From mgs23@pacbell.net Wed Aug 11 16:35:53 1999 Date: Wed, 11 Aug 1999 12:07:51 -0700 From: Misha To: SANET-mg Subject: Limberneck/avian botulism Howdy, all-- Loren Muldowney's story about "limberneck" resulting from feeding chickens on maggots is one I'd heard from a local knowledge perspective out east, as well. My dad worked on some friends' pig farms in Essington, PA, before and after his service in World War Two. Most of those farms were diversified and also had poultry, and I can remember him talking about this. He was a compassionate man, and couldn't stand to see animals suffering. Loren--good question you raised--because you've challenged my thinking that these maggots could be biocontrolled by birds in an urban composter. See below. "Limberneck" is a condition caused by avian botulism. I posted here recently about ponds as reservoirs of avian botulism. --U.S. Fish and Wildlife service info: http://www.emtc.nbs.gov/http_data/nwhc/factshts/avian.html The authors are at the National Wildlife Health Laboratory, in Madison. "Avian Botulism affects the nervous system, causing muscle paralysis. Depending on how far the disease has progressed, various levels of paralysis will be observed. An early sign in birds is the inability to fly. Once the ability to fly is lost and leg muscles become paralyzed, ducks suffering from botulism often propel themselves across the water and mud flats with their wings. This sequence of signs is in contrast to that of lead-poisoned birds, which have difficulty flying but remain able to walk and run. "Paralysis of the inner eyelid and neck muscles follows. These are the two most easily recognizable signs associated with avian botulism. The inability of the bird to hold its head erect is the reason this disease is called "limberneck." Frequently, birds will drown once they reach this stage in the disease. Those that do not drown will eventually die from respiratory failure as paralysis spreads. "Favorable environmental conditions occur in the tissues of decaying animal and insect carcasses. The decomposition process uses up all available oxygen in the carcass, creating anaerobic conditions. Bacterial spores ingested during the life of the animal germinate after death. As the bacteria multiply and die, the toxin is released. "The cycle of avian botulism "Outbreaks of avian botulism occur when the toxin is taken in by birds. The die-off may begin as birds feed directly on invertebrate carcasses that contain the toxin, or as a result of feeding on live maggots of flesh-flies and blowflies. Flies lay their eggs on dead vertebrates, and the resulting maggots store botulinal toxin in their bodies as they consume the carcass. More than 5,000 maggots can be produced by a single bird carcass; consumption of just two to five toxin-bearing maggots is often enough to kill a duck!" Note that the difference between this and Kate's situation is that the source of the botulinal toxin is dead vertebrates and invertebrates. Kate is decomposing/composting vegetables. Which is what I was thinking when I suggested laying the heap open to the air for city birds to pick at. However, from --Texas A&M http://gallus.tamu.edu/Diseases/PDSec5.htm#BOTULISM comes this: "Botulism is a disease caused by the ingestion of a toxin produced by the anerobic bacterium Clostridium botulinum. All domestic fowl and most wild birds are susceptible. An interesting exception is the vulture, which is apparently immune and feeds on decaying carcasses. Many human deaths have been attributed to their consuming food or water containing the toxin. "Cause: Botulism is not a bacterial infection, but a condition produced by ingestion of a toxin produced by the bacterium Cl. botulinum. The organism is common in nature and is widely dispersed in soils. Ingestion of the organism is not harmful. It becomes dangerous only when conditions are favorable for the growth and multiplication of the bacteria and its subsequent toxin production. The organism grows best under high humidity and relatively high temperature and in an environment containing decaying organic material. Acid conditions are detrimental. Stagnant pools or damp areas containing decaying matter with an alkaline reaction are a danger area. Botulism may result from consumption of any decaying animal or vegetable. Decaying carcasses are a frequent source of toxin, and fly maggots feeding on such