Mexican and US health experts searched on Saturday for signs an outbreak of a new flu strain is spreading further, after it killed up to 68 people in Mexico and infected eight in the United States. Mexico shut cinemas and museums and axed public events in the sprawling capital to try to prevent further infections.
Global health officials stopped short of declaring a pandemic but they warned more cases could come to light, making for a major outbreak. This strain of flu has spread between people and infected some individuals who had no contact with one another.
The World Health Organisation said the virus from 12 of the Mexican patients was the same genetically as a new strain of swine flu, designated H1N1, seen in eight people in California and Texas who later recovered. The Mexican government said the flu had killed 20 people and it may be responsible for 48 other deaths. In all, 1,004 suspected cases have been reported nation-wide.
-- New mixture of viruses in deadly flu
-- Person-to-person spread raises fear of major outbreak
-- Mexico soccer games in empty stadiums
Health Minister Jose Angel Cordova, speaking on the evening television news, encouraged people to avoid crowds and wear face masks, noting there was no guarantee that a vaccine would help against the new strain. The seasonal flu vaccine protects against one strain of the H1N1 virus, which is also circulating, but this new version is genetically different.
CDC experts are working on a vaccine against the new strain but it would take months to make. Cordova said the death rate appeared to have steadied and hospitals in the past few days had not seen the exponential rise in the number of people infected that many had feared.
Genetic analysis shows the flu strain is a never-before-seen mixture of swine, human and avian viruses. The fact that most of the dead were aged between 25 and 45 was seen as a worrying sign linked to pandemics, as seasonal flu tends to be more deadly among the elderly and the very young. "We realise the seriousness of this problem," Mexican President Felipe Calderon told health officials on Friday.
Two of Mexico's main soccer games, one of them in the capital's giant Aztec Stadium, will be played without spectators on Sunday to avoid large crowds. Finnish rock band The Rasmus cancelled a Mexico City concert. More cases could come to light as patients are tested in California, said Dr Gil Chavez, director of the Center for Infectious Diseases at the California Department of Public Health and the state's chief epidemiologist.
"The more we look the more we are likely to find," he said. In New York City, health officials were investigating what had sickened scores of students who fell ill with flu-like symptoms in a Queens high school on Thursday and Friday. The symptoms were reported as mild and a city health official said he could not speculate about whether flu was responsible. Little can be done to prevent an outbreak of flu from spreading, health experts warn, but common sense measures can help people protect themselves. Number one is hand-washing.
"Cover your cough or your sneeze, wash your hands frequently," advised Dr Richard Besser, acting director of the US Centers for Disease Control and Prevention. As far away as Hong Kong - the epicenter of the 2003 Sars epidemic and especially vigilant to any threat of infectious disease - the government's Centre for Health Protection said it was closely monitoring investigations in the United States and would analyse flu samples in the territory.