Magazine article Science News

Making Wetlands Safe from Avian Botulism

Magazine article Science News

Making Wetlands Safe from Avian Botulism

Article excerpt

More and more birds are dying of avian botulism, the most serious disease of wetland bird species. Wetland managers have few good strategies for combating the threat, but they may soon have some effective weapons against the toxin that causes the disease, says animal disease specialist Tonie E. Rocke.

Rocke and her colleagues at the National Wildlife Health Research Center in Madison, Wis., have developed new genetic techniques for studying the botulism toxin, and they report new findings on the importance of salinity and pH in the life of the poison.

A problem worldwide, avian botulism kills hundreds of thousands of birds, including zoo animals, every year in the United States alone. A single outbreak in Russia in 1981 killed more than 1 million birds. The botulism toxin acts by disrupting the nervous system and causing paralysis.

During the last 5 years, Rocke and her colleagues have compared 31 wetlands in the United States where botulism outbreaks have occurred and similar locations where they haven't. She reported the results at the American Society of Zoologists meeting last week in Washington, D. C.

The scientists found that the risk of a botulism outbreak peaks when wetlands have a relatively neutral pH-between 7 and 8 for soil and between 7.5 and 8.5 for water. Also, the risk of botulism decreases when wetlands are salty.

A virus carries the gene that codes for the botulism toxin, but the virus must enter an anaerobic bacterium, Clostridium botulinum, in order to produce the toxin. …

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