavenge dead fish. Evidence for this includes the
identification of type E toxin in a bald eagle, wood ducks, and
muskrats with fish remaining in their digestive tracts.
Typically a bird dies of some cause, and the carcass is an incubator
for the anaerobes. The maggots move into the decomposing carcass,
accumulating the toxin. Other birds come to eat the maggots on the
carcass and infect themselves, dying from the very disease they
consumed, and so the circle gets larger and requires that carcasses
to be picked up, or the cycle continues. - Mod.TG]
[The state of California can be located on the HealthMap/ProMED-mail
interactive map of the US at
<http://healthmap.org/r/01G6>. - Sr.Tech.Ed.MJ]