The World Health Organization is expressing concern about a possible swine flu pandemic as the number of confirmed cases rises in the United States and Mexico - and new cases have been reported in Canada. The Obama administration declared a public health emergency to mobilize federal and state resources to combat the infectious viral illness.
The World Health Organization has declared swine flu a "public health emergency of international concern". WHO Assistant Director-General Keiji Fukuda spoke with reporters via teleconference from Geneva.
"We have asked all countries to increase their surveillance and their watchfulness so we can detect as quickly as possible how this virus may or may not be spreading," said Keiji Fukuda.
Fukuda says the swine flu viruses detected in the United States and Mexico appear similar, despite the fact that symptoms reported in Mexico have been far more severe than in the United States. Mexico has recorded dozens of deaths from flu-like disease in recent days, although it is not clear whether swine flu was to blame in all cases.
Fakuda says this particular strain of swine flu could become more or less virulent over time.
"Influenza viruses are very prone to changing," he said. "They mutate easily. So when viruses evolve, they can become more dangerous for people - that is, to cause more serious disease. Or they are also able to mutate so they cause less serious disease."
Moments after he spoke, U.S. officials declared a public health emergency in response to at least 20 known cases in five states. Officials with the U.S. Centers for Disease Control say they expect to see more cases with possibly stronger symptoms in the future.
At a White House briefing, Homeland Security Secretary Janet Napolitano said the federal government is mobilizing to confront the health threat, including providing states access to millions of doses of stockpiled anti-viral treatments.
She appealed to the public for help.
"The government cannot solve this alone," said Janet Napolitano. "We need everybody in the United States to take some responsibility. If you are sick, stay home. Wash your hands. Take all of those reasonable measures that will help us militate and contain how many people actually get sick."
The WHO's Kieji Fukuda says, if there is good news, it is that the international community is far better equipped today than in previous years to combat infectious disease in a coordinated way.
"I believe the world is much, much better prepared than we have ever been for dealing with this kind of situation," said Fukuda. "In the past five years, countries have worked very hard to assess the threat of avian influenza. They have worked very hard on pandemic preparedness planning, and we have new tools. We have new surveillance. We have stockpiles of anti-viral drugs in case of a pandemic situation."
Those international preparations are being put to the test. Canada became the third country to confirm swine flu cases, with several people suffering mild cases of the illness in Nova Scotia and British Columbia. Other possible cases are under investigation in France and New Zealand.