Rugby players and wrestlers may be at risk of a potentially serious skin disease called "scrumpox".
Scrumpox, a form the herpes virus, is spread by physical contact and research by scientists in Japan suggests a new strain of the virus could be even more pathogenic and is linked to contact sports such as rugby and wrestling.
According to the researchers from the National Institute of Infectious Diseases in Tokyo, Japan, a strain of herpes virus called BgKL has replaced the strain BgOL as one of the most common and pathogenic.
A study of the incidence of the disease amongst sumo wrestlers in Tokyo has found that in some cases the disease had recurred several times.
The researchers looked at samples taken from 39 wrestlers diagnosed with herpes gladiatorum, who were living in 8 different sumo stables in Tokyo between 1989 and 1994.
Scrumpox, or herpes gladiatorum, is a skin infection caused by the herpes virus, which can cause cold sores and is spread through direct skin-to-skin contact - it is common among rugby players and wrestlers.
Symptoms often start with a sore throat and swollen glands and the telltale blisters appear on the face, neck, arms or legs - as the disease is highly infectious, players who are infected are often withdrawn from competitions in order to stop the virus from spreading.
Dr. Kazuo Yanagi says the herpes virus can hide in nerve cells for long periods of time and symptoms can reappear later.
Dr Yanagi says their research showed that the BgKL strain of herpes is reactivated, spreads more efficiently and causes more severe symptoms than BgOL and other strains which suggests for the first time that the recurrence of herpes gladiatorum symptoms in humans may depend on the strain of virus.
Traditionally professional sumo wrestlers live and train together in a stable called a "heya" which provides the perfect environment for the virus to spread, but this facilitated the research into the spread of herpes virus.
The research into their living arrangements showed that the source of primary herpes infections among sumo wrestlers in each stable was their fellow wrestlers and two of the wrestlers in fact died as a result of their infections which was more severe than other virus types.
Dr. Yanagi says cases therefore need to be investigated so that future research on herpes may help identify herpes genes that are involved in recurrence and spread of the disease; Dr Yanagi hopes it will also lead to the development of medicines to stop the disease from spreading and recurring in infected patients.
Herpes is normally associated with the sexually-transmitted form, genital herpes, and cold sores, but in rare cases it can affect other parts of the body.
The research is published in the October issue of the Journal of General Virology.