There is no evidence of the swine flu virus spreading in a sustained way outside North America, a top World Health Organization official says.

世界卫生组织一位官员说，没有迹象显示猪流感病毒会在北美洲以外的地区传播。

Michael Ryan, WHO: 'We have no evidence of sustained community spread outside North America'

Dr Michael Ryan, WHO Director of Global Alert and Response, praised European nations' handling of cases and said events did not seem out of control.

Mexico has cut its suspected death toll¹ by 75 to 101, indicating the outbreak may not be as bad as initially² feared.

The country has ordered a five-day shutdown in a bid to contain the virus.

Mexican Health Minister Jose Angel Cordova told the BBC that, based on samples tested, the mortality rate（死亡率） was comparable with that of seasonal³ flu.

Dr Ryan, meanwhile, said that there was "no evidence of sustained community spread outside of North America".

 spreading in an uncontrolled fashion," he said. "I think the next few days will tell as this develops."

"At the present time I would still propose that a pandemic is imminent⁴（逼近的，即将发生的） because we see the disease spread," Dr Ryan added.

The WHO is sending 2.4m courses of antiviral（抗病毒的） treatment to 72 nations around the world, Dr Ryan said, among them many developing countries.

But in cases of the virus outside Mexico, the effects do not appear to be severe.

Italy and the Irish Republic reported their first cases on Saturday, bringing the number of countries affected⁵ to 18.

Canada has announced that a herd⁶（兽群，人群） of pigs has tested positive for swine flu.

A senior agriculture official told a news conference that the pigs may have been infected by a farm worker who fell ill after returning from Mexico last month.

In Egypt, authorities have begun in earnest（郑重地） the slaughter⁷ of more than 300,000 pigs, in what was originally described as a precaution against（作为对的预防措施） swine flu.

Officials now say the move is a general health measure aimed at restoring order to Egypt's pig-rearing industry.

Experts say the virus cannot be caught from eating pork and there is no scientific rationale（基本原理） for the cull⁸（拣选，剔除）.

Five countries outside Mexico have confirmed person-to-person transmission.

China is trying to stop the spread of the virus, after getting its first case on Friday.

It says it will quarantine（隔离，封锁） all those who travelled on a flight from Mexico with a man suffering from swine flu.

Flights from Mexico have been suspended, and fellow guests and staff at the Hong Kong hotel where he was staying have been quarantined.

On Saturday, Mexico's foreign minister advised citizens not to travel to China to avoid the health measures being taken there against Mexicans.

International experts say there is no scientific rationale for Egypt's pig cull

Risk remains⁹

The US has now confirmed 160 cases of swine flu across 21 states but has seen only one death, of a Mexican toddler（初学走路的孩子） in Texas.

President Barack Obama said in his weekly radio address that the US was taking "all necessary precautions" to ensure it was prepared if the virus developed into "something worse".

Dr Anne Schuchat, acting¹⁰ deputy director of the US Centers for Disease Control and Prevention (CDC), said that although experts were concerned about the possibility of severe cases, the majority so far had been "mild, self-limited illness".

The new virus lacked the traits（特征，特点） that made the 1918 flu pandemic so deadly, another CDC official said.

Mr Cordova appeared to agree, saying that the Mexican authorities may, on reflection, have overestimated¹¹ the danger.

He said 43.7% of samples from suspected cases so far tested had come back positive, a total of 397. Sixteen in this group had died.

"That means that apparently¹², the rate of attack is not as wide as was thought," he said.

But he stressed that the risk of a rise in infection remains and said some elements of the five-day shutdown - in which many public buildings and businesses have been closed and people urged to stay at home - might be extended.