Mexico said a new flu virus has killed up to 149 people and it ordered all schools to close across the country today as the disease spread in the United States, Canada and Europe, raising fears of a pandemic.
The World Health Organisation will raise its pandemic alert level to phase 4 over the deadly swine flu virus, indicating the infection can spread between humans to cause community-level outbreaks, a source familiar with the decision said today.
The decision came after experts held hours of emergency talks on whether to to raise the alert level from phase 3 due to the outbreak, which has killed up to 149 people in Mexico and spread to the United States, Canada and Europe.
Phase 4 is characterised by human-to-human spread of a new virus able to cause community-level outbreaks, according to the six-point scale the WHO revised earlier in the day. The level also indicates there is a significant increased risk of a pandemic but not that this is a foregone conclusion.
There were 40 confirmed cases of the flu in the United States, including 20 new cases at a New York City school where eight cases were already identified, US health officials said. Texas health authorities confirmed a third case of swine flu at a school near the Mexican border and California had eight confirmed cases.
US secretary of state Hillary Clinton urged caution in travelling to Mexico and the European Union also advised its citizens to avoid non-essential travel to areas affected by swine flu.
Mexico relies heavily on tourism, its third biggest source of foreign currency, and millions of Americans travel to Mexico every year.
The swine flu spreads quickly between humans and although it has so far killed people only in Mexico, governments across the world took measures to try to reduce its impact.
Although the flu is not caught from eating pig meat products several countries imposed import bans on pork from the United States. The virus is widely being called swine flu although it has components of classic avian, human and swine flu viruses and has not actually been seen in pigs.
Spain became the first country in Europe to confirm a case of swine flu when a man who returned from a trip to Mexico last week was found to have the virus.
But his condition, like that of 40 cases in the United States and six in Canada, was not serious. A New Zealand teacher and around a dozen students who recently returned from Mexico were also being treated as likely mild swine flu cases.
In the first confirmed cases in Britain, Scotland's health minister said two people tested positive for swine flu and were being treated under isolation in a hospital near Glasgow. Suspected cases were also reported in France, Italy and Israel. Four people are being tested in Ireland.
President Barack Obama said officials were closely monitoring cases of swine flu but he also tried to ease fears.
"This is obviously a cause for concern and requires a heightened state of alert. But it is not a cause for alarm," Obama told a meeting of the National Academy of Sciences.
Many countries have stepped up surveillance at airports and ports, using thermal cameras and sensors to identify people with fever, and the World Health Organisation has opened its 24-hour "war room" command centre.
The World Bank said last year that a global flu pandemic could cost $3 trillion and cut world GDP by 5 per cent.
In Mexico City, authorities have already shut schools, churches, stadiums, cinemas, theatres, bars and clubs, but most people went to work on Monday, buses and subway trains packed with commuters wearing surgical face masks.
Mexico was further unsettled by a 5.6-magnitude earthquake that rocked buildings in the capital on Monday, although there were no reports of deaths or damage.