GENEVA (Reuters) - Outbreaks of swine flu in humans in Mexico and the United States have the potential to cause a worldwide pandemic but it is too early to say whether they will, the World Health Organization said on Saturday.
WHO director-general Margaret Chan, after taking advice from experts who held emergency talks, declared the outbreaks to be a “public health emergency of international concern.” This means there is a risk of the new disease spreading to other countries.
In a statement, she urged health authorities worldwide to be on high alert for unusual patterns of disease and any rise in flu-like cases or severe pneumonia, and report them to the WHO.
“This is clearly an animal strain of the H1N1 virus and it has pandemic potential because it is infecting people,” Chan said earlier on a teleconference.
“However, we cannot say on the basis of currently available laboratory, epidemiological, and clinical evidence whether or not it will indeed cause a pandemic.”
The United Nations health agency has warned for several years that a new virus strain could spark a human influenza pandemic that could sweep around the globe and kill millions.
The new H1N1 flu strain -- a mixture of swine, human and avian flu viruses which has killed up to 68 people among 1,004 suspected cases in Mexico and infected eight in the United States -- is still poorly understood and the situation is evolving quickly, Chan said.
The emergency committee of experts that held three-hour talks with Chan and senior WHO officials on Saturday heard reports from the U.S. and Mexican authorities.
The experts “agreed that more information is needed” before a decision could be made concerning any change in the pandemic alert level, currently 3 on a scale of 1 (low risk of human cases) to 6 (efficient and sustained transmission between humans), a statement said.
“I would characterize the discussions as serious. The overall situation was reviewed by the committee and the importance of the discussions and situation was recognized,” Keiji Fukuda, acting WHO assistant director-general for health, security and the environment, told Reuters after the talks.
The emergency committee was composed of roughly 15 experts from all regions, including experts in epidemiology, laboratory testing, clinical treatment of cases, and travel, he said.
“The big push is to know what is the actual disease and virus situation we are dealing with now. It is too early to say whether things are changing for better or worse,” Fukuda said.
There were currently no indications of similar outbreaks elsewhere in the world, according to Chan, a former health director of Hong Kong.
Health officials worldwide should also be alert to large incidences of severe or fatal flu-like illness in groups other than young children and the elderly, the ages usually at highest risk from normal seasonal flu, she said.
Most of the dead in Mexico were aged between 25 and 45.
WHO experts in Mexico are helping authorities with disease surveillance, laboratory diagnosis and managing cases.
The WHO stood ready with antiviral drugs to combat the outbreaks in Mexico. But authorities have a sizeable supply of Tamiflu, known generically as oseltamivir, and made by Switzerland’s Roche Holding, which has proved effective against the new virus, according to the WHO.
“Influenza viruses are notoriously unpredictable and full of surprises, as we are seeing right now,” Chan said.
“We need to know how the virus is spread, what is the transmission pattern and whether or not it is going to cause severe disease and in what age group,” she said.
It was premature for the WHO to announce any travel advisories or to advise drugmakers to switch to producing a new vaccine -- to be derived from the new virus -- from their traditional production of seasonal influenza vaccines.
(For WHO information on swine flu go to:
Editing by Mark Trevelyan
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