Mexican authorities have closed schools and public buildings in the capital in a bid to contain a new flu virus suspected of killing¹ up to 60 people.

墨西哥当局下令关闭首都的学校和公共建筑以防止一种新型感冒病毒的传播，据悉该病毒可能已经导致60人致死。

Residents of the Mexican capital are taking precautionary measures

Public events were suspended（被暂时搁置的） and residents donned face masks as concern grew over the outbreak.

Health experts say tests so far seem to link it with a new swine flu（猪流感） virus that sickened eight in the southern US.

US experts said they were taking the virus seriously and working to learn as much as possible about it.

But both the US Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) said that there was no need at this point to issue travel advisories² for parts of Mexico or the US.

In Geneva, the WHO said an emergency committee would likely convene³（召集，聚集） over the weekend. It said it had prepared "rapid containment⁴ measures" in case they were needed.

In the US, the White House said it was monitoring events.

US links

Mexican authorities suspect the virus may have been involved in the deaths of about 60 people, mostly in and around Mexico City, since mid-March.

A new swine flu strain（紧张，血统） has been confirmed in 20 of the deaths and 40 others are being tested, Mexico's health secretary said. More than 900 other people are thought to have been infected.

Officials said most of those killed so far were young adults - rather than more vulnerable（易受伤害的，有弱点的） children and the elderly.

On Friday, Mexican President Felipe Calderon cancelled a trip and convened⁵ his cabinet to coordinate⁶ a response.

Masks were being handed out to residents and reports said the streets were far quieter than usual.

Dr Richard Besser, acting⁷ director of the CDC, said that preliminary tests on seven out of 14 samples from patients in Mexico had matched the virus found in the US.

Eight people have fallen sick - six in California and two in Texas - with a virus that experts say is a new strain of swine flu. All eight have recovered and only one was hospitalised.

Dr Besser said more information was needed to determine the extent of the threat posed by the virus.

"We are not at the point - WHO is not at the point - of declaring a pandemic（全国流行的）; we are at the point of trying to learn more about this virus, understand its transmission and how to control it," he said.

"In Mexico, other influenza⁸ viruses are circulating there, so sorting out which cases are caused by swine flu, which are other viruses and which are co-infections will be very important public health information."

Both the CDC and the WHO say they plan to send experts to Mexico to help investigate the virus.

Swine flu is a respiratory disease（呼吸道疾病） which infects pigs. It does not normally infect humans, although sporadic⁹ cases（散发病例） do occur usually in people who have had close contact with pigs.

There have also been rare documented cases of humans passing the infection to other humans.

Such cases are monitored very closely because of fears that a new strain of swine flu with the ability to pass from person to person could spark a pandemic.