The survey, taken during the Edinburgh International Science Festival, indicated 87 percent of the 200 individuals questioned did not know the disease has been wiped out.

The poll conducted by Scotinform for the Society for General Microbiology did find many know quite a bit about microorganisms.

Three-quarters know microbes are used to make medicines, more than half know bacteria can live inside active volcanoes and 44 percent know microbes ferment cocoa beans used to make chocolate.

Dr. Bernard Dixon reported the results at the SGM's annual meeting held in Edinburgh.

"Overall, these results are reassuring," Dixon says in a statement. "However, there are a few worries. For example, while 80 percent of people knew that microbes were invisible forms of life such as bacteria and viruses, this did not apply at the lowest age range. Nearly 40 percent of those age 16 to 24 did not know what microbes are."

Ignorance concerning smallpox is disquieting since the disease killed 300 to 500 million people during the 20th century before a World Health Organization vaccination campaign made it extinct in l979, Dixon said.