WILDINGS. “Unique among all forms of artificial life, computer viruses have escaped their playpens and have established themselves pervasively through the the world’s computing environment. Of the world’s 100-200 million PC and Macintosh users n the world…up to half a million have been infected at some time or another.”
https://books.google.com/books?id=8a6uC0BbyjAC&pg=PA130&lpg=PA130&dq=computer+viruses+as+artificial+life&source=bl&ots=Uh-Oksfh6f&sig=f8yHoGRadVGtO8pucwuImn5PLPo&hl=en&sa=X&ved=0ahUKEwjxloe0q47LAhUCMyYKHVyyBhYQ6AEIJjAF