The rise was recorded by the Birmingham Research Unit of the Royal College of General Practitioners.
The unit's data show a jump in the average incidence rate of flu and similar from 40 to 69 per 100,000 in the penultimate week of 2008.
Unit director Douglas Fleming said rates of infection had increased in all regions and across all age groups.
"The recent increase is suggestive of an influenza outbreak greater than any seen in the last eight years," he said.
The news came a day after Health officials raised concerns that a rise in flu cases could put further strain on hospitals and A&E departments over Christmas.
An influx of illnesses related to the cold weather earlier this month has prompted experts to warn that hospitals are under "intense pressure".
They are concerned the situation will get worse this week when many doctors' surgeries will shut for four days.
