A 25-year-old man found dead at a flat in Swansea is believed to have died from suspected measles following outbreak in the area.
Public Health Wales has said they are looking into the death of the man at flat in Port Tennant Road after police said he died a "sudden and unexplained" death.
South Wales Police confirm the death is not being treated as suspicious and are awaiting the results of a post-mortem. Next of kin have been informed.
Swansea coroner's office said they will not be able to confirm how the 25-year-old died untill next week but added they would not be "surprised" to see deaths in Wales die as a result of the epidemic.
If confirmed, the 25-year-old would be the first person to die in the measles outbreak in South Wales.
The measles epidemic is the biggest seen in the country in two decades, with more than 800 confirmed cases in Swansea and neighbouring Neath Port Talbot and Bridgend areas - 77 of whom have needed hospital treatment.
Dr Marion Lyons, director of health protection for Public Health Wales, said the organisation is aware of a "possible death from measles."
Lyons added: "My sympathies are with the family at such a tragic time.
"Whatever the cause of death in this case, we should not be surprised if, as the outbreak grows, we start to see deaths in Wales.
"Measles is a potentially fatal disease and around one in every 1,000 people who contracts measles in developed countries will die.
"Those not fully vaccinated with two doses of MMR are highly likely to catch measles, which is highly contagious. We know that there are unprotected people in all age groups but we have particular concerns about the 10 to 18 age group.
"We are therefore urging all parents of children who have missed doses of MMR to arrange vaccination for them as a matter of urgency.
"Symptoms of measles include fever, cold-like symptoms, fatigue, conjunctivitis and a distinctive red-brown rash that appears a few days into the illness. Anyone who thinks they or their child may have measles should speak to their GP immediately."
A major vaccination programme has gone under way in South Wales to help stop the outbreak spreading. More than 2,500 received the MMR vaccination jab needed in clinics over the weekend.