In mid 1994, the numbers vary from 4,500 to over 7,500 viruses. In 1996 the number climbed over 10,000. 1998 saw 20,000 and 2000 topped 50,000. It's easy to say there are more now. The confusion exists partly because it's difficult to agree on how to count viruses .
Most experts say yes.
Another problem comes from viruses that try to conceal themselves from scanners by mutating. In other words, every time the virus infects another file, it will try to use a different version of itself. These viruses are known as polymorphic viruses . At least one person counts this as 33 different viruses on their list. Many of the large number of viruses known to exist have not been detected in the wild but probably exist only in someone's virus collection.