ACCORDING to experts up to one million people in Wales could contact swine within the next 18 months.
The number of cases is expected to continue to rise, reaching epidemic levels in Wales at the end of September or beginning of October.
The NPHS influenza surveillance scheme's report from July 12 estimates there were 19.5 cases of a flu-like illness diagnosed by GPs out of every 100,000 people in Wales.
This is the equivalent of 585 people in Wales contacting their GPs in the last seven days with flu like symptoms - not all of these people will have swine flu.
So far there have been 64 laboratory confirmed cases in Wales.
There has been a total of 382 people hospitalised in the UK, seven of these in Wales, five of whom have been discharged.
It is hoped a vaccine will be available by the end of the summer, which could have some impact on the severity of the disease in Wales.
It is expected that priority groups will receive the vaccine first, given in two doses, three weeks apart.
Wales’ chief medical officer Dr Tony Jewell said six million doses of a swine flu vaccine will be delivered to Wales.
“If this appears to be a relatively mild illness then people do ask why we’re making such a fuss," said Dr Jewell.
“If one in three people in Wales are affected that’s one million people.
"Even though everyone will not be hospitalised or in critical care, there will be some that will.
“In terms of the impact on the economy and in the workplace, it is relatively high,” he added.
Shadow health minister Andrew Davies said: "I am very disappointed the National Flu Line which was meant to be set up at the end of last year, has still not materialised.
"It would have been the perfect vehicle to deal with the massive increase in calls currently being made to NHS Direct," he added.
If people develop flu like symptoms they should stay at home and check the various sources of information supplied - by leaflet, 24-hour telephone information lines or websites.
Anybody with severe symptoms needs to contact the GP or NHS Direct services.
If in a high risk group such as those with heart and lung disease, children under five-years-old or pregnant women, need to contact the GP services.
For further information visit the websites www.wales.gov.uk, www.nphs.wales.nhs.uk and www.hpa.org.uk Or call the Swine Flu Information Line on 08001513513 or NHS Direct Wales on 08454647.