Published Date: 2011-09-23 17:10:25
Subject: PRO/AH/EDR> Undiagnosed die-off, avian - USA (08): (CA) botulism susp.
Archive Number: 20110923.2878
UNDIAGNOSED DIE-OFF, AVIAN - USA (08): (CALIFORNIA) BOTULISM SUSPECTED
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Mon 19 Sep 2011
Source: The Orange County Register [edited]
Mallards dying in Lake Forest lakes
In the last 2 weeks, more than 30 dead or dying ducks have been found
at ponds and lakes around the city.
Residents of the Lake I and Lake II communities have reported finding
hen and drake mallards floating in the lakes there and flopping on
nearby grass. Dead ducks also have been found at Village Pond Park and
nearby at the Forest Gardens Mobile Home Park. Officials from Orange
County Animal Care have picked up some of the dead birds, and
residents have tried to save some birds by taking them to the Wetlands
& Wildlife Care Center in Huntington Beach.
A Lake I resident is concerned bread being fed to the ducks at Village
Pond Park coupled with the recent heat and algae forming in the water
are contributing to the growth of botulism.
"The city does no enforcement," [she] said of regulations prohibiting
feeding ducks. "I've seen a baker's truck unload at the duck pond and
people out there all day with non-duck food. It's very sad to see them
just dying and flopping around."
[Byline: Erika I Ritchie]
ProMED-mail from HealthMap alerts
[The photo in the original article at the source URL above shows a
duck with a limp bent over neck. This is some times called
"limberneck" and is another name for botulism. The conditions
mentioned above may have contributed to this situation but it is
impossible to comment on where the botulism came from with only the
information in this article. However, if the dead bodies are not
removed from the site, they continue to be part of the cycle. As
maggots form in the carcasses they are filled with botulism. Those
maggots are great bird food, as well as a source of more botulism.
Avian botulism is a paralytic disease caused by ingestion of a toxin
produced by the bacteria _Clostridium botulinum_. These bacteria are
widespread in soil and require warm temperatures, a protein source,
and an anaerobic (no oxygen) environment in order to become active and
produce toxin. Decomposing vegetation and invertebrates combined with
warm temperatures can provide ideal conditions for the botulism
bacteria to activate and produce toxin. There are several types of
toxin produced by strains of these bacteria; birds are most commonly
affected by type C and to a lesser extent type E.
Birds either ingest the toxin directly or may eat invertebrates (such
as chironomids [non-biting midges], fly larvae) containing the toxin.
Invertebrates are not affected by the toxin and store it in their
body. A cycle develops in a botulism outbreak when fly larvae
(maggots), feed on animal carcasses and ingest toxin. Ducks that
consume toxin-laden maggots can develop botulism after eating as few
as 3 or 4 maggots.
Healthy birds, affected birds, and dead birds in various stages of
decay are commonly found in the same area. The toxin affects the
nervous system by preventing impulse transmission to muscles. Birds
are unable to use their wings and legs normally or control the 3rd
eyelid, neck muscles, and other muscles. Birds with paralyzed neck
muscles cannot hold their heads up and often drown (the disease has
occasionally been called "limberneck"). Death can also result from
water deprivation, electrolyte imbalance, respiratory failure, or
Portions of this comment have been extracted from
[A HealthMap/ProMED-mail interactive map of California can be seen at
http://healthmap.org/r/1h2c. - Sr.Tech.Ed.MJ]