Scarlet fever increase reported, with Swansea worst hit
Cases of scarlet fever have risen by more than 100% in the first three months of 2014 compared to last year.
Public Health Wales (PHW) said it had received 139 reports between January and March - more than double the 65 reported this time last year.
Children aged two to seven are the worst affected, and the highest number of reported cases has been in Swansea.
The reason for the increase is not known, but PHW said it could be related to mild weather.
The disease causes a high temperature and a red rash, but can be treated with antibiotics.
The number of cases seen already this year is higher than the total number of cases reported in any year between 1995 and 2011, PHW said.
In 2012 there were 246 cases, and 186 in 2013, but health officials said it was too early to say whether this year would see higher figures.
PHW said the higher numbers could be related to the recent mild winter, but it had no firm evidence for that.
Dr Rhianwen Stiff, of PHW, advised parents to be vigilant of the symptoms.
"Scarlet fever is highly contagious. Although most cases of scarlet fever are mild and will clear up in a week or so, a course of antibiotics can speed your recovery and will lessen the chances of spreading the infection to other people," she said.
Anyone who suspects they or their child has scarlet fever should contact their GP or telephone NHS Direct for advice on 0845 46 47.