World on alert after pigs found infected with H1N1 virus

The Canadian Food Inspection Agency (CFIA) said Saturday that it was highly probable the estimated 200 pigs caught the virus from a Canadian who had been exhibiting flu-like symptoms after returning from Mexico.

The CFIA has put the swine herd under quarantine pending further testing needed to fully characterize the virus. It also noted that all of the pigs were recovering or had already recovered and that the chance those pigs could transfer the virus to a person is "remote".

Late Saturday, Mexican Health Minister Jose Angel Cordova raised the confirmed national death toll from Influenza A/H1N1 to 19 and the number of sick to 454, adding that the epidemic in the country is "in a stabilization phase".

"I believe we have enough elements to say that we are in a stabilization phase", Cordova said.

Also on Saturday, Mexican President Felipe Calderon discussed the epidemic with his U.S. counterpart Barack Obama in a telephone call.

The two leaders "spoke for 20 minutes this afternoon to share information about each country's efforts to limit the spread of the 2009 H1N1 flu strain and the importance of close U.S.-Mexican cooperation", the White House said in a statement.

Other confirmed infection cases worldwide include 197 in the U.S.; 85 in Canada; 15 in Spain; 15 in Britain; six in Germany; four in New Zealand; two each in Israel, France and South Korea; one each in Costa Rica, Ireland, Italy, Switzerland, Austria, China's Hong Kong, Denmark and the Netherlands.

In Mexico City, the government has ordered a prolonged five-day holiday to stem new infections.

The U.S. government has said schools with confirmed cases would close for at least 14 days because children can be contagious for seven to 10 days from when they get sick. More than 430 U.S. schools had closed.

Mike Ryan, WHO Director of Global Alert and Response, said the UN agency saw no evidence of sustained community spread outside North America, a condition that warrants declaring a full global pandemic.

On Wednesday, WHO raised its threat level to Phase 5 on a scale of six. Phase 5 means a virus has spread into at least two countries and is causing large outbreaks, while Phase 6 means outbreaks have been detected in two or more regions in the world and a pandemic is under way.

U.S. Centers for Disease Control and Prevention (CDC) said that about a third of the confirmed U.S. cases of swine flu are people who had been to Mexico and may have picked up the infection there.

Some health experts suggested that the H1N1 virus may have weakened as it was carried outside the country. 

Meanwhile, health authorities warned that it would be imprudent to take too much reassurance from signs the virus is weaker than feared.

The CDC said it's too early to declare victory. "We have seen times where things appear to be getting better and then get worse again", said Dr. Anne Schuchat, the U.S. agency's interim science and public health deputy director.