After four years, the eradication effort, directed out of a $1.2 million American-built base in the Huallaga Valley, has only blunted the explosive spread of the coca crop.

Some medical experts believe the chances of an explosive spread of the disease to Europe, including Britain, cannot be discounted.

The report does not contradict assertions by American health officials that there will be no "explosive" spread of the virus in the heterosexual community.

The explosive spread of computers has also accelerated demand for efficient links that can easily ship large volumes of data across national boundaries.

It reminds us that such transportations are a cause of the explosive spread of infectious animal diseases.

But by next year, according to some industry estimates, Internet usage in Japan will be the highest in the world, largely as a result of the explosive spread of cellular phones.

"That rampant, explosive spread," he said, "and the dramatic way it's killing poultry so rapidly suggests that we've got a very beastly virus in our midst."

Dr. Jaffe said, "Those who are suggesting that we are going to see an explosive spread of the virus into the heterosexual population have to explain why this is not happening."