tissue may contain enough toxin to cause the disease when ingested. The toxin is water soluble; consequently, water sources may become contaminated. "The toxin is one of the most potent, being about 17 times as deadly as cobra venom for the guinea pig. The toxin is relatively heat stable but may be destroyed by boiling. There are different types of the toxin. Types A and C usually are responsible for the disease in birds, while type B most frequently affects man." So this indicates that maggots in partly-finished compost *could* be a problem for birds, under certain circumstances? There is some good informationon avian botulism/limberneck at: --Environment Canada http://www.mb.ec.gc.ca/ENGLISH/LIFE/MIGBIRDS/AVIANB/ab_1.html See especially, --"Methods of tranfer" for info on maggots: http://www.mb.ec.gc.ca/ENGLISH/LIFE/MIGBIRDS/AVIANB/ab_4.html That site also has an EXTENSIVE annotated bibliography on avian botulism http://www.mb.ec.gc.ca/ENGLISH/LIFE/MIGBIRDS/AVIANB/ab_7.html See especially: http://www.mb.ec.gc.ca/ENGLISH/LIFE/MIGBIRDS/AVIANB/References/ab24.html http://www.mb.ec.gc.ca/ENGLISH/LIFE/MIGBIRDS/AVIANB/References/ab2.html http://www.mb.ec.gc.ca/ENGLISH/LIFE/MIGBIRDS/AVIANB/References/ab175.html http://www.mb.ec.gc.ca/ENGLISH/LIFE/MIGBIRDS/AVIANB/References/ab65.html http://www.mb.ec.gc.ca/ENGLISH/LIFE/MIGBIRDS/AVIANB/References/ab262.html This one intrigued me: it lists a bunch of antibiotics that people can feed chickens to control botulism; this refers back to the ongoing SANET discussion of antibiotics in the food chain, and the notion of drugging animals to overcome pathogens caused by systemic imbalances: http://www.mb.ec.gc.ca/ENGLISH/LIFE/MIGBIRDS/AVIANB/References/ab292.html One last resource: --Skipio's (breeder of insects for kept birds and reptiles) http://www.skipio.com/birds.htm "Insects are a natural nutrition source for all birds at some point in their development except for some who obtain their animal protein from fish, mammals, reptiles or amphibians. Live mealworms and crickets, originally marketed as fish bait, have long been available for feeding birds and other animals. These insects were grown on vegetable diets. Some bird breeders to their dismay tried feeding their birds maggots that were grown on offal or wastes from the local butcher shop. The maggots were suitable for fish bait but could carry claustridium botulinum that resulted in fatal limberneck disease. A mistaken idea associated with those larvae was that they could be cleansed with corn meal. That was not true. Only insects that have been grown on vegetable diets should be fed to birds!" Sooooo. Not sure where that leaves us. My guess would be that if the conditions in the heap weren't too alkaline, and what went into it was clean (not rotted) food, the chance of botulin toxin accumulating in the maggots would be relatively low. Comment, anyone? Hope this is of use to you-all with poultry, as well. I've seen chickens go after maggoty produce, either gleaning in the garden, or something left too long in the scrap bucket (which is also risking Salmonellosis). Finally, Loren, you asked about feeding maggots to fish. Here's a nice little site that looks like a student one, very well referenced: http://iaith.simplenet.com/botulism/botubird.html The student was apparently in a course on Microbial Disease and Human Society. The above URL has an item about botulism in fish, and footnotes. Also: http://www.mb.ec.gc.ca/ENGLISH/LIFE/MIGBIRDS/AVIANB/References/ab50.html Now that we've had this discussion, watch for Dennis Avery to show up claiming that composting causes botulism. :^) (not sure why I'm smiling) peace misha ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Michele Gale-Sinex Communications manager Center for Integrated Ag Systems, UW-Madison http://www.wisc.edu UW voice mail: 608-262-8018 Home office: 415-504-6474 (504-MISH) Home office fax: Same as above, phone first for enabling ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I eat everything. If anything is there, I eat it. I presume it is safe and good. --U.S. Secretary of Agriculture Dan Glickman To Unsubscribe: Email majordomo@ces.ncsu.edu with the command "unsubscribe sanet-mg". If you receive the digest format, use the command "unsubscribe sanet-mg-digest". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest". 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