By Alistair Bell
MEXICO CITY (Reuters) - Mexico said it was winning the battle against a deadly new strain of flu as it stayed largely shut for business and cases dropped, but global health officials hinted a pandemic was still likely.
World Health Organisation (WHO) chief Margaret Chan, paving the way for a rise in the agency's flu alert to the top of a six-point scale, warned against complacency over the good news from Mexico where the new H1N1 strain was first seen.
"Flu viruses are very unpredictable, very deceptive ... We should not be over-confident. One must not give H1N1 the opportunity to mix with other viruses," she said.
A hike to level 6 would declare a pandemic -- a disease spreading rapidly in more than one area -- but this would only reflect views on how the virus was spreading, not how bad its effects were. Chan said calm should prevail.
"Level 6 does not mean, in any way, that we are facing the end of the world. It is important to make this clear because (otherwise) when we announce level 6 it will cause an unnecessary panic," the director-general said.
Last week the U.N. agency raised its alert level twice, from 3 to 5 on a six-point scale, in response to the sustained transmission of H1N1 in Mexico and the United States.
Before issuing a level 6 alert, the WHO would need to see the virus spreading within communities in Europe or Asia.
The WHO said on Monday its laboratories had identified 985 H1N1 flu infections in 20 countries. Its toll lags national reports but is considered more scientifically secure.
Laboratory tests have shown 590 cases of the virus in Mexico, of which 25 people died -- the only deaths worldwide, bar a Mexican toddler visiting the United States.
MEXICO SET FOR NORMAL LIFE
In Mexico, offices and businesses stayed closed on Monday to try to prevent the spread of what has commonly been called swine flu, even though humans cannot catch it from pigs.
The health ministry announced on Sunday the epidemic had passed the worst and experts said the virus might be no more severe than normal flu.
"The virus has entered into a stabilisation phase. The cases are starting to decrease," President Felipe Calderon said on Sunday, adding that Mexico would begin to get back on its feet again this week after shutting restaurants, offices, cinemas and even churches for days.
"Our objective is to return to normality as soon as possible but what I want is to do that in secure conditions."
After days of alarm that had kept streets eerily quiet, Mexico City appeared more relaxed, with some people venturing out on bikes or running. Many no longer wore the surgical masks that have been almost obligatory in the city in the last week.
FLU SPREADS IN UNITED STATES
In the United States, the flu has spread to 30 states and infected 226 people, the U.S. Centres for Disease Control and Prevention said. It seems to hit mostly younger people, with very few cases among those over 50 years old.
CDC acting director Richard Besser said there were "encouraging signs" the new strain was not more severe than what would be seen during normal seasonal flu, but he still expected the new virus to have a significant impact on health.
"We're not out of the woods," he said.
The U.S. government said it hoped to have a vaccine ready for the new flu strain by the autumn.
The WHO said flu surveillance should be increased in humans and animals now that the latest H1N1 strain was found to have infected pigs in Canada.
Few countries are ready to take chances with the new virus.
Action by China to hold Mexicans in hotels and other places, ill or not, sparked a diplomatic dispute with Mexico, which said it was sending a plane to bring its citizens home.
A Mexican Embassy official in China said Chinese authorities were quarantining more than 70 Mexican business people and tourists after some showed flu symptoms.
China denied Mexican complaints that discrimination lay behind the measures.
In Turkey, a hospital denied a media report that one of its patients had been killed by the new strain.
(Additional reporting by Pascal Fletcher in Mexico City; Laura MacInnis in Geneva; Ben Harding in Madrid; Writing by Richard Meares)
