The National Public Health Service for Wales (NPHS) said all four cases in Wrexham were confirmed as E.coli O157 phage type 2.

BBC: Four E.coli cases linked by tests

Last week, the NPHS said its research had shown the MMR uptake in one school in the Carmarthenshire area was as low as 14.8%.

BBC: Measles outbreak 'worst in years'

The nursery has been following the NPHS guidelines and remains open.

BBC: Measles outbreak 'worst in years'

The National Public Health Service (NPHS) said not all of these people would have swine flu and not everyone with flu-like symptoms would contact their GP.

BBC: More call handlers for swine flu

However, the NPHS said that this take-up level has yet to be reached, and in north Wales stands at just under 85% of children who are up-to-date with their measles jabs.

BBC: Jab reminder after measles cases

The NPHS said it was also working with North Wales NHS Trust to provide Ysgol Ffordd Dyffryn and Ysgol John Bright with vaccination sessions on Friday morning for pupils who have not had two doses of the MMR vaccine.

BBC: Jab reminder after measles cases