猪流感再次引爆全球性流感?

 A journalist wears a mask during a soccer match at a stadium in Mexico City on April 26. REUTERS

WHILE reports of a unique form of flu – swine flu – were appearing around the world, there was the question: Is this the next big one? Is this the new virus that will kill millions, like the pandemics of 1918, 1957 and 1968?

Well, even the scientists' crystal ball may not help them come up with an answer that quickly. "It's hard to predict," said Anne Schuchat, PhD, of the United States Centers for Disease Control and Prevention. "We need to be prepared for change."

The center of the new virus is Mexico, where it has been blamed for 152 deaths and an estimated 2,000 cases, since April 13. Health officials around the world say they are investigating suspected cases in people who have been to Mexico. The level of concern rose even more when the US declared a public health emergencyon Sunday.

The flu makes people feel like they have a serious cold. In more serious cases, it may bring death. Flu viruses can be carried by humans, birds, and other animals and transmitted among themselves. It is believed that rotating flu viruses revisit humans in intervals and can leave a huge number of casualties.

Historically speaking, the sky has fallen three times in the last century: in 1918, 1957 and 1968. That was when "super" strains of the virus killed millions of people. That's far more damage than annual flu epidemics cause.

But history does not always teach lessons. During some of those periods, there were no modern genetic tools or surveillance systems to document viruses as they evolved. So scientists don't know how that evolution happened or how long it took. And, they can't tell us whether what we're seeing with swine flu is the lead up to a pandemic or a near miss.

Swine flu contains genetic elements from humans and birds as well as from pigs. It seems to spread among people more easily than past swine flus, which sometimes jumped from pigs to people.

Pigs are considered particularly susceptible to both bird and human viruses. They are a likely place for genetic mutationthat might lead to a new form of flu that spreads easily.

When "swine flu" appeared in the US in 1976, following global flu epidemics in 1957 and 1968, there was an idea that pandemics appeared every 10 years. But swine flu petered out, and there has been nothing else like it in the three decades since.

Leading scientists no longer accept the notion that flu pandemics come in regular intervals and that the world should have had a new one long before now.

Swine flu FAQs

Q: What are the symptoms?

A: They include fever, a cough, sore throat, aching body, chills, and fatigue. Some patients have also reported diarrhoea and vomiting.

Q: Is it safe to eat pork products?

A: The swine flu virus dies when the meat is heated to temperatures above 70 C.

Q: Is there a vaccine?

A: No. It will take months to make a new vaccine.

Q: Is China safe?

A: So far, no infection has been reported in China. It has also joined a worldwide flu surveillance.

BONUS

Vocabulary

outbreak

the sudden occurrence of a disease, usually limited

epidemic

wide-spread, rapid development of a disease among many individuals in a community

pandemic

an epidemic that occurs over an entire country or continent

Expression

public health emergency 公共卫生紧急事态

on alert 警惕状态

worldwide health alert 全球疫情预警

worldwide panic 全球性恐慌

global alert 全球警报