Severe swine flu cases "snowballing"

LONDON (Reuters) - The number of people needing hospital treatment for the H1N1 virus in England is "snowballing," although the rise in the overall number of estimated cases is slowing, health officials said on Thursday.

The Health Protection Agency (HPA) said there are now 848 patients in hospital with swine flu, of whom 172 are receiving critical care. In September, the number of swine flu patients in hospital was below 300.

Liam Donaldson, the chief medical officer, said the reason for the jump in severe cases was unknown, although the virus is not thought to have mutated.

"There has been a snowballing of cases in intensive care which is giving us concern," he told a news conference. "It is consistent with what happened in the southern hemisphere and it is unexplained."

There were an estimated 84,000 new cases of the flu in England, up from an estimated 78,000 the previous week, a rise of 7.7 percent, he added.

In the previous week, health officials said the number of estimated new cases had risen by nearly 50 percent.

The total number of people who have had flu since the outbreak began stands at 620,000. Donaldson said there was a small drop in the estimated number of people going to their GPs with flu-like symptoms, to 37.7 people per 100,000 compared to 42.8 in the previous week.

The HPA said the virus was generally mild and had shown no significant changes. The number of deaths of people with swine flu in England has reached 105, but not all those can be attributed to the virus.

(Reporting by Peter Griffiths; editing by Keith Weir)