Herpes Gladiatorium should actually be spelled Herpes Gladiatorum, which is the scientific name for Mat Herpes. The name Herpes Gladiatorum shows that it is a type of herpes most commonly occurring in athletes doing some sort of physical fighting, such as wrestlers, judo and jujitsu players, etc. This is what gladiatorum means. The athletes themselves usually call it "mat herpes" because all of these sports are performed on the mat.
But Herpes Gladiatorum only appears in sports involving constant and close skin contact. Boxers, for example, are usually not subject to this type of herpes because they a) do not have that much skin contact with each other; b) do not have skin contact with the ground.
The problem of the mat itself is also very important. Although herpes virus does not survive for long without a live host, you might contract Herpes Gladiatorum through the mat if it has been in use by others who already have the virus. Entire clubs or dojos have been known to be "infested" by mat herpes, eventually leading to complete desolation.
Therefore Herpes Gladiatorum is a disease to be treated seriously. If you notice the symptoms on yourself or anyone else in your club, seek help immediately.