A recent report highlighted a herpes virus strain that is making its way through rugby players and sumo wrestlers in Japan. They're calling it scrumpox (a combo of scrimmage and the pox-like appearance of the skin rash- also called herpes gladiatorum) and it is spread through skin-to-skin contact so that is why it is assumed to feature prominently in these 2 sports. This herpes type virus, similar to the HSV1 "cold sore" virus, can start with swollen lymph glands, a sore throat, telltale blisters on the face, arms and legs. It is highly contagious, so as soon as a diagnosis is made, the player is isolated, but that can be after he was incubating the virus and sharing it with other players.
BgOL was a strain of herpes virus already diagnosed in the world of sumo wrestlers, but it seems to have replaced by BgKL, a more common and pathogenic strain. It seems to happen when the BgOL virus is inactive but still present in the nerve cells. Two sumo wrestlers have died from complications from this herpes strain, so doctors and health experts are being vigilant.
If you play a contact sport or work out in gyms or participate on a team sport - be careful not to share towels and clothing items or robes, and always put a barrier between yourself and sitting surfaces if you are unclothed.