U.K. authorities say a 25-year-old man is suspected to have died from measles as an epidemic continues to sweep across south Wales.

The outbreak has led to more than 800 infections and renewed discussions over the failure of some parents to vaccinate their children against the potentially fatal virus.

The most effective way of fighting it remains the measles mumps and rubella vaccine, often abbreviated MMR, but a vocal anti-vaccine movement has helped push measles cases to an 18-year high in England and Wales.

It's not yet clear whether the man died of the virus. in Wales said tests had shown he was infected with at the time of his death but that the cause was still being investigating.