Summary

The name of the virus is derived from the following message found inside it.

NEWS FLASH!! Your system has been infected with the incurable decay of LEPROSY 1.00, a virus invented by PCM2 in June of 1990. Good luck!
Another variant is known, where the message has been changed to:

ATTENTION! Your computer has been afflicted with the incurable decay that is the fate wrought by Leprosy Strain B, a virus employing Cybernetic Mutation Technology(tm) and invented by PCM2 08/90.
Infected programs will either display this message or

Program too big to fit in memory
Leprosy is a 666 byte overwriting virus, and infected programs must be deleted, as there is no way to remove the virus. The only thing which is remarkable about it is the fact that the virus is written in C.

VARIANT:

Plague, Viper, Busted

Plague is a slightly shorter variant, 591 bytes long. It contains the following text:

Autopsy indicates the cause of death was THE PLAGUE Dedicated to the dudes at SHHS VIVE LE SHE-MAN!
Viper is related, but uses a slightly different encryption method and is 840 bytes long. Busted is yet another variant, which contains the text "Busted!"

VARIANT:

Xabaras

This variant has been changed quite a bit, probably in order to avoid detection by some anti-virus program. It is also longer - 1972 bytes.

VARIANT:

Leprosy-C, Leprosy-D, Scribble, Seneca, Surfer

Other variants, just as non-interesting as the previous ones.