On 1 April 1999, a message circulated claiming that the Melissa virus had been modified to create a new virus, called 'Tuxissa'. The message claimed that this virus, once activated, would install Linux on the target computer.
The hoax virus gets its name from Linux's logo a penguin called 'Tux'.
There are many clues to the fact that this message is a hoax not least the fact that the original date on the 'alert' is 1 April, the reporter calls himself 'Humorix', and the claim that the 'virus' installs Linux 'invisibly in the background'.
No such virus currently exists. Although much technical information is presented in the email to give the hoax credibility, the actual details are clearly incorrect.