GENEVA - The World Health Organization still expects the swine flu pandemic to subside in the northern hemisphere over the summer, despite its persistence in the likes of the United States and Britain.

Sylvie Briand, interim head of the WHO's influenza program, said that cases of flu should still be expected but transmission would slow down thanks to the combined impact of the heat and school holidays.

"First of all there's a climactic aspect, knowing that flu viruses survive better in the cold than in the heat," Briand told AFP.

"The other important element is the density of contact between people. Children are on holiday and we don't have the outbreaks in schools like we had in the United States at the beginning of the epidemic," she added.

Even if the influenza A(H1N1) virus is new, "I think we will nonetheless have the same seasonal nature and transmission will decline in the northern hemisphere this summer, with a weak proportion of severe cases," Briand said.

England's Health Secretary Andy Burnham said Tuesday that 100,000 cases a day could occur across England, Northern Ireland, Scotland and Wales by the end of August if the current infection rate is maintained, stressing it was a projection.

In Washington, the White House said it would hold a high-level meeting next week bringing together top government officials to prepare for the possibility of a more severe outbreak of A(H1N1) influenza.

The meeting was called after the US Centers for Disease Control and Prevention (CDC) estimated that at least one million people in the United States have had swine flu, basing the projection partly on computer models.

British authorities have indicated that officially reported infections may fall well short of the true number of cases.

At the WHO Briand suggested this was largely expected.

"Of course, because there are already a lot of cases where people have few symptoms where they just have a light cough and don't go to the doctor," she said.

"There are even asymptomatic cases of people who are carrying the virus and do not even know it."

Some 89,921 people in 125 countries and territories have caught swine flu, with 382 having died since the outbreak was uncovered in April, World Health Organization data released Friday showed.

Some 12,720 new laboratory confirmed cases of influenza A(H1N1) cases have been reported, including 50 deaths, since the last bulletin on Wednesday.

Five more countries and territories -- Malta, Bosnia, Aruba, Palau and Uganda -- have reported cases.

The largest jump in caseloads was reported by the United States, with 6,185 new infections including 43 deaths, bringing its total to 33,902 including 170 deaths.

Mexico also reported an increase of 1,582 infections including three deaths, taking its total number infections to 10,262 including 119 deaths.

Some affected countries no longer keep track of all cases according to the UN health agency, while others do not report for each of the thrice-weekly bulletins.

The bulletin, however, reflects the spread of swine flu to new countries or territories.